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Abstract Floating seedling cultivation technique is a novel seedling method in cotton and it provides an ideal model to study cotton growing under waterlogging stress. Morphological character and proteomic profile of the primary root from the seedling cultured by the new technology were evaluated in this study. Compared to seedlings cultured by the traditional method, the diameter of the taproot from floating technology is small at all five seedling stages from one-leaf stage to five-leaf stage. There are similar changes between the thickness of cortex and diameter of stele, which increased from the one- to the two-leaf stage but decreased from the two- to the five-leaf stage. At the one-leaf stage, the number and volume of mitochondria in the primary root-tip cells were less than those in the control. At the two-leaf stage, there was significantly less electron-dense material in the primary root-tip cells than those in the control group. From the one- to the two-leaf stage, the vacuole volume was significantly smaller than that in the control. Total 28 differentially expressed proteins were revealed from aquatic and control group roots of cotton seedlings at the three-leaf stage by two-dimensional electrophoresis, which included 24 up-regulated and four down-regulated proteins. The relative expression of the phosphoglycerate kinase (PGK) gene in aquatic roots increased from the one- to the four-leaf stage but declined rapidly from the four- to the five-leaf stage. The relative expression of the 14–3-3b gene tended to decrease from the one- to the five-leaf stage. The PGK and 14–3-3b genes were specifically expressed in the aquatic roots at the three-leaf stage. In brief, these changes induced waterlogging resistance in the aquatic roots of cotton seedlings in the floating nursery, thereby causing the roots to adapt to the aquatic environment, promoting the growth and development of cotton seedlings.

'Hangju' is a variety of Chrysanthemum × morifolium Ramat. with both edible and medicinal value, cultivated as a traditional Chinese medicine for four centuries. The cultivation of 'Hangju' is currently at risk due to waterlogging, yet there is a lack of comprehensive understanding regarding its response to waterlogging stress. This study compared the waterlogging-tolerant 'Hangju' variety Enhanced Waterlogging Tolerance (EWT) with the waterlogging-sensitive variety CK ('zaoxiaoyangju'). EWT exhibited a more developed aeration tissue structure and demonstrated rapid growth regarding the adventitious roots following waterlogging. The time-course transcriptome analysis indicated that EWT could swiftly adjust the expression of the genes involved in the energy metabolism signaling pathways to acclimate to the waterlogged environment. Through WGCNA analysis, we identified Integrase-Type DNA-Binding Protein (CmTINY2) as a key factor in regulating the waterlogging tolerance in EWT. CmTINY2, a transcription factor belonging to the ethylene-responsive factor (ERF) subfamily III, operated within the nucleus and activated downstream gene expression. Its role in enhancing the waterlogging tolerance might be linked to the control of the stomatal aperture via the Ethylene-Responsive Element (ERE) gene. In summary, our research elucidated that the waterlogging tolerance displayed by EWT is a result of a combination of the morphological structure and molecular regulatory mechanisms. Furthermore, the study of the functions of CmTINY2 from ERF subfamily III also broadened our knowledge of the role of the ERF genes in the waterlogging signaling pathways. [ABSTRACT FROM AUTHOR]

Background: This study aimed to determine the effects of different waterlogging duration imposed at the V2 leaf stage and assess the impact of waterlogging on maize growth during the recovery period, identify susceptible and tolerant lines and traits conferring tolerance to waterlogging at the early seedling stage. Methods: The study was arranged in a Split-plot RCBD and replicated three times. Intercharacter and waterlogging durations to maize growth parameters were correlated to determine the degree of the linear relationship using Pearson's product moments correlation and simple linear regression analysis. Result: The result shows that the different waterlogging durations negatively influenced the maize growth parameters regarding plant height and root length. These parameters became shorter and did not recover after waterlogging stress was removed. Therefore, plant height and root length are traits sensitive to waterlogging stress. The USM Var 10, BRK and T. Monkayo obtained a high degree of leaf greenness, heaviest shoot and root dry matter compared to other evaluated maize lines. Maize with greener leaves, taller plant height, longer root length and high total dry matter accumulation could be a good criterion in selecting a parent material in the maize waterlogging breeding program. [ABSTRACT FROM AUTHOR]

