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Background and Aims There is growing interest in the functional ecology of poikilohydric non-vascular photoautotrophs (NVPs), including 'cryptogamic' bryophytes and lichens. These organisms are structurally important in many ecosystems, contributing substantially to ecosystem function and services, while also being sensitive to climate change. Previous research has quantified the climate change response of poikilohydric NVPs using predictive bioclimatic models with standard climate variables including precipitation totals and temperature averages. This study aimed for an improved functional understanding of their climate change response based on their growth rate sensitivity to moisture and light. Methods We conducted a 24-month experiment to monitor lichen hydration and growth. We accounted for two well-known features in the ecology of poikilohydric NVPs, and exemplified here for a structurally dominant lichen epiphyte, Lobaria pulmonaria : (1) sensitivity to multiple sources of atmospheric moisture including rain, condensed dew-formation and water vapour; and (2) growth determined by the amount of time hydrated in the light, driving photosynthesis, referred to as the I wet hypothesis. Key Results First, we found that even within an oceanic high-rainfall environment, lichen hydration was better explained by vapour pressure deficit than precipitation totals. Second, growth at a monthly resolution was positively related to the amount of time spent hydrated in the light, and negatively related to the amount of time spent hydrated in the dark. Conclusions Using multimodel averaging to project growth models for an ensemble of future climate change scenarios, we demonstrated reduced net growth for L. pulmonaria by the late 21st century, explained by extended climate dryness and lichen desiccation for periods when there is otherwise sufficient light to drive photosynthesis. The results further emphasize a key issue of photoperiodism when constructing functionally relevant models to understand the risk of climate change, especially for poikilohydric NVPs. [ABSTRACT FROM AUTHOR]

Honeydew, a sugary excretion produced by sap‐feeding insects, plays a pivotal role in shaping intricate interactions between insects and plants. This review explains the multifaceted aspects of honeydew, beginning with an overview of its production mechanisms and factors influencing its variability across insect species and plant hosts. Exploring its composition, we examine the chemical components and nutritional aspects, highlighting variations based on insect species and plant sources. The impact of honeydew on microbial communities is explored, shedding light on its role in influencing the diversity and abundance of microorganisms. Furthermore, the review investigates how honeydew affects pest behaviour and population dynamics, elucidating plant responses to honeydew deposition. In the realm of biocontrol, we examine the intricate relationships between honeydew and natural enemies, considering potential implications for integrated pest management. Beyond these individual components, the paper discusses the broader ecological consequences of honeydew in ecosystems, emphasizing the interconnected relationships between insects, plants and microorganisms. The review concludes by identifying research gaps and suggesting future directions, recognizing the need for further investigation into areas with potential applications for agriculture and ecology. This review provides a comprehensive synthesis of the current understanding of honeydew's significance in insect–plant interactions, offering insights for both researchers and practitioners in the field. [ABSTRACT FROM AUTHOR]

Herbivore feeding often increases secondary metabolite production in plants. These herbivore‐induced plant proteins might end up in honeydew excreted by phloem‐feeding insects. This is important because honeydew is one of the most abundant and accessible carbohydrate sources for natural enemies in many agroecosystems and these proteins can thus mediate many tri‐trophic interactions. Here, we hypothesized that defensive metabolites induced in the phloem by herbivory accumulate in the honeydew excreted by phloem‐feeding insects and, consequently, affect the fitness of the herbivores' natural enemies that feed on it. We used a tri‐trophic system consisting of citrus plants, the mealybug Planococcus citri and its primary parasitoid Anagyrus vladimiri. First, we assessed A. vladimiri fitness when fed on P. citri honeydew. We then collected honeydew of seven phloem‐feeding insects, including P. citri, and analysed their protein content. Finally, we analysed the effect of superoxide dismutase (SOD), an antioxidant enzyme associated with plant defences that was commonly found in the analysed honeydews, on A. vladimiri fitness. The fitness of A. vladimiri increased when fed on honeydew compared to a sucrose‐based diet, demonstrating that honeydew can contain compounds that benefit natural enemies. Proteomic analyses showed that defence‐related plant proteins were present in honeydew of seven phloem‐feeding insects analysed. Among these, the enzyme SOD was present in honeydew of all of them. Moreover, the levels of SOD were 10‐fold higher in the phloem of plants infested by P. citri than in that of uninfested plants. SOD was also actively excreted in P. citri honeydew, and we proved that it increases the fecundity of the parasitoid A. vladimiri. We conclude that enzymatic proteins induced by herbivory in the phloem and involved in plant defence, accumulate in the honeydew excreted by phloem‐feeding insects and, contrary to the current paradigm, at least some of these can have positive effects on the third trophic level. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Erysiphe alphitoides is a species of powdery mildew responsible for the major foliar disease of oak trees, including Quercus robur. Infection with E. alphitoides leads to a reduction in the growth of the trees and in their ability to survive. This paper reports on the biochemical changes characteristic of defence responses in oak leaves with different infection area sizes, collected in July, August, and September during three growing seasons. The study highlights the effect of E. alphitoides infection on changes in the ascorbate-glutathione cycle, phenolic compound profile, and metal content (mineral distribution). Visible symptoms of pathogen infection appeared gradually in July, but the most intense biochemical plant responses in oak leaves were detected mainly in August and September. These responses included increased ascorbate-glutathione enzyme activities, phenolic compounds, and metal contents. In addition, microscopic analyses revealed a strong fluorescence signal of lignin in the epidermis of pathogen-infected leaves. The involvement of the studied compounds in the basic defence mechanisms of oak against E. alphitoides infection is discussed in the paper. [ABSTRACT FROM AUTHOR]

Jasmonic acid (JA) and salicylic acid (SA) phytohormone pathways are important regulators of stress tolerance. Knowledge regarding the diversity, phylogeny and functionality of wheat genes involved in JA and SA response is limited. Using Arabidopsis, rice and wheat genomic and wheat disease transcriptomic data, we deduced the size, phylogenetic diversity and pathogen‐responsiveness of seven hormone‐responsive gene families, and thus selected 14 candidates as potential hormone responsive gene markers. Gene‐specific expression studies assessed the impact of exogenous JA and SA on their transcriptional activation in leaves of two distinct wheat cultivars. RNAseq data were interrogated to assess their disease responsiveness and tissue‐specific expression. This study elucidated the number, phylogeny and pathogen‐responsiveness of wheat genes from seven families, including 12 TaAOS, 6 TaJAMyb, 256 TaWRKY group III, 85 TaPR1, 205 TaPR2, 76 TaPR3 and 124 TaPR5. This included the first description of the wheat AOS, JAMyb, PR2, PR3 and PR5 gene families. Gene expression studies delineated TaAOS1‐5B and TaJAMyb‐4A as JA‐responsive in leaves, but not significantly responsive to SA treatment, while TaWRKY45‐B was a SA‐ but not a JA‐responsive marker. Other candidate genes were either unresponsive or non‐specific to SA or JA. Our findings highlight that all seven gene families are greatly expanded in wheat as compared to other plants (up to 7.6‐fold expansion), and demonstrate disparity in the response to biotic stress between some homoeologous and paralogous sequences within these families. The SA‐ and JA‐responsive marker genes identified herein will prove useful tools to monitor these signalling pathways in wheat. [ABSTRACT FROM AUTHOR]

SUMMARY WHIRLY1 is a chloroplast‐nucleus located DNA/RNA‐binding protein with functions in development and stress tolerance. By overexpression of HvWHIRLY1 in barley, one line with a 10‐fold and two lines with a 50‐fold accumulation of the protein were obtained. In these lines, the relative abundance of the nuclear form exceeded that of the chloroplast form. Growth of the plants was shown to be compromised in a WHIRLY1 abundance‐dependent manner. Over‐accumulation of WHIRLY1 in chloroplasts had neither an evident impact on nucleoid morphology nor on the composition of the photosynthetic apparatus. Nevertheless, oeW1 plants were found to be compromised in the light reactions of photosynthesis as well as in carbon fixation. The reduction in growth and photosynthesis was shown to be accompanied by a decrease in the levels of cytokinins and an increase in the level of jasmonic acid. Gene expression analyses revealed that in nonstress conditions the oeW1 plants had enhanced levels of pathogen response (PR) gene expression indicating activation of constitutive defense. During growth in continuous light of high irradiance PR gene expression increased indicating that under stress conditions oeW1 are capable to further enhance defense. [ABSTRACT FROM AUTHOR]

