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Introduction: The effects of salinity memory and its interaction with genetic diversity for drought tolerance and pollination system in terms of morphological, physiological, root characteristics and spectral reflectance indices (SRIs) in tall fescue is still unknown., Methods: Four tall fescue genotypes (two drought-sensitive and two drought-tolerant) were manually controlled to produce four selfed (S1) and four open-pollinated (OP) progeny genotypes (finally eight progeny genotypes). Then all genotypes were assessed for two years in greenhouse under five salinity treatments including control treatment (C), twice salinity stress treatment (primary mild salinity stress in two different stages and secondary at the end stage) (S1t1S2 and S1t2S2), once severe salinity stress treatment (secondary only, S2), and foliar spray of salicylic acid (SA) simultaneously with secondary salinity stress (H2S2)., Results: Results indicated that obligate selfing (S1) caused to inbreeding depression in RWC, plant growth, catalase activity, root length and the ratio of root/shoot (R/S). Once salinity stress treatment (S2) led to depression in most measured traits, while pre-exposure to salinity (salinity memory) (S1t1S2 and S1t2S2) improved photosynthetic pigments, proline, antioxidant enzymes and R/S., Conclusion: Salinity memory was more pronounced in drought-sensitive genotypes, while it was more evident in OP than S1 population. Foliar spray of salicylic acid (SA) was almost equally effective in reducing the effects of salinity stress in both populations. The efficacy of application was more pronounced in tolerant genotypes compared to sensitive ones. The possibility of modeling correlated spectral reflectance indices (SRIs) for prediction of different morphological, physiological and root characteristics will be discussed., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Safari, Majidi. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Belowground plant competition has been shown to induce varying responses, from increases to decreases in root biomass allocation or in directional root placement. Such inconsistencies could result from the fact that root allocation and directional growth were seldom studied together, even though they might represent different strategies. Moreover, variations in belowground responses might be due to different size hierarchies between plants, but this hypothesis has not been studied previously. In a greenhouse rhizobox experiment, we examined the way both root allocation and directional root placement of Pisum sativum are affected by the size and density of Festuca glauca neighbours, and by nutrient distribution. We found that root allocation of P. sativum increased with the density and size of F. glauca . By contrast, directional root placement was unaffected by neighbour size and increased either towards or away from neighbours when nutrients were patchily or uniformly distributed, respectively. These results demonstrate that directional root placement under competition is contingent on the distribution of soil resources. Interestingly, our results suggest that root allocation and directional placement might be uncoupled strategies that simultaneously provide stress tolerance and spatial responsiveness to neighbours, thus highlighting the importance of measuring both when studying belowground plant competition.

Background and Aims: In the subfamily Poöideae (Poaceae), certain grass species possess anti-herbivore alkaloids synthesized by fungal endophytes that belong to the genus Epichloë (Clavicipitaceae). The protective role of these symbiotic endophytes can vary, depending on alkaloid concentrations within specific plant-endophyte associations and plant parts., Methods: We conducted a literature review to identify articles containing alkaloid concentration data for various plant parts in six important pasture species, Lolium arundinaceum, Lolium perenne, Lolium pratense, Lolium multiflorum|Lolium rigidum and Festuca rubra, associated with their common endophytes. We considered the alkaloids lolines (1-aminopyrrolizidines), peramine (pyrrolopyrazines), ergovaline (ergot alkaloids) and lolitrem B (indole-diterpenes). While all these alkaloids have shown bioactivity against insect herbivores, ergovaline and lolitrem B are harmful for mammals., Key Results: Loline alkaloid levels were higher in the perennial grasses L. pratense and L. arundinaceum compared to the annual species L. multiflorum and L. rigidum, and higher in reproductive tissues than in vegetative structures. This is probably due to the greater biomass accumulation in perennial species that can result in higher endophyte mycelial biomass. Peramine concentrations were higher in L. perenne than in L. arundinaceum and not affected by plant part. This can be attributed to the high within-plant mobility of peramine. Ergovaline and lolitrem B, both hydrophobic compounds, were associated with plant parts where fungal mycelium is usually present, and their concentrations were higher in plant reproductive tissues. Only loline alkaloid data were sufficient for below-ground tissue analyses and concentrations were lower than in above-ground parts., Conclusions: Our study provides a comprehensive synthesis of fungal alkaloid variation across host grasses and plant parts, essential for understanding the endophyte-conferred defence extent. The patterns can be understood by considering endophyte growth within the plant and alkaloid mobility. Our study identifies research gaps, including the limited documentation of alkaloid presence in roots and the need to investigate the influence of different environmental conditions., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

High temperature is the most limiting factor in the growth of cool-season turfgrass. To cope with high-temperature stress, grass often adopt a memory response by remembering one past recurring stress and preparing a quicker and more robust reaction to the next stress exposure. However, little is known about how stress memory genes regulate the thermomemory response in cool-season turfgrass. Here, we characterized a transcriptional memory gene, Fa-heat shock protein 17.8 Class II (FaHSP17.8-CII) in a cool-season turfgrass species, tall fescue (Festuca arundinacea Schreb.). The thermomemory of FaHSP17.8-CII continued for more than 4 d and was associated with a high H3K4me3 level in tall fescue under heat stress (HS). Furthermore, heat acclimation or priming (ACC)-induced reactive oxygen species (ROS) accumulation and photosystem II (PSII) electron transport were memorable, and this memory response was controlled by FaHSP17.8-CII. In the fahsp17.8-CII mutant generated using CRISPR/Cas9, ACC+HS did not substantially block the ROS accumulation, the degeneration of chloroplast ultra-structure, and the inhibition of PSII activity compared with HS alone. However, overexpression of FaHSP17.8-CII in tall fescue reduced ROS accumulation and chloroplast ultra-structure damage, and improved chlorophyll content and PSII activity under ACC+HS compared with that HS alone. These findings unveil a FaHSP17.8-CII-PSII-ROS module regulating transcriptional memory to enhance thermotolerance in cool-season turfgrass., (© American Society of Plant Biologists 2021. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Cadmium is a common heavy metal pollutant. In some plants, its absorption is inhibited by exogenous phosphorus. Here, the effect of P supplementation on the growth of tall fescue exposed to Cd was evaluated in a hydroponic culture experiment. Plants were exposed to five concentrations of P (0, 0.25, 0.5, 0.75, and 1.0 mmol L -1 ) and three concentrations of Cd (50, 100, and 150 mg L -1 ), and plant growth, Cd content, absorption, physiological characteristics, and nutrient accumulation were investigated. P supplementation significantly reduced the Cd content, Cd translocation factor (TF), Cd removal efficiency, plant P absorption, chlorophyll content, glutathione levels, glutathione reductase levels, and superoxide dismutase (SOD) activity in tall fescue under Cd stress (P < 0.05). Moreover, it increased the vertical growth rate and biomass of tall fescue. At a constant P concentration, the biomass and vertical growth rate significantly decreased with an increasing Cd concentration, and the shoot Cd content, SOD activity, and TF significantly increased (P < 0.05). High P supplementation (0.75 and 1.0 mmol L -1 ) ameliorated the damage caused by 150 mg L -1 Cd stress, and the biomass, vertical shoot and vertical root growth rates were increased by 72.06-82.06%, 250.00-316.67%, 300.00-312.00%, respectively. In the plants subjected to 50 mg L -1 Cd stress, 0.5 mmol L -1 P supplementation enhanced biomass, vertical shoot and vertical root growth rates by 29.99%, 20.41%, and 21.43%, respectively, and reduced the Cd content in shoots (45.85%) and roots (9.71%). Except for the total potassium content and catalase activity, different concentrations of Cd negatively affected all parameters tested. Such negative effects were limited by P supplementation. Optimizing the nutrient composition and concentrations could minimize the potential negative impacts of Cd on plant growth., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Soil legacies play an important role for the creation of priority effects. However, we still poorly understand to what extent the metabolome found in the soil solution of a plant community is conditioned by its species composition and whether soil chemical legacies affect subsequent species during assembly. To test these hypotheses, we collected soil solutions from forb or grass communities and evaluated how the metabolome of these soil solutions affected the growth, biomass allocation and functional traits of a forb (Dianthus deltoides) and a grass species (Festuca rubra). Results showed that the metabolomes found in the soil solutions of forb and grass communities differed in composition and chemical diversity. While soil chemical legacies did not have any effect on F. rubra, root foraging by D. deltoides decreased when plants received the soil solution from a grass or a forb community. Structural equation modelling showed that reduced soil exploration by D. deltoides arose via either a root growth-dependent pathway (forb metabolome) or a root trait-dependent pathway (grass metabolome). Reduced root foraging was not connected to a decrease in total N uptake. Our findings reveal that soil chemical legacies can create belowground priority effects by affecting root foraging in later arriving plants., (© 2021 The Authors. Plant, Cell & Environment published by John Wiley & Sons Ltd.)