Abstract Background Heterosis breeding is one of the most important breeding methods for chrysanthemum. To date, the genetic mechanisms of heterosis for waterlogging tolerance in chrysanthemum are still unclear. This study aims to analyze the expression profiles and potential heterosis-related genes of two hybrid lines and their parents with extreme differences in waterlogging tolerance under control and waterlogging stress conditions by RNA-seq. Results A population of 140 F1 progeny derived from Chrysanthemum indicum (Nanchang) (waterlogging-tolerant) and Chrysanthemum indicum (Nanjing) (waterlogging-sensitive) was used to characterize the extent of genetic variation in terms of seven waterlogging tolerance-related traits across two years. Lines 98 and 95, respectively displaying positive and negative overdominance heterosis for the waterlogging tolerance traits together with their parents under control and waterlogging stress conditions, were used for RNA-seq. In consequence, the maximal number of differentially expressed genes (DEGs) occurred in line 98. Gene ontology (GO) enrichment analysis revealed multiple stress-related biological processes for the common up-regulated genes. Line 98 had a significant increase in non-additive genes under waterlogging stress, with transgressive up-regulation and paternal-expression dominant patterns being the major gene expression profiles. Further, GO analysis identified 55 and 95 transgressive up-regulation genes that overlapped with the up-regulated genes shared by two parents in terms of responses to stress and stimulus, respectively. 6,640 genes in total displaying maternal-expression dominance patterns were observed in line 95. In addition, 16 key candidate genes, including SAP12, DOX1, and ERF017 which might be of significant importance for the formation of waterlogging tolerance heterosis in line 98, were highlighted. Conclusion The current study provides a comprehensive overview of the root transcriptomes among F1 hybrids and their parents under waterlogging stress. These findings lay the foundation for further studies on molecular mechanisms underlying chrysanthemum heterosis on waterlogging tolerance.

Plant plasma membrane H+-ATPase is a transport protein that is generally located on the plasma membrane and generates energy by hydrolyzing adenosine triphosphate (ATP) to pump hydrogen ions (H+) in the cytoplasm out of the cell against a concentration gradient. The plasma membrane H+-ATPases in plants are encoded by a multigene family and potentially play a fundamental role in regulating plant responses to various abiotic stresses, thus contributing to plant adaptation under adverse conditions. To understand the characteristics of the plasma membrane H+-ATPase family in peach (Prunus persica), this study analyzed the plasma membrane H+-ATPase family genes in peach. The results showed that there were 27 members of the plasma membrane H+-ATPase family in peach with amino acid sequences ranging from 943 to 1327. Subcellular localization showed that 23 of the 27 members were located on the cell membrane, and the phylogenetic tree analysis indicated that peach plasma membrane H+-ATPase members were divided into five groups. There were four genes with tandem repeat relationships, and six plasma membrane H+-ATPase genes were differentially expressed after 5 days of flooding and under non-flooding conditions based on the RNA-seq and RT-qPCR analyses. This study also investigated the characteristics and possible functions of the plasma membrane H+-ATPase family members in peach. The results provide theoretical support for further studies on their biological functions in peach. [ABSTRACT FROM AUTHOR]