Botrytis cinerea and Oidium neolycopersici represent two of the key fungal pathogens of tomato. In this study, 142 isolates were screened for their biocontrol potential against these pathogens. They were initially isolated from rhizospheric and from non-rhizospheric soil samples collected near healthy tomato plants grown in unheated greenhouses showing severe epidemics of grey mould in the Jijel region of Algeria. All the isolates were tested in vitro against B. cinerea using dual culture assays, and a subsample of 40 isolates (20 rhizospheric isolates and 20 non-rhizospheric isolates) was retained. The antagonistic effect of these candidates on spore germination of B. cinerea and their effect against O. neolycopersici and B. cinerea on tomato plants were then evaluated. The dual culture assays showed that non-rhizospheric bacteria were significantly more effective than rhizospheric bacteria in inhibiting the mycelial growth of B. cinerea. In planta, however, rhizospheric isolates showed significantly higher protective levels. This protective effect was significantly correlated to the ability of bacterial isolates to inhibit spore germination of B. cinerea. Taken together, these results allowed us to retain seven isolates with over 90% of efficacy against B. cinerea. These isolates were also able to protect tomato plants against O. neolycopersici, and they were identified as, P. argentinensis (SJ2), Serratia marcescens (SJ11), Pseudomonas lactis (SJ55), Pseudomonas veronii (RSAB3), Stenotrophomonas maltophilia (RTB17), Bacillus subtilis (SA14) and Bacillus toyonensis (SA87). This study showed promising results that could be exploited for a potential application of bacterial-based biocontrol agents efficient against both B. cinerea and O. neolycopersici. [ABSTRACT FROM AUTHOR]

Fraxinus ornus and F. excelsior are naturally occurring woodland trees and widely cultivated ornamental plants in Hungary. Leaves with powdery mildew symptoms observed unusually on adaxial side of leaves of F. ornus and F. excelsior were collected from two locations in Hungary. We identified the causing fungi based on their morphological characteristics and molecular phylogenetic analysis. Numerous chasmothecia were found on a part of the samples, which were spherical, 83–120 µm in diameter, and the apices of the appendages uncinated or spirally curved. Anamorphs were characterized by conidiophores developing conidia singly, and by hyphae with lobed appressoria, characteristic of Erysiphe spp. The internal transcribed spacer region of the nrDNA was amplified, and the BLAST searches showed 100% similarity with Erysiphe salmonii sequences in GenBank. In the phylogenetic analysis the sequences of the Hungarian samples grouped in one clade with the sequences of other E. salmonii specimens collected in Central and Eastern Europe and Asia. This is the first report of the non-native E. salmonii causing powdery mildew on Fraxinus sp. in Hungary. [ABSTRACT FROM AUTHOR]

Although blossom and honeydew honeys are produced from different nectar sources, it is very difficult to distinguish them. In this study, physicochemical and biochemical properties were compared to distinguish honeydew and blossom honeys obtained from different botanical sources. The honeys of pine (Pinus spp.) and oak (Quercus, spp.) were used as honeydew honey, and chestnut (Castania sativa L.) and highland honey were used as blossom honey. Turbidity, specific optical rotation (SOR) [α]20, electrical conductivity (EC), CIEL* a*b color parameters, and moisture and pH were assessed as physical parameters. Proline, invertase activity, sugar composition, total phenolic and flavonoid contents, and antioxidant capacity were used as biochemical properties. It was determined that SOR values were the most important parameters in distinguishing honeydew and blossom honeys. Turbidity stands out as a crucial factor in differentiating between pine and oak honeys. Except for chestnut honey, electrical conductivity, CIE color Lab values, and sugar profiles were identified as additional distinguishing factors among the tested honeys. [ABSTRACT FROM AUTHOR]

Although irrigation scheduling has been studied for diverse vegetable crops, much less attention has been given to irrigation scheduling for the seed crops on which these production systems rely. In spinach, for which irrigation scheduling needs are likely to vary greatly between seed and leaf production, this leaves seed producers without adequate resources to make irrigation scheduling decisions. Our research sought to fill this gap by evaluating two alternative irrigation scheduling strategies (a publicly available decision-support tool and soil moisture sensors) and four soil moisture thresholds for irrigation for their impacts on vegetative growth, marketable seed yield, seed quality, and the severity of Stemphylium leaf spot (caused by Stemphylium vesicarium and Stemphylium beticola), a common foliar disease of spinach, under sprinkler irrigation. We found that in all 3 years of the study, earlier and more frequent irrigation increased vegetative growth. However, marketable seed yield only increased relative to the control treatment based on farmers' standard irrigation practices in 1 of the 3 years--a year with an abnormally late planting date. This indicates that vegetative growth is more responsive than seed yield to earlier and more frequent irrigation, and that increases in vegetative growth do not translate directly to increased marketable seed yield. Contrary to the expected increase in Stemphylium leaf spot severity with increasing irrigation, the severity decreased in both years it was measured, likely as a result of the small stature of the spinach seed parent lines used in our study and opportunistic pathogenicity on moisture-stressed plants. These results provide a useful foundation from which spinach seed producers can make irrigation management decisions for their crops that underpin a valuable global industry. [ABSTRACT FROM AUTHOR]

We evaluated several horticultural cultivars and species of Monarda, a genus native to North America with a center of diversity in the Southeast and advertised as beneficial to wildlife, to assess landscape performance with respect to vegetative habit, flower production, and disease tolerance in Georgia Piedmont and montane habitats. We established two experimental sites: the State Botanical Garden of Georgia in Athens (USDA Zone 8b) and the Georgia Mountain Education and Research Center in Blairsville (USDA Zone 7b). We then tracked plant performance over 2 years after establishment. Our study included 10 samples of Monarda, representing five cultivars and four species. Estimated height and width at flowering showed M. bradburiana, M. Sugar BuzzVR Grape Gumball, and the M. punctata ecotypes were smaller than other tested taxa. M. fistulosa had the most flowers at the Blairsville site and equal flowering with M. punctata at the Athens location, but most taxa flowered for 2 to 3 months with ~100 flowering stems per stand. All samples were susceptible to powdery mildew, but M. bradburiana displayed the highest level of tolerance. Otherwise, cultivars tended to be more tolerant to powdery mildew than species. The observed variations in horticultural characteristics and performance highlight the high value of this genus for Georgia landscapes. [ABSTRACT FROM AUTHOR]

AbstractThe pathogen Plasmopara halstedii, causing downy mildew (DM), is a widespread sunflower disease which can be controlled by single dominant genes. Wild Helianthus annuus have been a valuable source of vertical resistance to control P. halstedii, but such resistance may eventually be overcome by new races of the pathogen. Alternatively, quantitative, or partial resistance, is more stable and may be combined with vertical resistance to prevent DM outbreaks. We assessed the responses of six populations of wild H. annuus naturalized in Argentina to race 710 of P. halstedii. We examined: 1) the aerial phenotype (including seedling death) using two damage scales and three disease indices, 2) the growth of the pathogen along the hypocotyls, and 3) the presence of the pathogen in the root system. We found that the evaluated sunflower wild populations had lower disease levels than the susceptible cultivated controls. A histologic analysis showed that the wild H. annuus seedlings showed cellular reactions (e.g. necrosis and the deposit of materials on the walls of invaded cells) to restrict the pathogen’s growth, allowing the identification of two possible types of resistance: type I, when the growth of the pathogen was limited to the base of the hypocotyls, and type II, when the pathogen managed to invade the entire length of the hypocotyls. The wild sunflower populations also showed differential responses to root infections. A quantitative or partial genetic resistance, rather than resistance based on major genes, seems to be operating in the sampled populations. The individuals found to be resistant in each population represent promising germplasm for sunflower breeding. [ABSTRACT FROM AUTHOR]

AbstractLagopsis supina (Xia Zhi Cao) is a widely distributed and cultivated herbal plant that has been extensively used as a traditional Chinese medicine, Tibetan medicine and Mongolian medicine for disease treatments for centuries. While the bioactive compounds of L. supina are extensively studied, the fungal pathogens of this plant are still obscure. In 2021, powdery mildew signs and symptoms were observed on leaves of L. supina in Xinxiang City, Henan Province, China. However, the causal pathogen had not been identified. Therefore, morphological characteristics and molecular analysis was applied to identify the powdery mildew pathogen. The sequence of the internal transcribed spacer (ITS) region of the fungus was obtained and showed 99.83% identity with the previously reported Neoerysiphe galeopsidis. The virulence of this phytopathogen on L. supina was confirmed by utilizing Koch’s postulates. Therefore, we identified the causal pathogen as N. galeopsidis. Based on biological and molecular characterization, this is the first comprehensive report of powdery mildew caused by N. galeopsidis on L. supina in central China. The occurrence of powdery mildew disease on L. supina may detract from the plant’s medical and ornamental value. The identification and confirmation of N. galeopsidis on L. supina expands the knowledge of this causal agent and will support efforts towards future control and management of powdery mildews. [ABSTRACT FROM AUTHOR]

AbstractIn the context of America’s active movement toward equality and the unity of races in the post-racist era, the Mountain Dew commercial demonstrates that the media realm continues to be dominated by the biases and stereotypes of racist origin. The study aimed to examine the case study of a Mountain Dew Commercial and critically documented its racial elements which sparked widespread criticism. Using Stuart Hall’s model of Encoding/Decoding, the study disclosed both the denotative and connotative meanings contained in the most racist advertisement in the history of commercials, as called by one of the critics. It examined the commercial from the viewpoint of the different levels of meanings and investigated the relationship between the portrayal of Black people and the ideological meanings that they carry in terms of the existing stereotype and its relation to other racial minorities. Also, the viewpoints of Tyler, the Creator, and Dr. Boyce Watkins were given which presented the arguments in favor and against racial content, aired by commercial entities. The study provided insight into how the idea of a post-racial society is discussed within the Black community, where experiences, education, and class play a major part in shaping competing racial politics. [ABSTRACT FROM AUTHOR]