Water stress associated with drought-like conditions is a major factor limiting plant growth and impacts productivity of natural plant communities and agricultural crops. Molecular responses of plants to water stress have been studied most extensively in model species and crops, few of which have evolved natural drought tolerance. In the current study, we examined physiological and transcriptomic responses at multiple timepoints during increasing water stress and following initial recovery from stress in a drought-tolerant C 3 species, Festuca ovina . Results demonstrated non-linear transcriptomic changes during increasing stress, but largely linear declines in physiological measurements during this same period. Transcription factors represented approximately 12.7% of all differentially expressed genes. In total, 117 F. ovina homologs of previously identified and molecularly characterized drought-responsive plant genes were identified. This information will be valuable for further investigations of the molecular mechanisms involved in drought tolerance in C 3 plants.

Drought is a major agricultural and societal concern that causes farmers worldwide billions of dollars in annual losses. By revealing the as-of-yet unknown details of the biochemical and phytohormonal crosstalk occurring in drought-stressed plants, novel strategies can be pioneered to enhance drought tolerance in crop plants. Toward this goal, exogenous treatments containing the synthetic cytokinin 6-Benzylaminopurine (6-BA) were applied to the perennial monocot grass Festuca arundinacea (Tall Fescue). These plants were subjected to three irrigation levels: 100% ± 5%, 50% ± 5%, and 25% ± 5% of field capacity, at which a number of morpho-physiological and biochemical responses were evaluated. Furthermore, to elucidate the crosstalk between cytokinin (CK) and strigolactone (SL), we evaluated the activities of several SL-responsive genes. Drought conditions were shown to have widespread effects on morpho-physiological and biochemical indices. However, foliar application of 6-BA on tall fescue largely ameliorated drought stress symptoms. Water-soluble carbohydrates also declined significantly in response to CK over the course of drought progression, with virtually no change to starch content. Severe drought stress also upregulated a number of SL-response genes in the leaves of plants, indicating a correlation between the degree of drought severity and the quantity of SLs in tall fescue. Furthermore, the drought‒mediated induction of SL-signaling genes (including FaD14 and FaMax2) was inhibited in response to exogenous application of 6-BA, implying that 6-BA is a drought-dependent suppressor of SL-signaling genes. However, our results also hint at the existence of an as-of-yet poorly-characterized system of complex phytohormonal responses coordinated from multiple signaling pathways in response to drought., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Lolium multiflorum/Festuca arundinacea introgression forms have been proved several times to be good models to identify key components of grass metabolism involved in the mechanisms of tolerance to water deficit. Here, for the first time, a relationship between photosynthetic and antioxidant capacities with respect to drought tolerance of these forms was analyzed in detail. Two closely related L. multiflorum/F. arundinacea introgression forms distinct in their ability to re-grow after cessation of prolonged water deficit in the field were selected and subjected to short-term drought in pots to dissect precisely mechanisms of drought tolerance in this group of plants. The studies revealed that the form with higher drought tolerance was characterized by earlier and higher accumulation of abscisic acid, more stable cellular membranes, and more balanced reactive oxygen species metabolism associated with a higher capacity of the antioxidant system under drought conditions. On the other hand, both introgression forms revealed the same levels of stomatal conductance, CO 2 assimilation, and consequently, intrinsic water use efficiency under drought and recovery conditions. However, simultaneous higher adjustment of the Calvin cycle to water deficit and reduced CO 2 availability, with respect to the accumulation and activity of plastid fructose-1,6-bisphosphate aldolase, were clearly visible in the form with higher drought tolerance.

Background: As a cool-season grass species, tall fescue (Festuca arundinacea) is challenged by increasing temperatures. Heat acclimation or activation of leaf senescence, are two main strategies when tall fescue is exposed to heat stress (HS). However, lacking a genome sequence, the complexity of hexaploidy nature, and the short read of second-generation sequencing hinder a comprehensive understanding of the mechanism. This study aims to characterize the molecular mechanism of heat adaptation and heat-induced senescence at transcriptional and post-transcriptional levels., Results: Transcriptome of heat-treated (1 h and 72 h) and senescent leaves of tall fescue were generated by combining single-molecular real-time and Illumina sequencing. In total, 4076; 6917, and 11,918 differentially expressed genes (DEGs) were induced by short- and long-term heat stress (HS), and senescence, respectively. Venn and bioinformatics analyses of DEGs showed that short-term HS strongly activated heat shock proteins (Hsps) and heat shock factors (Hsfs), as well as specifically activated FK506-binding proteins (FKBPs), calcium signaling genes, glutathione S-transferase genes, photosynthesis-related genes, and phytohormone signaling genes. By contrast, long-term HS shared most of DEGs with senescence, including the up-regulated chlorophyll catabolic genes, phytohormone synthesis/degradation genes, stress-related genes, and NACs, and the down-regulated photosynthesis-related genes, FKBPs, and catalases. Subsequently, transient overexpression in tobacco showed that FaHsfA2a (up-regulated specifically by short-term HS) reduced cell membrane damages caused by HS, but FaNAC029 and FaNAM-B1 (up-regulated by long-term HS and senescence) increased the damages. Besides, alternative splicing was widely observed in HS and senescence responsive genes, including Hsps, Hsfs, and phytohormone signaling/synthesis genes., Conclusions: The short-term HS can stimulate gene responses and improve thermotolerance, but long-term HS is a damage and may accelerate leaf senescence. These results contribute to our understanding of the molecular mechanism underlying heat adaptation and heat-induced senescence.

Turfgrasses are monocotyledonous plants from the family Poaceae. They are widely used in green spaces and are considered one of the most economically important horticultural crops in the world. Turfgrass quality is affected by several environmental factors including light, which is involved in the quality decline of transplanted sod. Ultraviolet-B (UV-B) is an important regulator of plant growth and development. Plants growing and/or stored in protected systems, such as in sod production, may be more vulnerable to UV-B damage than those growing in the field due to acclimation. Few studies on the effects of UV-B on turfgrass physiology have been published. Therefore, the aim of this study was to evaluate the influence of UV-B irradiation on the photosynthetic performance of five cool-season turfgrasses, namely Agrostis stolonifera L., Festuca arundinacea Schreb., Poa supina Schrad., Poa pratensis L. and Lolium perenne L. Turfgrasses were exposed to 18.25 kJ m -2 d -1 biologically effective UV-B in growth chambers under controlled conditions. Measurements included photosynthetic pigments, chlorophyll fluorescence and gas exchanges monitored for 16 d-UV-B treatment and after recovery. Content of pigments decreased with UV-B exposure with significant differences among the species. UV-B also affected the photosystem II (PSII) efficiency depending on the exposure period and species. Similarly, gas exchange parameters showed different effects among species after UV-B exposure compromising the assimilation of CO 2 . Multivariate analysis highlighted three main clusters of species confirming their different UV-B tolerance and ability to restore PSII photochemistry after recovery, from which Festuca arundinacea resulted to be the most tolerant., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Masson SAS. All rights reserved.)

Many efforts have been made to select and isolate naturally occurring animal-friendly Epichloë strains for later reinfection into elite cultivars. Often this process involves large-scale screening of Epichloë -infected wild grass populations where strains are characterized and alkaloids measured. Here, we describe for the first time the use of genotyping-by-sequencing (GBS) on a collection of 217 Epichloë -infected grasses (7 S. arundinaceum , 4 L. perenne , and 206 S. pratensis ). This genotyping strategy is cheaper than complete genome sequencing, is suitable for a large number of individuals, and, when applied to endophyte-infected grasses, conveniently genotypes both organisms. In total, 6273 single nucleotide polymorphisms (SNPs) in the endophyte data set and 38 323 SNPs in the host data set were obtained. Our findings reveal a composite structure with three distinct endophyte clusters unrelated to the three main S. pratensis gene pools that have most likely spread from different glacial refugia in Eurasia. All three gene pools can establish symbiosis with E. uncinata . A comparison of the endophyte clusters with microsatellite-based fingerprinting of the same samples allows a quick test to discriminate between these clusters using two simple sequence repeats (SSRs). Concentrations of loline alkaloids and mycelial biomass are correlated and differ significantly among the plant and endophyte subpopulations; one endophyte strain has higher levels of lolines than others, and one specific host genotype is particularly suitable to host E. uncinata . These findings pave the way for targeted artificial inoculations of specific host-endophyte combinations to boost loline production in the symbiota and for genome association studies with the aim of isolating genes involved in the compatibility between meadow fescue and E. uncinata .