Main conclusions: A novel image-based screening method for precisely identifying genotypic variations in rapeseed RSA under waterlogging stress was developed. Five key root traits were confirmed as good indicators of waterlogging and might be employed in breeding, particularly when using the MFVW approach. Waterlogging is a vital environmental factor that has detrimental effects on the growth and development of rapeseed (Brassica napus L.). Plant roots suffer from hypoxia under waterlogging, which ultimately confers yield penalty. Therefore, it is crucially important to understand the genetic variation of root system architecture (RSA) in response to waterlogging stress to guide the selection of new tolerant cultivars with favorable roots. This research was conducted to investigate RSA traits using image-based screening techniques to better understand how RSA changes over time during waterlogging at the seedling stage. First, we performed a t-test by comparing the relative root trait value between four tolerant and four sensitive accessions. The most important root characteristics associated with waterlogging tolerance at 12 h are total root length (TRL), total root surface area (TRSA), total root volume (TRV), total number of tips (TNT), and total number of forks (TNF). The root structures of 448 rapeseed accessions with or without waterlogging showed notable genetic diversity, and all traits were generally restrained under waterlogging conditions, except for the total root average diameter. Additionally, according to the evaluation and integration analysis of 448 accessions, we identified that five traits, TRL, TRSA, TRV, TNT, and TNF, were the most reliable traits for screening waterlogging-tolerant accessions. Using analysis of the membership function value (MFVW) and D-value of the five selected traits, 25 extremely waterlogging-tolerant materials were screened out. Waterlogging significantly reduced RSA, inhibiting root growth compared to the control. Additionally, waterlogging increased lipid peroxidation, accompanied by a decrease in the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). This study effectively improves our understanding of the response of RSA to waterlogging. The image-based screening method developed in this study provides a new scientific guidance for quickly examining the basic RSA changes and precisely predicting waterlogging-tolerant rapeseed germplasms, thus expanding the genetic diversity of waterlogging-tolerant rapeseed germplasm available for breeding. [ABSTRACT FROM AUTHOR]

Background: Heterosis breeding is one of the most important breeding methods for chrysanthemum. To date, the genetic mechanisms of heterosis for waterlogging tolerance in chrysanthemum are still unclear. This study aims to analyze the expression profiles and potential heterosis-related genes of two hybrid lines and their parents with extreme differences in waterlogging tolerance under control and waterlogging stress conditions by RNA-seq. Results: A population of 140 F1 progeny derived from Chrysanthemum indicum (Nanchang) (waterlogging-tolerant) and Chrysanthemum indicum (Nanjing) (waterlogging-sensitive) was used to characterize the extent of genetic variation in terms of seven waterlogging tolerance-related traits across two years. Lines 98 and 95, respectively displaying positive and negative overdominance heterosis for the waterlogging tolerance traits together with their parents under control and waterlogging stress conditions, were used for RNA-seq. In consequence, the maximal number of differentially expressed genes (DEGs) occurred in line 98. Gene ontology (GO) enrichment analysis revealed multiple stress-related biological processes for the common up-regulated genes. Line 98 had a significant increase in non-additive genes under waterlogging stress, with transgressive up-regulation and paternal-expression dominant patterns being the major gene expression profiles. Further, GO analysis identified 55 and 95 transgressive up-regulation genes that overlapped with the up-regulated genes shared by two parents in terms of responses to stress and stimulus, respectively. 6,640 genes in total displaying maternal-expression dominance patterns were observed in line 95. In addition, 16 key candidate genes, including SAP12, DOX1, and ERF017 which might be of significant importance for the formation of waterlogging tolerance heterosis in line 98, were highlighted. Conclusion: The current study provides a comprehensive overview of the root transcriptomes among F1 hybrids and their parents under waterlogging stress. These findings lay the foundation for further studies on molecular mechanisms underlying chrysanthemum heterosis on waterlogging tolerance. [ABSTRACT FROM AUTHOR]

Pulse production is decreased when grown on waterlogged soil in rice‐based cropping. This study evaluated four pulse crops—grass pea, field pea, cowpea and lentil—to find out their responses to waterlogging (WL) stress at emergence and vegetative stages. The treatment levels at emergence were drained control, 4‐, 7‐ and 10‐day WL, while in the vegetative stage they were drained control, 6‐, 10‐ and 14‐day WL. In the emergence stage, %emergence was significantly reduced as WL duration increased. After 10‐day WL, emergence was reduced to 65% for grass pea, 30% for field pea, 5% for lentil and 7% for cowpea. At the vegetative stage, in both the WL and recovery phases, the WL treatment reduced plant height, tap root length, shoot and root dry mass compared to those in drained control with a significant difference in crops. In recovery as compared to the WL phase at 14‐day WL, the chlorophyll content was increased 15% in cowpea and 14% in grass pea but decreased in field pea (26%) and lentil (35%). Similarly, in the recovery phase at 14‐day WL, shoot relative growth rates (RGRs) of cowpea, grass pea, field pea and lentil were 20, 66, 10 and 5 mg plant−1 d−1; which were 66%, 70%, 8% and 14% of drained control, respectively. The RGR of root at 14‐day WL was also higher in cowpea and grass pea with the rate of 13.8 and 16 mg−1 plant−1 d−1, respectively; in sharp contrast to a reduction of −4.3 mg−1 plant−1 d−1 in field pea and −3.9 mg−1 plant−1 d−1 for lentil than drained control. Furthermore, the higher number of adventitious roots was found in cowpea (14) and grass (9) pea than in field pea (6) and lentil (4). Comparison between growth stages, grass pea was tolerant to WL in both stages. Cowpea was WL sensitive at emergence, but tolerant to vegetative stage. Field pea was moderately tolerant to emergence but was sensitive at vegetative stage. Lentil was sensitive at WL at both stages. These novel insights will allow the fitting of winter pulses to various cropping systems according to the perceived risk of WL at various growth stages. [ABSTRACT FROM AUTHOR]