Trichomes are common in plants from dry environments, and despite their recognized role in protection and defense, little is known about their role as absorptive structures and in other aspects of leaf ecophysiology. We combine anatomical and ecophysiological data to evaluate how trichomes affect leaf gas exchange and water balance during drought. We studied two congeneric species with pubescent leaves which co‐occur in Brazilian Caatinga: Croton blanchetianus (dense trichomes) and Croton adenocalyx (sparse trichomes). We found a novel foliar water uptake (FWU) pathway in C. blanchetianus composed of stellate trichomes and underlying epidermal cells and sclereids that interconnect the trichomes from both leaf surfaces. The water absorbed by these trichomes is redistributed laterally by pectin protuberances on mesophyll cell walls. This mechanism enables C. blanchetianus leaves to absorb water more efficiently than C. adenocalyx. Consequently, the exposure of C. blanchetianus to dew during drought improved its leaf gas exchange and water status more than C. adenocalyx. C. blanchetianus trichomes also increase their leaf capacity to reflect light and maintain lower temperatures during drought. Our results emphasize the multiple roles that trichomes might have on plant functioning and the importance of FWU for the ecophysiology of Caatinga plants during drought. Summary statement: We describe a novel pathway of foliar water absorption that involves stellate trichomes, sclereids and pectin protuberances that redistribute water inside the leaf. The absorption of dew water through this pathway benefits the ecophysiological performance of Caatinga plants during drought. [ABSTRACT FROM AUTHOR]

Powdery mildew significantly impacts the yield of natural rubber by being one of the predominant diseases that affect rubber trees. Accurate, non-destructive recognition of powdery mildew in the early stage is essential for the cultivation management of rubber trees. The objective of this study is to establish a technique for the early detection of powdery mildew in rubber trees by combining spectral and physicochemical parameter features. At three field experiment sites and in the laboratory, a spectroradiometer and a hand-held optical leaf-clip meter were utilized, respectively, to measure the hyperspectral reflectance data (350–2500 nm) and physicochemical parameter data of both healthy and early-stage powdery-mildew-infected leaves. Initially, vegetation indices were extracted from hyperspectral reflectance data, and wavelet energy coefficients were obtained through continuous wavelet transform (CWT). Subsequently, significant vegetation indices (VIs) were selected using the ReliefF algorithm, and the optimal wavelengths (OWs) were chosen via competitive adaptive reweighted sampling. Principal component analysis was used for the dimensionality reduction of significant wavelet energy coefficients, resulting in wavelet features (WFs). To evaluate the detection capability of the aforementioned features, the three spectral features extracted above, along with their combinations with physicochemical parameter features (PFs) (VIs + PFs, OWs + PFs, WFs + PFs), were used to construct six classes of features. In turn, these features were input into support vector machine (SVM), random forest (RF), and logistic regression (LR), respectively, to build early detection models for powdery mildew in rubber trees. The results revealed that models based on WFs perform well, markedly outperforming those constructed using VIs and OWs as inputs. Moreover, models incorporating combined features surpass those relying on single features, with an overall accuracy (OA) improvement of over 1.9% and an increase in F1-Score of over 0.012. The model that combines WFs and PFs shows superior performance over all the other models, achieving OAs of 94.3%, 90.6%, and 93.4%, and F1-Scores of 0.952, 0.917, and 0.941 on SVM, RF, and LR, respectively. Compared to using WFs alone, the OAs improved by 1.9%, 2.8%, and 1.9%, and the F1-Scores increased by 0.017, 0.017, and 0.016, respectively. This study showcases the viability of early detection of powdery mildew in rubber trees. [ABSTRACT FROM AUTHOR]

Summary: Biosynthesis of flavonoid aglycones and glycosides is well established. However, key genes involved in their catabolism are poorly understood, even though the products of hydrolysis and oxidation play important roles in plant resistance to biotic stress.Here, we report on catabolism of dihydrochalcones (DHCs), the most abundant flavonoids in domesticated apple and wild Malus. Two key genes, BGLU13.1 and PPO05, were identified by activity‐directed protein purification. BGLU13.1‐A hydrolyzed phlorizin, (the most abundant DHC in domesticated apple) to produce phloretin which was then oxidized by PPO05. The process differed in some wild Malus, where trilobatin (a positional isomer of phlorizin) was mainly oxidized by PPO05.The effects of DHC catabolism on apple resistance to biotic stresses was investigated using transgenic plants. Either directly or indirectly, phlorizin hydrolysis affected resistance to the phytophagous pest two‐spotted spider mite, while oxidation of trilobatin was involved in resistance to the biotrophic fungus Podosphaera leucotricha. DHC catabolism did not affect apple resistance to necrotrophic pathogens Valsa mali and Erwinia amylovara.These results suggest that different DHC catabolism pathways play different roles in apple resistance to biotic stresses. The role of DHC catabolism on apple resistance appeared closely related to the mode of invasion/damage used by pathogen/pest. [ABSTRACT FROM AUTHOR]

The barley powdery mildew fungus, Blumeria hordei (Bh), secretes hundreds of candidate secreted effector proteins (CSEPs) to facilitate pathogen infection and colonization. One of these, CSEP0008, is directly recognized by the barley nucleotide‐binding leucine‐rich‐repeat (NLR) receptor MLA1 and therefore is designated AVRA1. Here, we show that AVRA1 and the sequence‐unrelated Bh effector BEC1016 (CSEP0491) suppress immunity in barley. We used yeast two‐hybrid next‐generation interaction screens (Y2H‐NGIS), followed by binary Y2H and in planta protein–protein interactions studies, and identified a common barley target of AVRA1 and BEC1016, the endoplasmic reticulum (ER)‐localized J‐domain protein HvERdj3B. Silencing of this ER quality control (ERQC) protein increased Bh penetration. HvERdj3B is ER luminal, and we showed using split GFP that AVRA1 and BEC1016 translocate into the ER signal peptide‐independently. Overexpression of the two effectors impeded trafficking of a vacuolar marker through the ER; silencing of HvERdj3B also exhibited this same cellular phenotype, coinciding with the effectors targeting this ERQC component. Together, these results suggest that the barley innate immunity, preventing Bh entry into epidermal cells, requires ERQC. Here, the J‐domain protein HvERdj3B appears to be essential and can be regulated by AVRA1 and BEC1016. Plant disease resistance often occurs upon direct or indirect recognition of pathogen effectors by host NLR receptors. Previous work has shown that AVRA1 is directly recognized in the cytosol by the immune receptor MLA1. We speculate that the AVRA1 J‐domain target being inside the ER, where it is inapproachable by NLRs, has forced the plant to evolve this challenging direct recognition. [ABSTRACT FROM AUTHOR]

Introduction/Objective. Ayocote bean (Phaseolus coccineus) has potential as a source of resistance in breeding programs because it exhibits greater tolerance to plant pathogens than P. vulgaris. However, its sanitary characterization is insipient; therefore, the purpose of this work was to carry out an etiological-epidemiological diagnosis, with emphasis on presumptive symptoms of viral and phytoplasmic organisms, and a typical fungal signs of powdery mildew. Materials and Methods: A plot (50 x 62 m) of flowering Ayocote bean was selected. It was divided into 80 (8 x 10) quadrats (6 x 6 m) and 720 subquadrats (2 x 2 m). From 25 plants with powdery-mildew-type leaf symptoms, mycelium was collected with adhesive tape for light microscopy observation and taxonomic identification. Length-width measurements were made on 60 conidia. Pure mycelium collected in situ and ex situ from 1-5 leaflets/plant was used for genomic analysis by PCR with universal primers ITS1 and ITS4. Samples were sequenced in Macrogen Inc. Korea. A total of 63 plants and 121 trifoliate leaves with viral and phytoplasmic symptoms were collected by direct sampling. In 88/121 samples, genomic analysis was performed by PCR with universal primers for Potyvirus (1), Begomovirus (2), and Phytoplasmas (1). Sequence editing and analysis were performed in SeqAssem and BLASTn/GenBank. Phylogenetic constructions were developed in Mega 11 with MUSCLE, Maximum Likelihood (ML), and HKY substitution model (1000-Bootstrap). Putative powdery mildew severity (%), flower damage (%), Macrodactylus sp. adult density, and plant vigor (%) were evaluated in 80 quadrats (3subquadrats/quadrat) with App-Monitor®v1.1 configured with a 5-class scale. In GoldenSurfer® v10, Kriging geostatistical analysis was performed to determine the spatial interrelationship between these variables. Results: Erysiphe vignae was identified as associated with powdery mildew of P. coccineus. The fungus, with hyaline, ovoid to ellipsoid conidia measuring 31.74 ± 0.3419 µm x 15.11 ± 0.1579 µm, without the presence of fibrosin bodies, had 100% genomic homology. This is the first report in Mexico. With average July-August temperature and relative humidity of 16.3 °C (±5.8) and 92.8 % (±10.7), respectively, powdery mildew leaf incidence and severity were 65.3 and 22.7 % (±16.9, range: 0 - 66.5 %), respectively. The most inductive focus (60-80 % severity) had an aggregate e 4-quadrat pattern (96 m2, lag = 4 and s2-s = 450). Inoculum dispersal was significantly associated with dominant North-South winds and plant vigor (lag = 4 and s2-s = 470). Flower damage was inconclusive in its spatial association with powdery mildew and Macrodactylus sp. suggesting uncorrelated events. No Potyvirus, Begomovirus, or Phytoplasmas were detected associated with yellowing, leaf distortion, mosaic, internode shortening, and other symptoms observed in situ. This confirms the relative tolerance/resistance reported for P. coccineus. Conclusion: E. vignae (Erysiphales: Erysiphaceae) associated with P. coccineus is reported for the first time in Mexico with moderate to intense epidemic level, which indicates its susceptible condition to this fungus. However, negative results for Potyvirus, Begomovirus, and Phytoplasmas, validate the apparent tolerance/resistance of P. coccineus to these organisms. [ABSTRACT FROM AUTHOR]