Impact of photosynthetic and antioxidant capacities on drought tolerance of two closely related forage grasses, Festuca arundinacea and Festuca glaucescens , was deciphered. Within each species, two genotypes distinct in drought tolerance were subjected to a short-term drought, followed by a subsequent re-watering. The studies were focused on: ( i ) analysis of plant physiological performance, including: water uptake, abscisic acid (ABA) content, membrane integrity, gas exchange, and relative water content in leaf tissue; ( ii ) analysis of plant photosynthetic capacity (chlorophyll fluorescence; gene expression, protein accumulation, and activity of selected enzymes of the Calvin cycle); and ( iii ) analysis of plant antioxidant capacity (reactive oxygen species (ROS) generation; gene expression, protein accumulation and activity of selected enzymes). Though, F. arundinacea and F. glaucescens revealed different strategies in water uptake, and partially also in ABA signaling, their physiological reactions to drought and further re-watering, were similar. On the other hand, performance of the Calvin cycle and antioxidant system differed between the analyzed species under drought and re-watering periods. A stable efficiency of the Calvin cycle in F. arundinacea was crucial to maintain a balanced network of ROS/redox signaling, and consequently drought tolerance. The antioxidant capacity influenced mostly tolerance to stress in F. glaucescens .

Festuca arundinacea is a model to work on the mechanisms of drought resistance in grasses. The crucial components of that resistance still remain not fully recognized. It was suggested that deep root system could be a crucial trait for drought avoidance strategy but the other components of root performance under water deficit have not paid much attention of scientists. In this study, two genotypes of F. arundinacea with a different ability to withstand soil water deficit were selected to perform comprehensive research, including analysis of root architecture, phytohormones, proteome, primary metabolome and lipidome under progressive stress conditions, followed by a rewatering period. The experiments were performed in tubes, thus enabling undisturbed development of root systems. We demonstrated that long roots are not sufficient to perfectly avoid drought damage in F. arundinacea and to withstand adverse environmental conditions without a disturbed cellular metabolism (with respect to leaf relative water potential and cellular membrane integrity). Furthermore, we proved that metabolic performance of roots is as crucial as its architecture under water deficit, to cope with drought stress via avoidance, tolerance and regeneration strategies. We believe that the presented studies could be a good reference for the other, more applied experiments, in closely related species., (� The Author(s) 2019. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

One major goal in plant evolutionary ecology is to address how and why tritrophic interactions mediated by phytochemical plant defences vary across species, space, and time. In this study, we tested three classical hypotheses about plant defences: (i) the resource-availability hypothesis, (ii) the altitudinal/elevational gradient hypothesis and (iii) the defence escalation hypothesis. For this purpose, predatory soil nematodes were challenged to hunt for root herbivores based on volatile cues from damaged or intact roots of 18 Alpine Festuca grass species adapted to distinct climatic niches spanning 2000 meters of elevation. We found that adaptation into harsh, nutrient-limited alpine environments coincided with the production of specific blends of volatiles, highly attractive for nematodes. We also found that recently-diverged taxa exposed to herbivores released higher amounts of volatiles than ancestrally-diverged species. Therefore, our model provides evidence that belowground indirect plant defences associated with tritrophic interactions have evolved under two classical hypotheses in plant ecology. While phylogenetic drivers of volatile emissions point to the defence-escalation hypothesis, plant local adaptation of indirect defences is in line with the resource availability hypothesis.

Abscisic acid (ABA) may play roles in mediating cross stress tolerance in plants. The objectives of this study were to investigate the priming effects of drought and ABA on heat tolerance and to determine how ABA may be involved in enhanced heat tolerance by drought. Focusing on the transcriptional level, two independent experiments were conducted, using a perennial grass species, tall fescue (Festuca arundinacea) and Arabidopsis. In experiment 1, tall fescue plants were exposed to mild drought by withholding irrigation for 8 days (drought priming) and foliar sprayed with ABA or an ABA-synthesis inhibitor (fluridone). After that they were subsequently subjected to heat stress (38/33°C day/night) for 25 days in growth chambers. In experiment 2, Arabidopsis Columbia ecotype (wild-type) and ABA-deficient mutant (aba3-1, CS157) were pre-treated with drought priming and then exposed to heat stress (45/40°C) for 3 days. The physiological analysis demonstrated that both drought priming and foliar application of ABA-enhanced heat tolerance in tall fescue, while drought priming had no significant effects on heat tolerance in ABA-deficient Arabidopsis plants. Application of fluridone to tall fescue and ABA-deficient mutants of Arabidopsis exhibited diminished or attenuated positive effects of drought priming on heat tolerance. ABA mediation of acquired heat tolerance by drought priming was associated with the upregulation of CDPK3, MPK3, DREB2A, AREB3, MYB2, MYC4, HsfA2, HSP18, and HSP70. Our study revealed the roles of ABA in drought priming-enhanced heat tolerance, which may involve transcriptional regulation for stress signaling, ABA responses and heat protection., (© 2019 Scandinavian Plant Physiology Society.)

Perennial plants and their associated microorganisms grow in the areas that may be contaminated with long-lived gamma-emitting radionuclides. This will induce gamma stress response in plants and their accompanying microorganisms. The present work investigated the growth and physiological responses of Epichloe endophyte infected tall fescue to gamma radiation, as well as whether the endophyte could persist and infect the host plant once exposed to gamma radiation. Seeds of Iranian native genotype of 75B + of tall fescue were exposed to different doses, including 5.0, 10.0, 15.0, 20.0, 30.0 and 40.0 krad of gamma ray from a 60 Co source. Irradiated and unirradiated seeds were sown in pots and grown under controlled conditions in the greenhouse. The growth and physiological parameters associated with plant tolerance to oxidative stress of host plants, as well as endophytic infection frequency (% of plants infected) and intensity (mean number of endophytic hyphae per the field of view), were examined in 3 months-old seedlings. The results indicated that all gamma radiation doses (except 5.0 kr) significantly reduced the height and survival percentage of the host plant. Days to the emergence of seedling increased gradually as gamma doses rose. A dose-rate dependent induction was seen for photosynthetic pigments and proline content. Malondialdehyde (MDA) content grew with elevation of irradiation doses. Depending on the dose and time, the activities of antioxidant enzymes in the host plant responded differently to gamma radiation. Gamma radiation altered the enzyme activities with sever decline in SOD and CAT activities. However, it had barely any effect on in APX and POD activities. The results also revealed that the persistence and intensity of endophyte were affected after gamma-ray irradiation. The initial percentage of tall fescue seeds infected with the endophyte was 91% in un-irradiated seeds. Presence of the viable endophyte started to decline significantly (23%) at 5.0 kr of gamma radiation. A dramatic reduction in the presence and intensity of endophyte occurred at 10.0 to 40.0 kr intensities. Gamma radiation × trait (GT)-biplot analysis indicated positive correlations between the endophyte symbiosis and antioxidant enzyme activities. Also, negative correlations were observed between the endophyte and MDA content in the host plant. Our results suggest that radiation stress (doses over 5.0 kr) caused reduction in the growth and antioxidant enzyme activities of the host plant that accompanied by a dramatic reduction in the persistence and intensity of endophyte fungi. Our findings have provided the basic information for future studies on the effect of gamma irradiation on the interaction between endophytic fungi and its host plant., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Adaptive responses are probably the most effective long-term responses of populations to climate change, but they require sufficient evolutionary potential upon which selection can act. This requires high genetic variance for the traits under selection and low antagonizing genetic covariances between the different traits. Evolutionary potential estimates are still scarce for long-lived, clonal plants, although these species are predicted to dominate the landscape with climate change. We studied the evolutionary potential of a perennial grass, Festuca rubra, in western Norway, in two controlled environments corresponding to extreme environments in natural populations: cold-dry and warm-wet, the latter being consistent with the climatic predictions for the country. We estimated genetic variances, covariances, selection gradients and response to selection for a wide range of growth, resource acquisition and physiological traits, and compared their estimates between the environments. We showed that the evolutionary potential of F. rubra is high in both environments, and genetic covariances define one main direction along which selection can act with relatively few constraints to selection. The observed response to selection at present is not sufficient to produce genotypes adapted to the predicted climate change under a simple, space for time substitution model. However, the current populations contain genotypes which are pre-adapted to the new climate, especially for growth and resource acquisition traits. Overall, these results suggest that the present populations of the long-lived clonal plant may have sufficient evolutionary potential to withstand long-term climate changes through adaptive responses., (© 2019 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2019 European Society For Evolutionary Biology.)