BACKGROUND: In order to explore the effect of ozone sterilization treatment on tomato disease control and increase fruit setting rate, this study took 906 pink fruit tomato as test material, used a small ozone generator to carry out ozone treatment single‐factor test, and then selected orthogonal table to guide the ozone treatment combination. The effects of different ozone treatment concentration, ozone treatment duration and ozone treatment times on the growth, disease and fruit setting rate of potted tomato were analyzed. RESULTS: Different ozone treatment had effects on leaf mildew, gray mold and fruit setting rate of tomato. The influence degree of three factors on leaf mildew, gray mold and fruit setting rate was from large to small, a > b > c, a > c > b, b > a > c. A quadratic regression model was established with the control effect of tomato leaf mildew, gray mold and fruit setting rate as response values, and the optimal parameter combination was determined: The ozone treatment concentration was 0.0465 g kg−1, the ozone treatment time was 30 min, and the ozone treatment times were twice a week. In this case, the control efficiency of tomato leaf mildew was 95.02%, the control effect of gray mold was 99.49%, and the fruit setting rate was 76.5%. The test parameters were accurate and reliable. CONCLUSION: The ozone sterilization method proposed in this article is safe and green, and can provide theoretical support for the recovery and reconstruction of tomato disease in a glasshouse. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

As an important habitat for microorganisms, the phyllosphere has a great impact on plant growth and health, and changes in phyllosphere microorganisms are closely related to the occurrence of leaf diseases. However, there remains a limited understanding regarding alterations to the microbial community in the phyllosphere resulting from pathogen infections. Here, we analyzed and compared the differences in phyllosphere microorganisms of powdery mildew cucumber from three disease severity levels (0% < L1 < 30%, 30% ≤ L2 < 50%, L3 ≥ 50%, the number represents the lesion coverage rate of powdery mildew on leaves). There were significant differences in α diversity and community structure of phyllosphere communities under different disease levels. Disease severity altered the community structure of phyllosphere microorganisms, Rosenbergiella, Rickettsia , and Cladosporium accounted for the largest proportion in the L1 disease grade, while Bacillus, Pantoea, Kocuria , and Podosphaera had the highest relative abundance in the L3 disease grade. The co-occurrence network analysis of the phyllosphere microbial community indicated that the phyllosphere bacterial community was most affected by the severity of disease. Our results suggested that with the development of cucumber powdery mildew, the symbiotic relationship between species was broken, and the entire bacterial community tended to compete. [ABSTRACT FROM AUTHOR]

Background: Aconitum carmichaelii Debx. has been widely used as a traditional medicinal herb for a long history in China. It is highly susceptible to various dangerous diseases during the cultivation process. Downy mildew is the most serious leaf disease of A. carmichaelii, affecting plant growth and ultimately leading to a reduction in yield. To better understand the response mechanism of A. carmichaelii leaves subjected to downy mildew, the contents of endogenous plant hormones as well as transcriptome sequencing were analyzed at five different infected stages. Results: The content of 3-indoleacetic acid, abscisic acid, salicylic acid and jasmonic acid has changed significantly in A. carmichaelii leaves with the development of downy mildew, and related synthetic genes such as 9-cis-epoxycarotenoid dioxygenase and phenylalanine ammonia lyase were also significant for disease responses. The transcriptomic data indicated that the differentially expressed genes were primarily associated with plant hormone signal transduction, plant-pathogen interaction, the mitogen-activated protein kinase signaling pathway in plants, and phenylpropanoid biosynthesis. Many of these genes also showed potential functions for resisting downy mildew. Through weighted gene co-expression network analysis, the hub genes and genes that have high connectivity to them were identified, which could participate in plant immune responses. Conclusions: In this study, we elucidated the response and potential genes of A. carmichaelii to downy mildew, and observed the changes of endogenous hormones content at different infection stages, so as to contribute to the further screening and identification of genes involved in the defense of downy mildew. [ABSTRACT FROM AUTHOR]

Given difficulties with modelling radiation fog and the similarity of meteorological conditions linked to dewfall and frost we investigated the formation of dew, frost and fog. For a site in the UK seven years of data were analysed representing high‐resolution atmospheric profiles and dew meter measurements for radiation nights with stable conditions. Classical dewfall occurs by condensation when the surface is below the dew point and cooler than the air above. However, the profiles show that, in the absence of fog, typically dew and frost form with the surface warmer than the immediately overlying air due to lifted temperature minima (LTMs) at about 0.15 m. Observations of aerosol number density and average hydrated radii show that aerosol optical extinction (and hence their radiative effect) is weakly but significantly correlated with the intensity of LTMs. Low wind speed on stable nights allows settling of aerosols which radiatively cool the air near the ground more quickly than the surface cools – thus creating LTMs. In the presence of LTMs typically dew and frost form not by condensation, but by occult deposition of water droplets onto the canopy and ground. Among radiation fog observations, 91% are associated with light near‐surface winds and LTMs. When the rate of removal of suspended water droplets by occult deposition generating dew or frost is too slow, then build‐up of droplets in the air just above the surface leads to the formation of radiation fog. Future modelling should allow for the accumulation of near‐surface aerosols and their radiative effects during stable nights to represent the formation of LTMs. Modelling of typical dew and frost will require representation of occult deposition. Assessing rates of occult deposition compared to rates of generation of suspended water droplets is needed to forecast the onset of radiation fog formed near the ground. [ABSTRACT FROM AUTHOR]

A high-quality genome sequence from an Indian isolate of Blumeria graminis f. sp. tritici Wtn1, a persistent threat in wheat farming, was obtained using a hybrid method. The assembly of over 9.24 million DNA-sequence reads resulted in 93 contigs, totaling a 140.61 Mb genome size, potentially encoding 8480 genes. Notably, more than 73.80% of the genome, spanning approximately 102.14 Mb, comprises retro-elements, LTR elements, and P elements, influencing evolution and adaptation significantly. The phylogenomic analysis placed B. graminis f. sp. tritici Wtn1 in a distinct monocot-infecting clade. A total of 583 tRNA anticodon sequences were identified from the whole genome of the native virulent strain B. graminis f. sp. tritici, which comprises distinct genome features with high counts of tRNA anticodons for leucine (70), cysteine (61), alanine (58), and arginine (45), with only two stop codons (Opal and Ochre) present and the absence of the Amber stop codon. Comparative InterProScan analysis unveiled "shared and unique" proteins in B. graminis f. sp. tritici Wtn1. Identified were 7707 protein-encoding genes, annotated to different categories such as 805 effectors, 156 CAZymes, 6102 orthologous proteins, and 3180 distinct protein families (PFAMs). Among the effectors, genes like Avra10, Avrk1, Bcg-7, BEC1005, CSEP0105, CSEP0162, BEC1016, BEC1040, and HopI1 closely linked to pathogenesis and virulence were recognized. Transcriptome analysis highlighted abundant proteins associated with RNA processing and modification, post-translational modification, protein turnover, chaperones, and signal transduction. Examining the Environmental Information Processing Pathways in B. graminis f. sp. tritici Wtn1 revealed 393 genes across 33 signal transduction pathways. The key pathways included yeast MAPK signaling (53 genes), mTOR signaling (38 genes), PI3K-Akt signaling (23 genes), and AMPK signaling (21 genes). Additionally, pathways like FoxO, Phosphatidylinositol, the two-component system, and Ras signaling showed significant gene representation, each with 15–16 genes, key SNPs, and Indels in specific chromosomes highlighting their relevance to environmental responses and pathotype evolution. The SNP and InDel analysis resulted in about 3.56 million variants, including 3.45 million SNPs, 5050 insertions, and 5651 deletions within the whole genome of B. graminis f. sp. tritici Wtn1. These comprehensive genome and transcriptome datasets serve as crucial resources for understanding the pathogenicity, virulence effectors, retro-elements, and evolutionary origins of B. graminis f. sp. tritici Wtn1, aiding in developing robust strategies for the effective management of wheat powdery mildew. [ABSTRACT FROM AUTHOR]

Key message: VyPUB21 plays a key role during the defense against powdery mildew in grapes. Ubiquitin-ligating enzyme (E3), a type of protein widely found in plants, plays a key role in their resistance to disease. Yet how E3 participates in the disease-resistant response of Chinese wild grapevine (Vitis yeshanensis) remains unclear. Here we isolated and identified a U-box type E3 ubiquitin ligase, VyPUB21, from V. yeshanensis. This gene’s expression level rose rapidly after induction by exogenous salicylic acid (SA), jasmonic acid (JA), and ethylene (ETH) and powdery mildew. In vitro ubiquitination assay results revealed VyPUB21 could produce ubiquitination bands after co-incubation with ubiquitin, ubiquitin-activating enzyme (E1), and ubiquitin-conjugating enzyme (E2); further, mutation of the conserved amino acid site in the U-box can inhibit the ubiquitination. Transgenic VyPUB21 Arabidopsis had low susceptibility to powdery mildew, and significantly fewer conidiophores and spores on its leaves. Expression levels of disease resistance-related genes were also augmented in transgenic Arabidopsis, and its SA concentration also significantly increased. VyPUB21 interacts with VyNIMIN and targets VyNIMIN protein hydrolysis through the 26S proteasome system. Thus, the repressive effect of the NIMIN–NPR complex on the late systemic acquired resistance (SAR) gene was attenuated, resulting in enhanced resistance to powdery mildew. These results indicate that VyPUB21 encoding ubiquitin ligase U-box E3 activates the SA signaling pathway, and VyPUB21 promotes the expression of late SAR gene by degrading the important protein VyNIMIN of SA signaling pathway, thus enhancing grape resistance to powdery mildew. [ABSTRACT FROM AUTHOR]

In viticulture, downy mildew is one of the most common diseases that, if not adequately treated, can diminish production yield. However, the uncontrolled use of pesticides to alleviate its occurrence can pose significant risks for farmers, consumers, and the environment. This paper presents a new framework for the early detection and estimation of the mildew's appearance in viticulture fields. The framework utilizes a protocol for the real-time acquisition of drones' high-resolution RGB images and a cloud-docker-based video or image inference process using object detection CNN models. The authors implemented their framework proposition using open-source tools and experimented with their proposed implementation on the debina grape variety in Zitsa, Greece, during downy mildew outbursts. The authors present evaluation results of deep learning Faster R-CNN object detection models trained on their downy mildew annotated dataset, using the different object classifiers of VGG16, ViTDet, MobileNetV3, EfficientNet, SqueezeNet, and ResNet. The authors compare Faster R-CNN and YOLO object detectors in terms of accuracy and speed. From their experimentation, the embedded device model ViTDet showed the worst accuracy results compared to the fast inferences of YOLOv8, while MobileNetV3 significantly outperformed YOLOv8 in terms of both accuracy and speed. Regarding cloud inferences, large ResNet models performed well in terms of accuracy, while YOLOv5 faster inferences presented significant object classification losses. [ABSTRACT FROM AUTHOR]

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a severe disease that affects the yield and quality of wheat. Popularization of resistant cultivars in production is the preferred strategy to control this disease. In the present study, the Chinese wheat breeding line Jimai 809 showed excellent agronomic performance and high resistance to powdery mildew at the whole growth stage. To dissect the genetic basis for this resistance, Jimai 809 was crossed with the susceptible wheat cultivar Junda 159 to produce segregation populations. Genetic analysis showed that a single dominant gene, temporarily designated PmJM809, conferred the resistance to different Bgt isolates. PmJM809 was then mapped on the chromosome arm 2BL and flanked by the markers CISSR02g-1 and CIT02g-13 with genetic distances 0.4 and 0.8 cM, respectively, corresponding to a physical interval of 704.12–708.24 Mb. PmJM809 differed from the reported Pm genes on chromosome arm 2BL in origin, resistance spectrum, physical position and/or genetic diversity of the mapping interval, also suggesting PmJM809 was located on a complex interval with multiple resistance genes. To analyze and screen the candidate gene(s) of PmJM809, six genes related to disease resistance in the candidate interval were evaluated their expression patterns using an additional set of wheat samples and time-course analysis post-inoculation of the Bgt isolate E09. As a result, four genes were speculated as the key candidate or regulatory genes. Considering its comprehensive agronomic traits and resistance findings, PmJM809 was expected to be a valuable gene resource in wheat disease resistance breeding. To efficiently transfer PmJM809 into different genetic backgrounds, 13 of 19 closely linked markers were confirmed to be suitable for marker-assisted selection. Using these markers, a series of wheat breeding lines with harmonious disease resistance and agronomic performance were selected from the crosses of Jimai 809 and several susceptible cultivars. [ABSTRACT FROM AUTHOR]

Wheat powdery mildew is a fungal disorder caused by Blumeria graminis f. sp. tritici (Bgt) and is a severe and significant threat to the yield and quality of its host. The most practical and environmentally friendly approach to controlling this disease is through resistance gene identification to develop resistant varieties. Wild germplasm relatives of wheat are a valuable reservoir of genes contributing to resistance against powdery mildew. In our study, we identified the Aegilops tauschii germplasm "KU-2013", exhibiting seedling resistance to Bgt isolate E09 following hexaploidization. Genetic analysis and chromosomal localization of the powdery mildew resistance gene in doubled haploid (DH) KU-2013 indicated that the disease resistance gene in DHKU-2013 is governed by a dominant gene situated in 5DS, tentatively named PmKu-2013. Following the analysis of PmKu-2013 relative to the genes at the Pm2 locus, it was inferred that PmKu-2013 represented a distinct novel gene separate from Pm2. Using molecular marker analysis, PmKu-2013 was found to be ultimately mapped between the sdau5DS5-3 and sdau5DS6-1 markers, with genetic distances of 0.6 cM and 1.3 cM, respectively. Using markers tightly linked to PmKu-2013, the genotypes of core wheat varieties from various regions were identified, laying the foundation for the transfer and utilization of PmKu-2013 in molecular-assisted selection (MAS) for breeding. [ABSTRACT FROM AUTHOR]

Powdery mildew is a severe wheat disease that causes substantial yield losses in wheat production worldwide. The Chinese wheat landrace Changanhongmai (CAHM) exhibits high resistance to the physiological race E09 of powdery mildew. In this study, we characterized the powdery mildew resistance gene in CAHM, and developed molecular markers for wheat marker-assisted selection. To investigate the genetic characteristics of this resistant gene, we developed F1 plants, F2 generation population, and F2:3 families by crossing CAHM with SY225 (Shaanyou '225' as susceptible male parent). Genetic analysis demonstrated that all F1 plants were resistant to the disease, while the ratio of resistant to susceptible plants was 3: 1 in both the F2 population and F2:3 families, indicating that CAHM is inherited in a manner of a single dominant powdery mildew resistance gene, which was tentatively designated as PmCAHM. By using bulk segregation analysis, we constructed a genetic map encompassing Xgwm273, Xwmc626, Xgwm11, Xgwm18, Xgdm28, Xgpw7812, Xgpw5195, Xwmc694, and PmCAHM. Among these markers, Xgpw7812 and Xgpw5195 are flanking markers that are tightly linked to PmCAHM at a genetic distance of 2.5 cM and 8.4 cM, respectively. Furthermore, nullisomic-tetrasomic analysis revealed that PmCAHM is located on chromosome 1B. These results indicate that PmCAHM differs from the internationally recognized powdery mildew resistance genes in both location and source. In addition, a new germplasm/line NW1748 with stronger powdery mildew resistance and large grains was developed from the cross and backcross populations of Fengyou1718 (FY1718)/CAHM/5/FY 1718. Therefore, PmCAHM can serve as a novel powdery mildew resistance source for breeding of wheat by using NW1748 as the donor in the future. [ABSTRACT FROM AUTHOR]

Introgression of resistance genes from wild or related species is a common strategy to improve disease resistance of wheat cultivars. Pm17 is a gene that confers powdery mildew resistance in wheat. It encodes an NLR type of immune receptor and was introgressed from rye to wheat as part of the 1RS chromosome arm translocation several decades ago. So far it has not been possible to separate Pm17 from its co-introgressed rye genes due to suppressed recombination. Here we tested in the field transgenic Bobwhite wheat overexpressing Pm17 without any other rye genes. Four transgenic events showed high levels of PM17 protein accumulation, strong powdery mildew resistance, and no pleiotropic effects during three field seasons. We used a combined approach of transgene insertion and cross-breeding to generate lines co-expressing Pm17 and Pm3 , or Pm17 and Pm8. Blumeria graminis f. sp. tritici infection tests confirmed additive, race-specific resistance of the two pyramided transgenes in lines Pm17+Pm3b and Pm17+Pm8. Furthermore, pyramided lines showed strong powdery mildew resistance during three field seasons. We conclude that the combination of overexpressed NLR genes from the extended gene pool broadens and diversifies wheat disease resistance. [ABSTRACT FROM AUTHOR]