Aspergillus aculeatus has been shown to stimulate plant growth, but its role in plants abiotic stress tolerance and the underlying mechanisms are not fully documented. In this study, we investigated the mechanisms of A.aculeatus-mediated drought, heat and salt stress tolerance in tall fescue. The results showed that A.aculeatus inoculation improved drought and heat stress tolerance in tall fescue as observed from its effect on turf quality (TQ) and leaf relative water content (LWC). In the same stress conditions, A.aculeatus alleviated reactive oxygen species (ROS) induced burst and cell damage, as indicated by lower H 2 O 2 , electrolyte leakage (EL) and malondialdehyde (MDA) levels. Additionally, the A.aculeatus inoculated plants exhibited higher photosynthetic efficiency than uninoculated plants under drought, heat and salt stress conditions. The fungus reduced the uptake of Na + , and inoculated plants showed lower Na + /K + , Na + /Ca 2+ and Na + /Mg 2+ ratios compared to uninoculated ones under salt stress. Furthermore, comparative metabolomic analysis showed that A.aculeatus exclusively increased amino acid (such as proline and glycine) and sugar (such as glucose, fructose, sorbose, and talose) accumulation under drought and heat stress. However, there were no differences between inoculated and uninoculated plants except for changes in H 2 O 2 level, Na + in the root and photosynthetic efficiency under salt stress. Taken together, this study provides the first evidence of the protective roles of A.aculeatus in the tall fescue response to abiotic stresses, partially via protection of photosynthesis and modulation of metabolic homeostasis., (Copyright © 2019 Elsevier Masson SAS. All rights reserved.)

We performed a greenhouse experiment to assess how differences in AM fungal community composition affect competitive response of grassland plant species. We used a full factorial design to determine how inoculation with natural AM fungal communities from different habitats in Western Estonia affects the growth response of two grassland forbs (Leontodon hispidus L., Plantago lanceolata L.) to competition with a dominant grass (Festuca rubra L.). We used AM fungal inocula that were known to differ in AM fungal diversity and composition: more diverse AM fungal communities from open grasslands and less diverse AM fungal communities from former grassland densely overgrown by pines (young pine forest). The presence of AM fungi balanced competition between forb and grass species, by enhancing competitive response of the forbs. The magnitude of this effect was dependent on forb species identity and on the origin of the AM fungal inoculum in the soil. The grassland inoculum enhanced the competitive response of the forb species more effectively than the forest inoculum, but inoculum-specific competitive responses varied according to the habitat preference of the forb species. Our findings provide evidence that composition and diversity of natural AM fungal communities, as well as co-adaptation of plant hosts and AM-fungal communities to local habitat conditions, can determine plant-plant interactions and thus ultimately influence plant community structure in nature., Competing Interests: The authors have declared that no competing interests exist.

This study investigated effects of seed aging and imbibition on sugar metabolite concentrations in Epichloë endophyte-infected and endophyte-free seed of tall fescue ( Festuca arundinacea Schreb.). Two treatments, namely, accelerated aging and imbibition, were applied to the seeds, with embryo and endosperm tissues analyzed separately. Gas chromatography with flame ionization detection was employed for analysis of sugar metabolites within the seed tissues. Mannitol, ribitol, and trehalose were more abundant in embryo than endosperm tissues and were identified at consistently higher concentrations within endophyte-infected compared to endophyte-free seeds. The ratio of raffinose to sucrose significantly increased with seed aging in both endophyte-free and endophyte-infected embryo tissues, while significantly lower concentrations of trehalose were detected in tissues dissected from aged-seed regardless of endophyte status. This research provides fundamental insight into the metabolic details of endophyte survival in seed and provides a first evaluation of key carbohydrates present in the fungal-plant symbiosis.

Recent work on microbiomes is revealing the wealth and importance of plant-microbe interactions. Microbial symbionts are proposed to have profound effects on fitness of their host plants and vice versa, especially when their fitness is tightly linked. Here we studied local adaptation of host plants and possible fitness contribution of such symbiosis in the context of abiotic environmental factors. We conducted a four-way multi-year reciprocal transplant experiment with natural populations of the perennial grass Festuca rubra s.l. from northern and southern Finland, Faroe Islands and Spain. We included F. rubra with and without transmitted symbiotic fungus Epichloë that is vertically transmitted via host seed. We found local adaptation across the European range, as evidenced by higher host fitness of the local geographic origin compared with nonlocals at three of the four studied sites, suggesting that selection pressures are driving evolution in different directions. Abiotic factors did not result in strong fitness effects related to Epichloë symbiosis, indicating that other factors such as herbivory are more likely to contribute to fitness differences between plants naturally occurring with or without Epichloë. Nevertheless, in the case of asymmetric symbiosis that is obligatory for the symbiont, abiotic conditions that affect performance of the host, may also cause selective pressure for the symbiont., Competing Interests: The authors have declared that no competing interests exist.

Strigolactones (SLs) have recently been shown to play roles in modulating plant architecture and improving plant tolerance to multiple stresses, but the underlying mechanisms for SLs regulating leaf elongation and the influence by air temperature are still unknown. This study aimed to investigate the effects of SLs on leaf elongation in tall fescue ( Festuca arundinacea , cv. 'Kentucky-31') under different temperature regimes, and to determine the interactions of SLs and auxin in the regulation of leaf growth. Tall fescue plants were treated with GR24 (synthetic analog of SLs), naphthaleneacetic acid (NAA, synthetic analog), or N-1-naphthylphthalamic acid (NPA, auxin transport inhibitor) (individually and combined) under normal temperature (22/18 °C) and high-temperature conditions (35/30 °C) in controlled-environment growth chambers. Exogenous application of GR24 stimulated leaf elongation and mitigated the heat inhibition of leaf growth in tall fescue. GR24-induced leaf elongation was associated with an increase in cell numbers, upregulated expression of cell-cycle-related genes, and downregulated expression of auxin transport-related genes in elongating leaves. The results suggest that SLs enhance leaf elongation by stimulating cell division and interference with auxin transport in tall fescue., Competing Interests: The authors declare no conflict of interest.

Stress priming by exposing plants to a mild or moderate drought could enhance plant tolerance to subsequent heat stress. Lipids play vital roles in stress adaptation, but how lipidomic profiles change, affecting the cross-stress tolerance, is largely unknown. The objectives of this study were to perform lipidomics, to analyse the content, composition, and saturation levels of lipids in leaves of tall fescue (Festuca arundinacea) following drought priming and subsequent heat stress, and to identify major lipids and molecular species associated with priming-enhanced heat tolerance. Plants were initially exposed to drought for 8 days by withholding irrigation and subsequently subjected to 25 days of heat stress (38/33°C day/night) in growth chambers. Drought-primed plants maintained significantly higher leaf relative water content, chlorophyll content, photochemical efficiency, and lower electrolyte leakage than nonprimed plants under heat stress. Drought priming enhanced the accumulation of phospholipids and glycolipids involved in membrane stabilization and stress signalling (phosphatidic acid, phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, and digalactosyl diacylglycerol) during subsequent exposure to heat stress. The reprogramming of lipid metabolism for membrane stabilization and signalling in response to drought priming and subsequent exposure to heat stress could contribute to drought priming-enhanced heat tolerance in cool-season grass species., (© 2018 John Wiley & Sons Ltd.)

Grazing can induce changes in both plant productivity and nutritional quality, which may subsequently influence herbivore carrying capacity. While research on Soay sheep (Ovis aries L.) dynamics on Hirta Island in the St. Kilda archipelago has elucidated the complexity of population drivers, including parasites, the role of herbivore-generated feedbacks as an intrinsic regulating factor remains unclear. The sheep lack large predators and every 3-9 years undergo population crashes (overcompensatory mortality). We investigated the effects of grazing on (1) sward productivity and (2) quality (toxicity) of the primary forage species, red fescue (Festuca rubra L.), which is highly infected by an alkaloid-synthesizing fungal endophyte. Grazing had a negative impact on both forage quantity and quality. At higher sheep densities, impacts on sward growth were magnified, resulting in a nonlinear relationship with plant productivity. Simultaneously, endophyte hyphal load (and by inference, toxicity) peaked close to the time of a crash. A greenhouse experiment showed that alkaloid concentration in F. rubra increased in response to artificial defoliation. We conclude that at high sheep densities, grazing-mediated reductions in productivity, together with sustained alkaloid production, are likely to influence sheep dynamics. Future research should consider the interactive effects of forage toxicity, quantity, and nutritional content.