Downy mildew of grapevine (Vitis vinifera), caused by the oomycete Plasmopara viticola, is an important disease that is present in cultivation areas worldwide, and using resistant varieties provides an environmentally friendly alternative to fungicides. DOWNY MILDEW RESISTANT 6 (DMR6) from Arabidopsis is a negative regulator of plant immunity and its loss of function confers resistance to downy mildew. In grapevine, DMR6 is present in two copies, named VvDMR6-1 and VvDMR6-2. Here, we describe the editing of VvDMR6-1 in embryogenic calli using CRISPR/Cas9 and the regeneration of the edited plants. All edited plants were found to be biallelic and chimeric, and whilst they all showed reduced growth compared with non-transformed control plants, they also had reduced susceptibility to P. viticola. Comparison between mock-inoculated genotypes showed that all edited lines presented higher levels of salicylic acid than controls, and lines subjected to transformation presented higher levels of cis-resveratrol than controls. Our results identify VvDMR6-1 as a promising target for breeding grapevine cultivars with improved resistance to downy mildew. [ABSTRACT FROM AUTHOR]

Plant diseases tend to be more serious under conditions of high-temperature/high-humidity (HTHH) than under moderate conditions, and hence disease resistance under HTHH is an important determinant for plant survival. However, how plants cope with diseases under HTHH remains poorly understood. In this study, we used the pathosystem consisting of pepper (Capsicum annuum) and Ralstonia solanacearum (bacterial wilt) as a model to examine the functions of the protein mildew resistance locus O 1 (CaMLO1) and U-box domain-containing protein 21 (CaPUB21) under conditions of 80% humidity and either 28 °C or 37 °C. Expression profiling, loss- and gain-of-function assays involving virus-induced gene-silencing and overexpression in pepper plants, and protein–protein interaction assays were conducted, and the results showed that CaMLO1 acted negatively in pepper immunity against R. solanacearum at 28 °C but positively at 37 °C. In contrast, CaPUB21 acted positively in immunity at 28 °C but negatively at 37 °C. Importantly, CaPUB21 interacted with CaMLO1 under all of the tested conditions, but only the interaction in response to R. solanacearum at 37 °C or to exposure to 37 °C alone led to CaMLO1 degradation, thereby turning off defence responses against R. solanacearum at 37 °C and under high-temperature stress to conserve resources. Thus, we show that CaMLO1 and CaPUB21 interact with each other and function distinctly in pepper immunity against R. solanacearum in an environment-dependent manner. [ABSTRACT FROM AUTHOR]

This paper presents a novel sound event detection (SED) system for rare events occurring in an open environment. Wavelet multiresolution analysis (MRA) is used to decompose the input audio clip of 30 seconds into five levels. Wavelet denoising is then applied on the third and fifth levels of MRA to filter out the background. Significant transitions, which may represent the onset of a rare event, are then estimated in these two levels by combining the peak-finding algorithm with the K-medoids clustering algorithm. The small portions of one-second duration, called 'chunks' are cropped from the input audio signal corresponding to the estimated locations of the significant transitions. Features from these chunks are extracted by the wavelet scattering network (WSN) and are given as input to a support vector machine (SVM) classifier, which classifies them. The proposed SED framework produces an error rate comparable to the SED systems based on convolutional neural network (CNN) architecture. Also, the proposed algorithm is computationally efficient and lightweight as compared to deep learning models, as it has no learnable parameter. It requires only a single epoch of training, which is 5, 10, 200, and 600 times lesser than the models based on CNNs and deep neural networks (DNNs), CNN with long short-term memory (LSTM) network, convolutional recurrent neural network (CRNN), and CNN respectively. The proposed model neither requires concatenation with previous frames for anomaly detection nor any additional training data creation needed for other comparative deep learning models. It needs to check almost 360 times fewer chunks for the presence of rare events than the other baseline systems used for comparison in this paper. All these characteristics make the proposed system suitable for real-time applications on resource-limited devices. [ABSTRACT FROM AUTHOR]

Downy mildew caused by Sclerospora graminicola is a systemic disease that affects the yield and quality of foxtail millet. This obligate biotrophic oomycete manipulates host physiology and immune processes through numerous effectors. A thorough comprehension of effector biology is crucial to unravel disease mechanisms and understand host plant resistance. In this study, bioinformatic analyses revealed 498 potentially secreted proteins in S. graminicola, of which 62 were identified as RXLR effectors; 46 RXLR‐encoding genes exhibited upregulated expression during the early stages of infection. To elucidate the functions of these secreted proteins, a heterogeneous expression system was developed using Nicotiana benthamiana. Twenty‐one RXLR effectors secreted by S. graminicola were transiently expressed in N. benthamiana, of which four could suppress INF1‐triggered cell death. Various defence responses in N. benthamiana were attenuated, including inhibition of defence gene expression, reduction of reactive oxygen species (ROS) accumulation and diminished callose deposition. The expression of SG_RXLR41 also enhanced the growth of Phytophthora capsici on N. benthamiana leaves. These findings indicate that S. graminicola facilitates infection and expansion through the secretion of multiple RXLR effectors, and SG_RXLR41 is an important virulence‐related effector that is involved in manipulating plant immunity by suppressing cell death. [ABSTRACT FROM AUTHOR]

An integrated control program for peaches and apples powdery mildew was evaluatedboth Burg Al-Arab and South of Tahreer regions. In the first season, the efficiency of the program’s fungicides were tested in terms of the number of sprays and the most appropriate time to repeat the sprays, as well as the best effective fungicides. It was found that they all treatments were effective in controlling the disease. The best time to repeat spraying was from seven up to 10 days. In the second season, the chosen fungicides were evaluated compared with the farm fungicides individually, and the general control (sprayed with water only). On the other hand, evaluation of essential oils and fertilizers were done individually. The results showed the efficiency of systemic fungicide (Scor), copper and sulfur (preventive fungicides) and cinnamon oil and chitosan as Eco - friendly alternatives in controlling the disease. In the third season all tested fungicides used at the dormancy stage of trees at first January before buds swelling, data showed that all fungicides indicate high effect in decreasing the disease comparing with control at the in first of May compared to the control (100% disease severity). The tested fungicides gave 2.9% and 3.3% in case of peach at Borg Al-Arab and South of Tahreer respectively and 6%, 8.6% in apple at Borg Al-Arab and South of Tahreer respectively. At the fourth season all treatments combined in the integrated program were done at beginning spray (at 8 January while dormancy stage of trees) on apple. The tested program showed significant reduction on peach and apple powdery mildew compared to the control (100% disease severity) at the end of tested program comparing with the farm of tested program in case of peach and apple at Borg Al-Arab and South of Tahreer respectively, in May before harvest. In the fifth season the same tested program applied at t at the first of November during the winter tree service. The tested program was effective in control peach and apple powdery disease in locations. [ABSTRACT FROM AUTHOR]

Honeydew from Hemipteran insects serves as carbohydrate source to beneficial insects but also to various microorganisms. Microbial volatile organic compounds (mVOCs) may play diverse roles in herbivore–microbe–natural enemy interactions. However, the functional significance of mVOCs from aphid honeydew remains largely unclear. In this study, a total of seven cultivable bacteria from Sitobion miscanthi honeydew have been isolated and identified based on 16S rRNA technique, which included Lysinibacillus fusiformis, Erwinia aphidicola, E. tasmaniensis, Acinetobacter bereziniae, Klebsiella quasipneumoniae subsp. Similipneumoniae, Staphylococcus capitis and Bacillus safensis subsp. safensis. One bacterial strain, L. fusiformis MH1, was found to be most attractive to Aphidius gifuensis parasitic wasp in Y-tube olfactometer. Two compounds, namely 1-ethyl-2-methylbenzene and 2-butyl-1-octanol, were emitted from L. fusiformis MH1 and were attractive to A. gifuensis and identified by using coupled gas chromatography–electroantennography and coupled gas chromatography with mass spectrometry. Application of bacterial and mVOCs formulations in crop field resulted in significant aphid abundance decrease associated with higher parasitism rates compared with control. Our results indicated that some microbes in aphid honeydew could manipulate the herbivore–natural enemy interactions and could be developed as a novel alternative for environmentally friendly biological control of aphids. [ABSTRACT FROM AUTHOR]

Background: Powdery mildew (PM) is one of the important soybean diseases, and host resistance could practically contribute to soybean PM management. To date, only the Rmd locus on chromosome (Chr) 16 was identified through traditional QTL mapping and GWAS, and it remains unclear if the bulk segregant RNA-Seq (BSR-Seq) methodology is feasible to explore additional PM resistance that might exist in other varieties. Results: BSR-Seq was applied to contrast genotypes and gene expressions between the resistant bulk (R bulk) and the susceptible bulk (S bulk), as well as the parents. The ∆(SNP-index) and G' value identified several QTL and significant SNPs/Indels on Chr06, Chr15, and Chr16. Differentially expressed genes (DEGs) located within these QTL were identified using HISAT2 and Kallisto, and allele-specific primers (AS-primers) were designed to validate the accuracy of phenotypic prediction. While the AS-primers on Chr06 or Chr15 cannot distinguish the resistant and susceptible phenotypes, AS-primers on Chr16 exhibited 82% accuracy prediction with an additive effect, similar to the SSR marker Satt431. Conclusions: Evaluation of additional AS-primers in the linkage disequilibrium (LD) block on Chr16 further confirmed the resistant locus, derived from the resistant parental variety 'Kaohsiung 11' ('KS11'), not only overlaps with the Rmd locus with unique up-regulated LRR genes (Glyma.16G213700 and Glyma.16G215100), but also harbors a down-regulated MLO gene (Glyma.16G145600). Accordingly, this study exemplified the feasibility of BSR-Seq in studying biotrophic disease resistance in soybean, and showed the genetic makeup of soybean variety 'KS11' comprising the Rmd locus and one MLO gene. [ABSTRACT FROM AUTHOR]

Spinach (Spinacia oleracea) is an economically important leafy vegetable grown in the United States and world-wide. The downy mildew pathogen, Peronospora effusa (Pfs), is a major biotic constraint impacting spinach production and quality. The use of resistant cultivars is an economical and environmentally-friendly management option especially in organic production systems. As new races of the pathogen continue to appear, there is a need to continue to select for resistance to the emerging races. The objectives of this study were to evaluate a set of spinach hybrids and F2 breeding populations for resistance to Pfs race 5 to develop a better understanding of the genetics of downy mildew resistance. Also, we screened 39 commercial spinach cultivars for resistance to a recently identified race, Pfs race 19. The genetics of resistance to Pfs 5 was determined by greenhouse inoculations of F1 progeny (individual crosses between near isogenic lines, NIL3 or NIL1 and susceptible genotype, Viroflay) and F2 population progeny (cross between Califlay and susceptible Viroflay). Two hybrids were examined for resistance to Pfs 5. The results indicated that resistance conferred at the RPF1 or the RPF3 loci in a heterozygous (Rr) condition to Pfs 5 was completely dominant. Also, Chi-square analysis of the segregation pattern in the F2 population showed that resistance to Pfs race 5 was conferred by a single dominant gene. A total of 22 out of 39 spinach commercial cultivars were resistant to the newly reported Pfs race 19 and could be used in breeding programs to develop new cultivars with resistance to Pfs 19. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize the effects of barley powdery mildew infection on wheat via the evolution and dynamics of chloroplasts and oxidative processes based on in vivo measurements of ultra-weak photon emission, parallel measurement of chlorophyll and ascorbic acid content, and molecular identification of the pathogen. The results showed the temporal dynamics of the evolution of ultra-weak photon emission signals that were evidently different for healthy and powdery mildew-infested wheat leaves. In the dark, the ceasing of delayed fluorescence signal made it possible to visualize the ultra-weak luminescence signal as well. Both delayed fluorescence and ultra-weak luminescence signals were characteristic of stress symptoms induced by powdery mildew that was further strengthened by the changes of chlorophyll and ascorbic acid content as typical stress analytical parameters. The presented data and parameterization enabled the identification of stress induction due to powdery mildew infestation in wheat, which should be investigated in detail in the future for fine-tuning our measurements, even by using other species and increasing the length of the measurement in order to increase its specificity. The changes in R2 values are suitable for monitoring the changes of plant stress response. The measurement of fluorescence and luminescence leads to a greater comprehension of the underlying photon emission-related processes, both in general and in the case of powdery mildew infestation. [ABSTRACT FROM AUTHOR]

This article comments on: Wu Y, Sexton WK, Zhang Q, Bloodgood D, Wu Y, Hooks C, Coker F, Vasquez A, Wei C-I, Xiao S. 2024. Leaf abaxial immunity to powdery mildew in Arabidopsis is conferred by multiple defense mechanisms. Journal of Experimental Botany 75, 1465–1478. [ABSTRACT FROM AUTHOR]

Powdery mildew fungi are obligate biotrophic pathogens that only invade plant epidermal cells. There are two epidermal surfaces in every plant leaf: the adaxial (upper) side and the abaxial (lower) side. While both leaf surfaces can be susceptible to adapted powdery mildew fungi in many plant species, there have been observations of leaf abaxial immunity in some plant species including Arabidopsis. The genetic basis of such leaf abaxial immunity remains unknown. In this study, we tested a series of Arabidopsis mutants defective in one or more known defense pathways with the adapted powdery mildew isolate Golovinomyces cichoracearum UCSC1. We found that leaf abaxial immunity was significantly compromised in mutants impaired for both the EDS1/PAD4- and PEN2/PEN3-dependent defenses. Consistently, expression of EDS1–yellow fluorescent protein and PEN2–green fluorescent protein fusions from their respective native promoters in the respective eds1-2 and pen2-1 mutant backgrounds was higher in the abaxial epidermal cells than in the adaxial epidermal cells. Altogether, our results indicate that leaf abaxial immunity against powdery mildew in Arabidopsis is at least partially due to enhanced EDS1/PAD4- and PEN2/PEN3-dependent defenses. Such transcriptionally pre-programmed defense mechanisms may underlie leaf abaxial immunity in other plant species such as hemp and may be exploited for engineering adaxial immunity against powdery mildew fungi in crop plants. [ABSTRACT FROM AUTHOR]

Hydathodes are usually associated with water exudation in plants. However, foliar water uptake (FWU) through the hydathodes has long been suspected in the leaf‐succulent genus Crassula (Crassulaceae), a highly diverse group in southern Africa, and, to our knowledge, no empirical observations exist in the literature that unequivocally link FWU to hydathodes in this genus. FWU is expected to be particularly beneficial on the arid western side of southern Africa, where up to 50% of Crassula species occur and where periodically high air humidity leads to fog and/or dew formation. To investigate if hydathode‐mediated FWU is operational in different Crassula species, we used the apoplastic fluorescent tracer Lucifer Yellow in combination with different imaging techniques. Our images of dye‐treated leaves confirm that hydathode‐mediated FWU does indeed occur in Crassula and that it might be widespread across the genus. Hydathodes in Crassula serve as moisture‐harvesting structures, besides their more common purpose of guttation, an adaptation that has likely played an important role in the evolutionary history of the genus. Our observations suggest that ability for FWU is independent of geographical distribution and not restricted to arid environments under fog influence, as FWU is also operational in Crassula species from the rather humid eastern side of southern Africa. Our observations point towards no apparent link between FWU ability and overall leaf surface wettability in Crassula. Instead, the hierarchically sculptured leaf surfaces of several Crassula species may facilitate FWU due to hydrophilic leaf surface microdomains, even in seemingly hydrophobic species. Overall, these results confirm the ecophysiological relevance of hydathode‐mediated FWU in Crassula and reassert the importance of atmospheric humidity for some arid‐adapted plant groups. Summary Statement: This study demonstrates that foliar water uptake (FWU) through hydathodes, previously suspected but unconfirmed, is indeed operational in most Crassula species. This phenomenon occurs across different habitats and highlights the ecophysiological relevance of atmospheric humidity for these plants. [ABSTRACT FROM AUTHOR]

We have recovered disease-symptomatic monocot leaves from the middle Siwalik (late Miocene; 12–8 Ma) sedimentary strata of Himachal Pradesh, western Himalaya, India. Information about disease symptoms linked to fossil monocot leaves, however, is lacking. The present study therefore aims to elucidate their identity through the analysis of morphological characteristics of the plant pathogenic fungi (causal agent) associated with these disease symptoms. Black mildew disease caused by foliicolous fungal fossil-genus Meliolinites Selkirk ex Janson. and Hills (fossil Meliolaceae) is detected on infected host Siwalik monocot leaves. In the study presented here, we provide formal descriptions and illustrations for the fossil-genus. The pathogen Meliolinites is recognized by the presence of appressoria, phialides, mycelial seta, black non-ostiolate ascomata, and four-septate, five-celled ascospores. This is the first report of melioloid fungus causing black mildew disease on fossil monocot leaves. Here, we also reconstruct a possible disease cycle of black mildew pathogen on Siwalik monocot leaves. The in-situ evidence of Meliolinites on the monocot leaf cuticles indicates the possible existence of a biotrophic relationship in Himachal sub-Himalaya's ancient warm and humid tropical forest during the time of deposition. • Evidence of disease-symptomatic monocot leaves recovered from Himachal Siwalik. • First evidence of melioloid fungus causing black mildew disease on fossil monocot leaves. • Reconstruct a possible disease cycle of Meliolinites on host monocot. • Existence of a biotrophic relationship between monocot and Meliolinites since Miocene. [ABSTRACT FROM AUTHOR]

The obligate biotrophic fungal pathogen Blumeria graminis forma specialis tritici (B.g. tritici) is the causal agent of wheat powdery mildew disease. The TOPLESS-related 1 (TPR1) corepressor regulates plant immunity, but its role in regulating wheat resistance against powdery mildew remains to be disclosed. Herein, TaTPR1 was identified as a positive regulator of wheat post-penetration resistance against powdery mildew disease. The transient overexpression of TaTPR1.1 or TaTPR1.2 confers wheat post-penetration resistance powdery mildew, while the silencing of TaTPR1.1 and TaTPR1.2 results in an enhanced wheat susceptibility to B.g. tritici. Furthermore, Defense no Death 1 (TaDND1) and Defense no Death 2 (TaDND2) were identified as wheat susceptibility (S) genes facilitating a B.g. tritici infection. The overexpression of TaDND1 and TaDND2 leads to an enhanced wheat susceptibility to B.g. tritici, while the silencing of wheat TaDND1 and TaDND2 leads to a compromised susceptibility to powdery mildew. In addition, we demonstrated that the expression of TaDND1 and TaDND2 is negatively regulated by the wheat transcriptional corepressor TaTPR1. Collectively, these results implicate that TaTPR1 positively regulates wheat post-penetration resistance against powdery mildew probably via suppressing the S genes TaDND1 and TaDND2. [ABSTRACT FROM AUTHOR]