Vegetation is an important component of green roofs and may affect their hydrological performance through the processes of rainwater interception and evapotranspiration. Based on the rainfall-runoff observations of green roofs with four types of vegetation covers ( Portulaca grandiflora, Sedum lineare, Festuca elata , and bare substrate) located in Beijing during 26 rainfall events from April to October 2017, the impacts of vegetation cover on the hydrological performance of green roofs were investigated using runoff and peak discharge reduction rates and time-delay of runoff generation and peak discharge as indices. For the 12 green roofs, there was a significantly negative correlation ( P <0.01) between runoff reduction rate and rainfall event volume. For low rainfall (<10 mm), the runoff reduction rates of all the green roofs were equal or close to 100%. When the rainfall volume increased to about 30 mm, the runoff reduction rates dropped to below 70%. For the heaviest rainfall event during the observation period (81.4 mm), the runoff reduction rates of all the green roofs were less than 55%. The impacts of vegetation on the hydrological performance of green roofs changed with rainfall conditions. The differences between runoff reduction rates of green roofs with different types of vegetation cover were largest for the heavy rainfall events. For the moderate rainstorm events, the differences were slightly lower. For light rainfall events, however, no significant differences were observed among the runoff reduction rates of green roofs with different types of vegetation cover, as little runoff was generated. Vegetation cover could enhance the hydrological performance of green roofs, as the runoff and peak discharge reduction rates and time-delay of runoff generation and peak discharge of green roofs covered with vegetation were all better than those of the bare substrate for all the groups of rainfall events except the light rainfall. Vegetation-covered green roofs with P. grandiflora performed the best, as the average height and aboveground biomass per unit area of P. grandiflora were the largest.

Ergot alkaloids in endophyte-infected grasses inhibit prolactin secretion and reduce milk production in lactating cows. However, we previously showed that prepartum consumption of infected seed throughout the dry period did not inhibit subsequent milk production and prior exposure to bromocriptine (ergot peptide) actually increased production in the next lactation. To identify changes in the transcriptome and molecular pathways mediating the mammary gland's response to ergot alkaloids in the diet, RNA sequencing (RNA-seq) was performed on mammary tissues obtained from 22 multiparous Holstein cows exposed to 1 of 3 treatments. Starting at 90 ± 4 d prepartum, cows were fed endophyte-free fescue seed (control; CON), endophyte-free fescue seed plus 3×/wk subcutaneous injections of bromocriptine (BROMO; 0.1 mg/kg of BW), or endophyte-infected fescue seed (INF) as 10% of the diet. Cows were dried off 60 ± 2 d prepartum. Mammary biopsies from 4 (BROMO, INF) or 5 (CON) cows/treatment at each of the 3 phases were obtained: 7 d before dry off during the initial lactation (L1), mid-dry period (D), and 10 d postpartum (L2). Although tissue from the same cow was preferentially used at 3 phases (L1, D, L2), tissue from additional cows were used to as necessary to provide RNA of sufficient quality. Individual samples were used to generate individual RNA-seq libraries. Normalized reads of the RNA-seq data were organized into technical and biological replicates before processing with the RSEM software package. Each lactation phase was processed separately and genes that differed between any of 3 treatments were identified. A large proportion of genes differentially expressed in at least 1 treatment (n = 866) were found to be similarly expressed in BROMO and INF treatments, but differentially expressed from CON (n = 575, total for 3 phases). Of genes differentially expressed compared with CON, 104 genes were common to the L1 and L2 phases. Consistent with the production findings, networks most affected by treatments in L1 and L2 included lipid metabolism, small molecule biochemistry, and molecular transport, whereas networks related more to developmental and cellular functions and maintenance were evident during D phase. Similar patterns of expression in BROMO and INF during late and early lactation suggest involvement of similar cell signaling pathways or mechanisms of action for BROMO and INF and the importance of prolactin messaging pathways., (Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.)

Heat transcription factors ( Hsfs ) belong to a large gene family classified into A, B, and C groups, with classes A and B Hsfs being well-characterized and known for their roles in plant tolerance to abiotic stresses. The functions and roles of Class C Hsfs are not well-documented. The objectives of this study were to characterize a class C Hsf gene ( FaHsfC1b ) cloned from tall fescue ( Festuca arundinacea ), a perennial grass species, and to determine the physiological functions of FaHsfC1b in regulating heat tolerance by overexpressing FaHsfC1b in Arabidopsis thaliana . Full length cDNA of FaHsfC1b was cloned and the sequence alignment showed that it had high similarity to OsHsfC1b with typical DNA binding domain, hydrophobic oligomerization domain, and a nucleus localization signal. Transient expression with FaHsfC1b -eGFP in protoplasts of Arabidopsis leaves indicated its nucleus localization. qRT-PCR analysis showed that FaHsfC1b responded to heat, osmotic, salt, and cold stress in leaves and roots during 48-h treatment. Physiological analysis showed that FaHsfC1b overexpression enhanced plant survival rate, chlorophyll content, and photochemical efficiency, while it resulted in decreases in electrolyte leakage, H₂O₂ and O 2- content under heat stress. qRT-PCR showed that endogenous HsfC1 was induced in transgenic plants and the expression levels of heat protection protein genes, including several HSPs , AtGalSyn1 , AtRof1 , and AtHSA32 , as well as ABA-synthesizing gene ( NCED3 ) were significantly upregulated in transgenic plants overexpressing FaHsfC1b under heat stress. Our results first demonstrate that HsfC1b plays positive roles in plant tolerance to heat stress in association with the induction and upregulation of heat-protective genes. HsfC1b may be used as a candidate gene for genetic modification of cool-season plant species for improving heat tolerance.

Acclimation of photosynthetic apparatus to variable environmental conditions is an important component of tolerance to dehydration stresses, including salinity. The present study deals with the research on alterations in chloroplast proteome of the forage grasses. Based on chlorophyll fluorescence parameters, two genotypes of a model grass species-Festuca arundinacea with distinct levels of salinity tolerance: low salt tolerant (LST) and high salt tolerant (HST), were selected. Next, two-dimensional electrophoresis and mass spectrometry were applied under both control and salt stress conditions to identify proteins accumulated differentially between these two genotypes. The physiological analysis revealed that under NaCl treatment the studied plants differed in photosystem II activity, water content, and ion accumulation. The differentially accumulated proteins included ATPase B, ATP synthase, ribulose-1,5-bisphosphate carboxylase large and small subunits, cytochrome b6-f complex iron-sulfur subunit, oxygen-evolving enhancer proteins (OEE), OEE1 and OEE2, plastidic fructose-bisphosphate aldolase (pFBA), and lipocalin. A higher level of lipocalin, potentially involved in prevention of lipid peroxidation under stress, was also observed in the HST genotype. Our physiological and proteomic results performed for the first time on the species of forage grasses clearly showed that chloroplast metabolism adjustment could be a crucial factor in developing salinity tolerance.

Strigolactones (SL) have recently been found to play roles in regulating root development. However, it remains unclear how SL may mediate root elongation of perennial grass species under different temperatures that differentially affect root growth. The objectives of this study were to examine effects of SL on root elongation of tall fescue and to examine the interactive effects of SL and auxin in regulating root growth under both non-stress and heat stress conditions. Tall fescue (cv. 'Kentuck-31') plants were treated with GR24 (a synthetic strigolactones), NAA (α-naphthylacetic acid), or NPA (auxin transport inhibitor N-1-naphthylphalamic acid) or their combination under non-stress control and heat stress (35/30 °C) in growth chamber. Crown root elongation was evaluated by measuring root length. Cell number and length in root tips were measured under confocal microscope. Expression levels of genes related to cell growth, SL signaling and auxin transport were determined. SL promoted crown root elongation in tall fescue under normal temperature and heat stress, and alleviated heat-inhibition of root growth. GR24-enhanced root elongation was accompanied with the increase in cell numbers, up-regulation of cell cycle-related genes, and down-regulation auxin transport-related genes in crown root tips of tall fescue. The positive effects of SL for promoting crown root elongation in tall fescue under both non-stress and heat stress could be mainly due to its regulation of cell division and involve the interference of auxin transport., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Species response to climate change is influenced by predictable (selective) and unpredictable (random) evolutionary processes. To understand how climate change will affect present-day species, it is necessary to assess their adaptive potential and distinguish it from the effects of random processes. This will allow predicting how different genotypes will respond to forecasted environmental change. Space for time substitution experiments are an elegant way to test the response of present day populations to climate variation in real time. Here we assess neutral and putatively adaptive variation in 11 populations of Festuca rubra situated along crossed gradients of temperature and moisture using molecular markers and phenotypic measurements, respectively. By comparing population differentiation in putatively neutral molecular markers and phenotypic traits (QST-FST comparisons), we show the existence of adaptive differentiation in phenotypic traits and their plasticity across the climatic gradient. The observed patterns of differentiation are due to the high genotypic and phenotypic differentiation of the populations from the coldest (and wettest) environment. Finally, we observe statistically significant covariation between markers and phenotypic traits, which is likely caused by isolation by adaptation. These results contribute to a better understanding of the current adaptation and evolutionary potential to face climate change of a widespread species. They can also be extrapolated to understand how the studied populations will adjust to upcoming climate change without going through the lengthy process of phenotyping.