Our previous research showed that a powdery mildew resistant barley line (MvHV07-17) maintains its resistance to Blumeria hordei (Bh) even if plants are exposed to a long-term high temperature of 35°C for 120 h before Bh inoculation, whereas such high temperature pretreatment further increases susceptibility to infection in the susceptible barley line MvHV118-17. In the present study, we extended this approach using short-term high-temperature water treatment (49°C for 30 s) to determine how it affects powdery mildew resistance in these barley lines. We found that this short-term heat shock (HS) impaired plant defense responses, as reflected by development of Bh colonies and visible necrotic spots on leaves of MvHV07-17, which does not develop visible symptoms upon Bh inoculation under optimal growth conditions. In contrast, both HS and long-term heat stress enhanced susceptibility to Bh in MvHV118-17 plants. These results were supported by the measurement of Bh biomass using a qPCR method. Furthermore, microscopic examinations showed that HS elevated the rate of successful Bh penetration events and the spread of cell death in the surrounding mesophyll area and allowed for colony formation and sporulation in resistant barley, whereas early and effective plant defense responses, such as papilla formation and single-cell epidermal hypersensitive response, were significantly reduced. Furthermore, we found that the accumulation of hydrogen peroxide in both resistant and susceptible barley was correlated with susceptibility induced by HS and long-term heat-stress. This study may contribute to a better understanding of plant defense responses to Bh in barley exposed to heat. [ABSTRACT FROM AUTHOR]

Frequent fungicide applications are required to manage grapevine powdery mildew (Erysiphe necator). However, this practice is costly and has led to widespread fungicide resistance. A method of monitoring in-field fungicide efficacy could help growers maximize spray-interval length, thereby reducing costs and the rate of fungicide resistance emergence. The goal of this study was to evaluate if hyperspectral sensing in the visible to shortwave infrared range (400 to 2,400 nm) can quantify foliar fungicide efficacy on grape leaves. Commercial formulations of metrafenone, Bacillus mycoides isolate J (BmJ), and sulfur were applied on Chardonnay grapevines in vineyard or greenhouse settings. Foliar reflectance was measured with handheld hyperspectral spectroradiometers at multiple days post-application. Fungicide efficacy was estimated as a proxy for fungicide residue and disease control measured with the Blackbird microscopy imaging robot. Treatments could be differentiated from the untreated control with an accuracy of 73.06% for metrafenone, 67.76% for BmJ, and 94.10% for sulfur. The change in spectral reflectance was moderately correlated with the cube root of the area under the disease progress curve for metrafenone- and sulfur-treated samples (R2 = 0.38 and 0.36, respectively) and with sulfur residue (R2 = 0.42). BmJ treatment impacted foliar physiology by enhancing the leaf mass/area and reducing the nitrogen and total phenolic content as estimated from spectral reflectance. The results suggest that hyperspectral sensing can be used to monitor in-situ fungicide efficacy, and the prediction accuracy depends on the fungicide and the time point measured. The ability to monitor in-situ fungicide efficacy could facilitate more strategic fungicide applications and promote sustainable grapevine protection. [ABSTRACT FROM AUTHOR]

Background: Plant defense against the pathogens can be induced by using different defense inducers. Plants can be treated with elicitors for fast and more intense mobilization of defense responses which can enhance the resistance against biotic or abiotic stresses. Methods: The present study has been undertaken to evaluate the synergistic effect of different plant defense inducing chemical (Salicylic acid, Isonicotinic acid, Oxalic acid and Chitosan) and biological (Trichoderma harzianum and Pseudomonas fluorescens) elicitors. Enzyme activity was expressed as the increase in absorbance using spectrophotometer. Result: Among all the treatments the maximum PAL activity (35.58 mg/g of fresh weight) was found in case of oxalic acid but after 48 hrs its activity reduced drastically. Next to oxalic acid Pseudomonas fluorescens (31.38 mg/g of fresh weight), chitosan + Trichoderma harzianum (29.38 mg/g of fresh weight) and chitosan + Pseudomonas fluorescens (27.89 mg/g of fresh weight) showed the maximum enzyme activity. The PPO activity reached the highest at 96 hr after challenge inoculation in case of chitosan + Trichoderma harzianum (9.74 µmol/min/mg/protein) treated plants followed by Trichoderma harzianum (3.53 µmol/min/mg/protein) alone. the maximum PO activity (49.12 µmol/min/mg/protein) was found in case of chitosan + Pseudomonas fluorescens treated plants followed by chitosan (42.48 µmol/min/mg/protein) after 72 hrs. the maximum phenolics (27.53 mg/gm of fresh weight) was found in case of chitosan + Pseudomonas fluorescens after 48 hrs of treatment. [ABSTRACT FROM AUTHOR]

Cytochrome P450s are a large family of protein-encoding genes in plant genomes, many of which have not yet been comprehensively characterized. Here, a novel P450 gene, CYP82D47, was isolated and functionally characterized from cucumber (Cucumis sativus L.). Quantitative real-time reverse-transcription polymerase chain reaction analysis revealed that CYP82D47 expression was triggered by salicylic acid (SA) and ethephon (ETH). Expression analysis revealed a correlation between CYP82D47 transcript levels and plant defense responses against powdery mildew (PM) and Fusarium oxysporum f. sp. cucumerinum (Foc). Although no significant differences were observed in disease resistance between CYP82D47-RNAi and wild-type cucumber, overexpression (OE) of CYP82D47 enhanced PM and Foc resistance in cucumber. Furthermore, the expression levels of SA-related genes (PR1, PR2, PR4, and PR5) increased in CYP82D47-overexpressing plants 7 days post fungal inoculation. The levels of ETH-related genes (EIN3 and EBF2) were similarly upregulated. The observed enhanced resistance was associated with the upregulation of SA/ETH-signaling-dependent defense genes. These findings indicate the crucial role of CYP82D47 in pathogen defense in cucumber. CYP82D47-overexpressing cucumber plants exhibited heightened susceptibility to both diseases. The study results offer important insights that could aid in the development of disease-resistant cucumber cultivars and elucidate the molecular mechanisms associated with the functions of CYP82D47. [ABSTRACT FROM AUTHOR]

To investigate the changes in fungal community structure with mold occurrence during the industrial fermentation of cigar tobacco leaves, Dexue No. 1 cigar tobacco leaf was chosen as the test material, and counting methods in microbiology and Illumina MiSeq high-throughput sequencing technology were used to analyze the changes in mold content and fungal community structure of normal and moldy cigar tobacco leaf samples during the industrial fermentation. The results indicated that compared to norml tobacco leaves, on the 30th day of fermentation, the mold content in moldy cigar tobacco leaves was the highest (8.3x104 CFU/ g), the richness and diversity of species were the lowest, and the number of OTUs was the least. At the level of the phylum, Ascomycota was an absolute advantageous phylum on day 30 of fermentation, with an average relative abundance of 99.82%. At the level of the genus, Aspergillus was the main genus in the entire fermentation process, and the average relative abundance on day 30 of fermentation was the largest (92.32%). The 30 d mildewy cigar tobacco leaf and other samples had a significant difference in species composition compared to normal tobacco leaves. Among them, Aspergillus was both an advantageous genus and a differential genus, and the average relative abundance of various samples was the highest. [ABSTRACT FROM AUTHOR]

Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a devastating disease that seriously threatens wheat yield and quality. To control this disease, host resistance is the most effective measure. Compared with the resistance genes from common wheat, alien resistance genes can better withstand infection of this highly variable pathogen. Development of elite alien germplasm resources with powdery mildew resistance and other key breeding traits is an attractive strategy in wheat breeding. In this study, three wheat-rye germplasm lines YT4-1, YT4-2, and YT4-3 were developed through hybridization between octoploid triticale and common wheat, out of which the lines YT4-1 and YT4-2 conferred adult-plant resistance (APR) to powdery mildew while the line YT4-3 was susceptible to powdery mildew during all of its growth stages. Using genomic in situ hybridization, multi-color fluorescence in situ hybridization, multi-color GISH, and molecular marker analysis, YT4-1, YT4-2, and YT4-3 were shown to be cytogenetically stable wheat-rye 6R addition and T1RS(1BL translocation line, 6RL ditelosomic addition and T1RS(1BL translocation line, and T1RS(1BL translocation line, respectively. Compared with previously reported wheat-rye derivative lines carrying chromosome 6R, YT4-1 and YT4-2 showed stable APR without undesirable pleiotropic effects on agronomic traits. Therefore, these novel wheat-rye 6R derivative lines are expected to be promising bridge resources in wheat disease breeding. [ABSTRACT FROM AUTHOR]