Main Conclusion: Evergreen plants are more vulnerable than grasses and birch to snow and temperature variability in the sub-Arctic. Most Arctic climate impact studies focus on single factors, such as summer warming, while ecosystems are exposed to changes in all seasons. Through a combination of field and laboratory manipulations, we compared physiological and growth responses of dominant sub-Arctic plant types to midwinter warming events (6 °C for 7 days) in combination with freezing, simulated snow thaw and nitrogen additions. We aimed to identify if different plant types showed consistent physiological, cellular, growth and mortality responses to these abiotic stressors. Evergreen dwarf shrubs and tree seedlings showed higher mortality (40-100%) following extreme winter warming events than Betula pubescens tree seedlings and grasses (0-27%). All species had growth reductions following exposure to - 20 °C, but not all species suffered from - 10 °C irrespective of other treatments. Winter warming followed by - 20 °C resulted in the greatest mortality and was strongest among evergreen plants. Snow removal reduced the biomass for most species and this was exacerbated by subsequent freezing. Nitrogen increased the growth of B. pubescens and grasses, but not the evergreens, and interaction effects with the warming, freezing and snow treatments were minor and few. Physiological activity during the winter warming and freezing treatments was inconsistent with growth and mortality rates across the plants types. However, changes in the membrane fatty acids were associated with reduced mortality of grasses. Sub-Arctic plant communities may become dominated by grasses and deciduous plants if winter snowpack diminishes and plants are exposed to greater temperature variability in the near future.

Turfgrass are widely cultivated ornamental plants that have important ecological, societal and economical values. However, many turfgrass species are susceptible to drought and demand frequent irrigation thus consuming large amounts of water. With the ultimate goal of improving drought resistance in turfgrass, we identified several ABA receptors in turfgrass that are important to mediate ABA signaling and drought stress response. The ABA receptor FePYR1 from turfgrass Festuca elata was demonstrated to bind ABA as a monomer. Crystal structure analysis revealed that FePYR1 recognizes and binds ABA by the common gate-latch-lock mechanism resembling the Arabidopsis ABA receptors, but the ABA binding pocket in FePYR1 shows discrepant residues resulting in different binding affinity to ABA. Structure-guided alterations of amino acid residues in FePYR1 generated ABA receptor variants with significantly increased ABA binding affinity. Expression of FePYR1 in Arabidopsis conferred enhanced drought resistance in the transgenic plants. These findings provided detailed information about FePYR1 and demonstrated that structure-assisted engineering could create superior ABA receptors for improving plant drought resistance. The detailed structural information of FePYR1 would also assist future rational design of small molecules targeting specific ABA receptors in economically important plant species.

Herbicide drift may have unintended impacts on native vegetation, adversely affecting individual species and plant communities. To determine the potential ecological effects of herbicide drift, small plant community plots were constructed using 9 perennial species found in different Willamette Valley (OR, USA) grassland habitats. Studies were conducted at 2 Oregon State University (Corvallis, OR, USA) farms in 2 separate years, with single and combined treatments of 0.01 to 0.2× field application rates (f.a.r.) of 1119 g ha -1 for glyphosate (active ingredient [a.i.] of 830 g ha -1 acid glyphosate) and 560 g ha -1 a.i. for dicamba. Plant responses were percentage of cover, number of reproductive structures, mature and immature seed production, and vegetative biomass. Herbicide effects differed with species, year, and, to a lesser extent, farm. Generally, 0.1 to 0.2× f.a.r. of the herbicides were required to affect reproduction in Camassia leichtlinii, Elymus glaucus, Eriophyllum lanatum, Festuca idahoensis, Iris tenax, and Prunella vulgaris. Eriophyllum lanatum also had a significant increase in percentage of immature seed dry weight with 0.01× f.a.r. of dicamba or the combination of glyphosate plus dicamba. Other species showed similar trends, but fewer significant responses. These studies indicated potential effects of low levels of herbicides on reproduction of native plants, and demonstrated a protocol whereby species growing in a constructed plant community can be evaluated for ecological responses. Environ Toxicol Chem 2017;36:2799-2813. Published 2017 SETAC. This article is a US government work and, as such, is in the public domain in the United States of America., (Published 2017 SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.)

Abscisic acid (ABA) is known to play roles in regulating plant tolerance to various abiotic stresses, but whether ABA's effects on heat tolerance are associated with its regulation of heat stress transcription factors (HSFs) and heat shock proteins (HSPs) is not well documented. The objective of this study was to determine whether improved heat tolerance of tall fescue ( Festuca arundinacea Schreb.) by ABA was through the regulation of HSFs and HSPs. ABA-responsive transcriptional factors, ABA-responsive element binding protein 3 (FaAREB3) and dehydration-responsive element binding protein 2A (FaDREB2A) of tall fescue, were able to bind to the cis -elements in the promoter of tall fescue heat stress transcription factor A2c (Fa HSFA2c ). Exogenous ABA (5 μM) application enhanced heat tolerance of tall fescue, as manifested by increased leaf photochemical efficiency and membrane stability under heat stress (37/32 °C, day/night). The expression levels of FaHSFA2c , several tall fescue HSPs ( FaHSPs ), and ABA-responsive transcriptional factors were up-regulated in plants treated with ABA. Deficiency of Arabidopsis heat stress transcription factor A2 ( AtHSFA2 ) suppressed ABA-induction of AtHSPs expression and ABA-improved heat tolerance in Arabidopsis. These results suggested that HSFA2 plays an important role in ABA-mediated plant heat tolerance, and FaAREB3 and FaDREB2A may function as upstream trans -acting factors and regulate transcriptional activity of FaHSFA2c and the downstream FaHSPs , leading to improved heat tolerance., Competing Interests: The authors declare no conflict of interest.

Roughstalk bluegrass (Poa trivialis) is a weed in cool season grass seed production fields in Oregon. Populations of this weed are often greater in fields prone to waterlogging. A greenhouse study was conducted to investigate the morphological and physiological differences between recently established roughstalk bluegrass and tall fescue (Lolium arundinaceum) plants in response to simulated waterlogging. Differences in root morphological development and root respiration were found between waterlogged tall fescue and roughstalk bluegrass. Plants after 4 weeks of waterlogging, leaf number, plant height, and root biomass were reduced more in tall fescue than in roughstalk bluegrass plants. The root length increased 6% in waterlogged tall fescue plants, and decreased 42% in waterlogged roughstalk bluegrass plants, which lead to a shallower root system in roughstalk bluegrass. Root aerenchyma area increased more in waterlogged roughstalk bluegrass than in tall fescue. Alcohol dehydrogenase and lactate dehydrogenase activities increased in the roots of both species, but not in the leaves. The increases were greater in tall fescue than in roughstalk bluegrass. Turf quality, aboveground biomass, photosynthetic capacity, and water-soluble carbohydrate concentrations were reduced by waterlogging, but there were no differences over time or species. Thus, the shallower root system, larger aerenchyma, and reduced fermentation rates were the characteristics most likely to contribute to better waterlogging tolerance in roughstalk bluegrass compared to tall fescue and invasion of roughstalk bluegrass in waterlogged cool season grass seed fields.

Climate change impacts rainfall patterns which may lead to drought stress in rain-fed agricultural systems. Crops with higher drought tolerance are required on marginal land with low precipitation or on soils with low water retention used for biomass production. It is essential to obtain plant breeding tools, which can identify genotypes with improved drought tolerance and water use efficiency (WUE). In C 3 plant species, the variation in discrimination against 13 C (Δ 13 C) during photosynthesis has been shown to be a potential indicator for WUE, where discrimination against 13 C and WUE were negatively correlated. The aim of this study was to determine the variation in the discrimination against 13 C between species and cultivars of three perennial C 3 grasses (Dactylis glomerata (cocksfoot), Festuca arundinacea (tall fescue) and Phalaris arundinacea (reed canary grass)) and test the relationships between discrimination against 13 C, season-long water use WUE B , shoot and root biomass production in plants grown under well-watered and water-limited conditions. The grasses were grown in the greenhouse and exposed to two irrigation regimes, which corresponded to 25% and 60% water holding capacity, respectively. We found negative relationships between discrimination against 13 C and WUE B and between discrimination against 13 C and shoot biomass production, under both the well-watered and water-limited growth conditions (p < 0.001). Discrimination against 13 C decreased in response to water limitation (p < 0.001). We found interspecific differences in the discrimination against 13 C, WUE B , and shoot biomass production, where the cocksfoot cultivars showed lowest and the reed canary grass cultivars highest values of discrimination against 13 C. Cocksfoot cultivars also showed highest WUE B , shoot biomass production and potential tolerance to water limitation. We conclude that discrimination against 13 C appears to be a useful indicator, when selecting C 3 grass crops for biomass production under drought conditions., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Background: Lead (Pb) is one of the most toxic heavy metal environmental pollutants. Tall fescue is an important cold season turf grass which can tolerate and accumulate substantial amount of Pb. To estimate genes related to Pb response and the molecular mechanism associated with Pb tolerance and accumulation, we analyzed the transcriptome of tall fescue in response to Pb treatment., Results: RNA-sequencing was performed in two tall fescue cultivars, Pb tolerant Silverado and Pb sensitive AST7001. A total of 810,146 assembled unique transcripts representing 25,415 unigenes were obtained from the tall fescue leaves. Among the panel, 3,696 differentially expressed genes (DEGs) were detected between the Pb treated (1000 mg/L) and untreated samples. Gene ontology (GO) and pathway enrichment analysis demonstrated that the DEGs were mainly implicated in energy metabolism, metabolism of terpenoids and polyketides, and carbohydrate metabolism related pathways. The expression patterns of 16 randomly selected genes were in consistent with that from the Solexa analysis using quantitative reverse-transcription PCR. In addition, compared to the common transcriptional response to Pb stress in both cultivars, the regulation of numerous genes including those involved in zeatin biosynthesis, limonene and pinene degradation, phagosome was exclusive to one cultivar., Conclusions: The tall fescue assembled transcriptome provided substantial molecular resources for further genomics analysis of turfgrass in response to heavy metal stress. The significant expression difference of specific unigenes may account for Pb tolerance or accumulation in two different tall fescue cultivars. This study provided new insights for the investigation of the molecular basis of Pb tolerance and accumulation in tall fescue as well as other related turf grass species.

Heat stress transcription factors (HSFs) compose a large gene family, and different members play differential roles in regulating plant responses to abiotic stress. The objectives of this study were to identify and characterize an A2-type HSF, FaHsfA2c, in a cool-season perennial grass tall fescue (Festuca arundinacea Schreb.) for its association with heat tolerance and to determine the underlying physiological functions and regulatory mechanisms of FaHsfA2c imparting plant tolerance to heat stress. FaHsfA2c was localized in nucleus and exhibited a rapid transcriptional increase in leaves and roots during early phase of heat stress. Ectopic expression of FaHsfA2c improved basal and acquired thermotolerance in wild-type Arabidopsis and also restored heat-sensitive deficiency of hsfa2 mutant. Overexpression of FaHsfA2c in tall fescue enhanced plant tolerance to heat by triggering transcriptional regulation of heat-protective gene expression, improving photosynthetic capacity and maintaining plant growth under heat stress. Our results indicated that FaHsfA2c acted as a positive regulator conferring thermotolerance improvement in Arabidopsis and tall fescue, and it could be potentially used as a candidate gene for genetic modification and molecular breeding to develop heat-tolerant cool-season grass species., (© 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.)

According to predicted changes in climate, waterlogging events may occur more frequently in the future during autumn and winter at high latitudes of the Northern Hemisphere. If excess soil water coincides with the process of cold acclimation for plants, winter survival may potentially be affected. The effects of waterlogging during cold acclimation on stomatal aperture, relative water content, photochemical activity of photosystem II, freezing tolerance and plant regrowth after freezing were compared for two prehardened overwintering forage grasses, Lolium perenne and Festuca pratensis. The experiment was performed to test the hypothesis that changes in photochemical activity initiated by waterlogging-triggered modifications in the stomatal aperture contribute to changes in freezing tolerance. Principal component analysis showed that waterlogging activated different adaptive strategies in the two species studied. The increased freezing tolerance of F. pratensis was associated with increased photochemical activity connected with stomatal opening, whereas freezing tolerance of L. perenne was associated with a decrease in stomatal aperture. In conclusion, waterlogging-triggered stomatal behavior contributed to the efficiency of the cold acclimation process in L. perenne and F. pratensis., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

In germinating seeds under unfavorable environmental conditions, the mobilization of stores in the cotyledons is delayed, which may result in a different modulation of carbohydrates balance and a decrease in seedling vigor. Tall fescue (Festuca arundinacea Schreb.) caryopses grown at 4°C in the dark for an extended period in complete absence of nutrients, showed an unexpected ability to survive. Seedlings grown at 4°C for 210 days were morphologically identical to seedlings grown at 23°C for 21 days. After 400 days, seedlings grown at 4°C were able to differentiate plastids to chloroplast in just few days once transferred to the light and 23°C. Tall fescue exposed to prolonged period at 4°C showed marked anatomical changes: cell wall thickening, undifferentiated plastids, more root hairs and less xylem lignification. Physiological modifications were also observed, in particular related to sugar content, GA and ABA levels and amylolytic enzymes pattern. The phytohormones profiles exhibited at 4 and 23°C were comparable when normalized to the respective physiological states. Both the onset and the completion of germination were linked to GA and ABA levels, as well as to the ratio between these two hormones. All plants showed a sharp decline in carbohydrate content, with a consequent onset of gradual sugar starvation. This explained the slowed then full arrest in growth under both treatment regimes. The analysis of amylolytic activity showed that Ca2+ played a central role in the stabilization of several isoforms. Overall, convergence of starvation and hormone signals meet in crosstalk to regulate germination, growth and development in tall fescue., Competing Interests: The authors have declared that no competing interests exist.

The aim of this study was to investigate the role of endogenous nitric oxide in protective effects of He-Ne laser on salt stressed-tall fescue leaves. Salt stress resulted in significant increases of membrane injury, reactive oxygen species (ROS) production, polyamine accumulation, and activities of SOD, POD, and APX, while pronounced decreases of antioxidant contents, CAT activity and intracellular Ca(2+) concentration in seedlings leaves. He-Ne laser illumination caused a distinct alleviation of cellular injury that was reflected by the lower MDA amounts, polyamine accumulation and ROS levels at the stress period. In contrast, the laser treatment displayed a higher Ca(2+) concentration, antioxidant amounts, NO release, antioxidant enzyme, and NOS activities. These responses could be blocked due to the inhibition of NO biosynthesis by PTIO (NO scavenger) or LNNA (NOS inhibitor). The presented results demonstrated that endogenous NO might be involved in the progress of He-Ne laser-induced plant antioxidant system activation and ROS degradation in order to enhance adaptive responses of tall fescue to prolonged saline conditions.

Background and Aims: Rhizomes are underground stems with meristematic tissues capable of generating shoots and roots. However, mechanisms controlling rhizome formation and growth are yet to be completely understood. The objectives of this study were to investigate whether rhizome development could be regulated by cytokinins (CKs) and gibberellic acids (GAs), and determine underlying mechanisms of regulation of rhizome formation and growth of tall fescue (Festuca arundinacea) by a CK or GA through proteomic and transcript analysis., Methods: A rhizomatous genotype of tall fescue ('BR') plants were treated with 6-benzylaminopurine (BAP, a synthetic cytokinin) or GA3 in hydroponic culture in growth chambers. Furthermore, comparative proteomic analysis of two-dimensional electrophoresis and mass spectrometry were performed to investigate proteins and associated metabolic pathways imparting increased rhizome number by BAP and rhizome elongation by GA3 KEY RESULTS: BAP stimulated rhizome formation while GA3 promoted rhizome elongation. Proteomic analysis identified 76 differentially expressed proteins (DEPs) due to BAP treatment and 37 DEPs due to GA3 treatment. Cytokinin-related genes and cell division-related genes were upregulated in the rhizome node by BAP and gibberellin-related and cell growth-related genes in the rhizome by GA3 CONCLUSIONS: Most of the BAP- or GA-responsive DEPs were involved in respiratory metabolism and amino acid metabolism. Transcription analysis demonstrated that genes involved in hormone metabolism, signalling pathways, cell division and cell-wall loosening were upregulated by BAP or GA3 The CK and GA promoted rhizome formation and growth, respectively, by activating metabolic pathways that supply energy and amino acids to support cell division and expansion during rhizome initiation and elongation in tall fescue., (© The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Human assisted plant invasions from Europe to North America have been more common than the reverse. We tested endophyte-mediated performance of tall fescue in parallel three year experiments in Europe and the USA using endophyte infected and uninfected wild and cultivated plants. Experimental plants were subjected to nutrient and water treatments. Whereas endophyte infection increased tall fescue performance in general, the effects of endophytes on plant growth and reproduction varied among plant origins under different environmental conditions. Naturally endophyte-free Finnish cultivar 'Retu' performed equally well as 'Kentucky-31' in both geographic locations. All Eurasian origin plants performed well in the US. In Finland, plants established well and both cultivars survived over the first winter. However, winter mortality of 'Kentucky-31' plants was higher, particularly in fertilized soils in the subsequent winters. Our results suggest that tall fescue ecotype 'Kentucky-31' that flourishes in North America is poorly adapted to Northern European conditions.

Two main mechanisms are thought to affect the prevalence of endophyte-grass symbiosis in host populations: the mode of endophyte transmission, and the fitness differential between symbiotic and non-symbiotic plants. These mechanisms have mostly been studied in synthetic grass populations. If we are to improve our understanding of the ecological and evolutionary dynamics of such symbioses, we now need to determine the combinations of mechanisms actually operating in the wild, in populations shaped by evolutionary history. We used a demographic population modeling approach to identify the mechanisms operating in a natural stand of an intermediate population (i.e. 50% of plants symbiotic) of the native grass Festuca eskia. We recorded demographic data in the wild over a period of three years, with manipulation of the soil resources for half the population. We developed two stage-structured matrix population models. The first model concerned either symbiotic or non-symbiotic plants. The second model included both symbiotic and non-symbiotic plants and took endophyte transmission rates into account. According to our models, symbiotic had a significantly higher population growth rate than non-symbiotic plants, and endophyte prevalence was about 58%. Endophyte transmission rates were about 0.67 or 0.87, depending on the growth stage considered. In the presence of nutrient supplementation, population growth rates were still significantly higher for symbiotic than for non-symbiotic plants, but endophyte prevalence fell to 0%. At vertical transmission rates below 0.10-0.20, no symbiosis was observed. Our models showed that a positive benefit of the endophyte and vertical transmission rates of about 0.6 could lead to the coexistence of symbiotic and non-symbiotic F. eskia plants. The positive effect of the symbiont on host is not systematically associated with high transmission rates of the symbiont over short time scales, in particular following an environmental change.

We focus on the identification of complete and recombined ribosomal DNA-bearing chromosomes, and the dynamics of chromosomal number and position of ribosomal DNA (rDNA) loci in the F2-F4 generations derived from the F1 hybrid of Festuca pratensis Huds. (2n = 4x = 28) × Lolium perenne L. (2n = 4x = 28). Lolium genomic DNA and rRNA genes were mapped by means of genomic and fluorescence in situ hybridization (GISH and FISH). The results revealed that plants of the three generations share various rDNA loci profiles with chromosome structural changes, possibly as a result of chromosomal inter- and intra-rearrangements. We observed an asymmetrical variation in the number of recombinant arms with and without rDNA loci between parental genomes. The Lolium genome was more affected by rearrangements in arms with rDNA loci, while Festuca was more affected in arms without them. Statistically significant differences between L. perenne and F. pratensis genomes concerned the number of recombined chromosomes without rDNA, and the number of recombined rDNA-bearing chromosomal arms of marked chromosomes, showing a tendency of F. pratensis genome-like chromosomes to be less stable, compared with L. perenne. We postulate a novel genome-dependent range and type of chromosome variation in plants of the F2-F4 generations derived from F. pratensis × L. perenne hybrid.

The effects of elevated CO2 and drought on ecophysiological parameters in grassland species have been examined, but few studies have investigated the effect of competition on those parameters under climate change conditions. The objective of this study was to determine the effect of elevated CO2 and drought on the response of plant water relations, gas exchange, chlorophyll a fluorescence and aboveground biomass in four grassland species, as well as to assess whether the type of competition modulates that response. Elevated CO2 in well-watered conditions increased aboveground biomass by augmenting CO2 assimilation. Drought reduced biomass by reducing CO2 assimilation rate via stomatal limitation and, when drought was more severe, also non-stomatal limitation. When plants were grown under the combined conditions of elevated CO2 and drought, drought limitation observed under ambient CO2 was reduced, permitting higher CO2 assimilation and consequently reducing the observed decrease in aboveground biomass. The response to climate change was species-specific and dependent on the type of competition. Thus, the response to elevated CO2 in well-watered grasses was higher in monoculture than in mixture, while it was higher in mixture compared to monoculture for forbs. On the other hand, forbs were more affected than grasses by drought in monoculture, while in mixture the negative effect of drought was higher in grasses than in forbs, due to a lower capacity to acquire water and mineral nutrients. These differences in species-level growth responses to CO2 and drought may lead to changes in the composition and biodiversity of the grassland plant community in future climate conditions., (© 2014 German Botanical Society and The Royal Botanical Society of the Netherlands.)

Tall fescue (Festuca arundinacea Schreb.) is the predominant cool-season perennial grass in the United States. It is widely used for both forage and turf purposes. This chapter describes a protocol that allows for the generation of a large number of transgenic tall fescue plants by Agrobacterium tumefaciens-mediated transformation. Embryogenic calli induced from caryopsis are used as explants for inoculation with A. tumefaciens. The Agrobacterium strain used is EHA105. Hygromycin phosphotransferase gene (hph) is used as the selectable marker, and hygromycin is used as the selection agent. Calli resistant to hygromycin are obtained after 4-6 weeks of selection. Soil-grown tall fescue plants can be regenerated 4-5 months after Agrobacterium tumefaciens-mediated transformation.

Background: Tall fescue (Festuca arundinacea Schreb.) is major cool-season forage and turf grass species worldwide, but high-temperature is a major environmental stress that dramatically threaten forage production and turf management of tall fescue. However, very little is known about the whole-genome molecular mechanisms contributing to thermotolerance. The objectives of this study were to analyzed genome-wide gene expression profiles in the leaves of two tall fescue genotypes, heat tolerant 'PI578718' and heat sensitive 'PI234881' using high-throughput RNA sequencing., Results: A total of 262 million high-quality paired-end reads were generated and assembled into 31,803 unigenes with an average length of 1,840 bp. Of these, 12,974 unigenes showed different expression patterns in response to heat stress and were categorized into 49 Gene Ontology functional subcategories. In addition, the variance of enrichment degree in each functional subcategory between PI578718 and PI234881 increased with increasing treatment time. Cell division and cell cycle genes showed a massive increase in transcript abundance in heat-stressed plants and more activated genes were detected in PI 578718 by Kyoto Encyclopedia of Genes and Genomes pathways analysis. Low molecular weight heat shock protein (LMW-HSP, HSP20) showed activated in two stressed genotypes and high molecular weight HSP (HMW-HSP, HSP90) just in PI578718. Assimilation such as photosynthesis, carbon fixation, CH4, N, S metabolism decreased along with increased dissimilation such as oxidative phosphorylation., Conclusions: The assembled transcriptome of tall fescue could serve as a global description of expressed genes and provide more molecular resources for future functional characterization analysis of genomics in cool-season turfgrass in response to high-temperature. Increased cell division, LMW/HMW-HSP, dissimilation and antioxidant transcript amounts in tall fescue were correlated with successful resistance to high temperature stress.

Heat stress affects a broad spectrum of cellular components and metabolism. The objectives of this study were to investigate the behavior of Photosystem II (PSII) in tall fescue (Festuca arundinacea Schreb) with various thermotolerance capacities and to broaden our comprehension about the relationship between thermotolerance and PSII function. Heat-tolerant and heat-sensitive accessions were incubated at 24 °C (control) and 46 °C (heat stress) for 5 h. The fluorescence transient curves (OJIP curves), slow Chl fluorescence kinetic, and light response curve were employed to study the behavior of PSII subjected to heat stress. After heat stress, performance index for energy conservation from photons absorbed by PSII antenna until the reduction of PSI acceptors (PITotal), the value of electrons produced per photon (a), and the maximal rate of electron transport (ETRmax) of heat-tolerant accessions were lower than those of heat-sensitive accessions. Relatively lower reactive oxygen species (ROS) contents were detected in heat-tolerant accessions. Simultaneously, there was a significant decline in the quantum yield of photochemical energy conversion in PS II (Y(II)), probability that a PSII Chl molecule functions as reaction center (γRC), and the increase of quantum yield for non-regulated non-photochemical energy loss (Y(NO)) in heat-tolerant accessions. Moreover, a significant inverse correlation between heat tolerance indexes (HTI) and Y(II) was observed. Therefore, maintaining a lower photochemical activity in heat-tolerant accessions could be a crucial strategy to improve their thermotolerance. This finding could be attributed to the structural difference in the reaction center, and for heat-tolerant accessions, it could simultaneously limit energy input into linear electron transport, and dissipate more energy through non-regulated non-photochemical energy loss processes.