In order to explore the effect of fertilization patterns on the growth of rapeseed seedlings under waterlogging stress, three fertilization patterns (conventional fertilization, supplemental organic fertilization, and supplemental microbial fertilization) were set up using the variety Xiangyou 708 as the material, and waterlogging treatment was carried out during the seedling stage of rapeseed. The effects of fertilization patterns on the growth of rapeseed seedlings and rhizosphere microorganisms under waterlogging stress were investigated. The results showed that all three fertilization patterns exhibited that waterlogging stress inhibited the growth of rapeseed seedlings, inhibited root activity, and changed the structure of rhizosphere bacterial community structure. However, supplemental organic and microbial fertilization better promoted the growth of rapeseed seedlings, reduced the impact of waterlogging stress on the growth of rapeseed seedlings, and accelerated the recovery of rapeseed seedlings after waterlogging stress. Under normal water supply, supplemental organic fertilization enriched P_Bacteroidota, P_Actinobacteriota, P_Chloroflexi, and G_Flavisolibacter in the rhizosphere soil of rapeseed, while supplemental microbial fertilization enriched P_Bacteroidota and G_Flavisolibacter in the rhizosphere soil of rapeseed. After 7 days of waterlogging treatment, supplemental organic fertilization enriched P_Verrucomicrobiota in the rhizosphere soil of rapeseed, while supplemental microbial fertilization enriched P_Actinobacteriota, G_SC-I-84, and G_Ellin6067 in the rhizosphere soil of rapeseed. The enrichment of these bacteria may be related to the growth promotion and waterlogging tolerance of rapeseed. This study provides evidence that microbial and organic fertilizer can promote the growth of rapeseed and enhance its waterlogging tolerance, as well as evidence that some rhizosphere microorganisms have a potential role in promoting the growth and waterlogging tolerance of rapeseed. [ABSTRACT FROM AUTHOR]

Black-grass (Alopecurus myosuroides) is one of the most problematic agricultural weeds of Western Europe, causing significant yield losses in winter wheat (Triticum aestivum) and other crops through competition for space and resources. Previous studies link black-grass patches to water-retaining soils, yet its specific adaptations to these conditions remain unclear. We designed pot-based waterlogging experiments to compare 13 biotypes of black-grass and six cultivars of wheat. These showed that wheat roots induced aerenchyma when waterlogged whereas aerenchyma-like structures were constitutively present in black-grass. Aerial biomass of waterlogged wheat was smaller, whereas waterlogged black-grass was similar or larger. Variability in waterlogging responses within and between these species was correlated with transcriptomic and metabolomic changes in leaves of control or waterlogged plants. In wheat, transcripts associated with regulation and utilisation of phosphate compounds were upregulated and sugars and amino acids concentrations were increased. Black-grass biotypes showed limited molecular responses to waterlogging. Some black-grass amino acids were decreased and one transcript commonly upregulated was previously identified in screens for genes underpinning metabolism-based resistance to herbicides. Our findings provide insights into the different waterlogging tolerances of these species and may help to explain the previously observed patchiness of this weed's distribution in wheat fields. Black-grass is a problematic weed of winter wheat. To better understand if waterlogging tolerance increases its weediness, we conducted controlled waterlogging studies comparing the physiology and molecular responses of black-grass and wheat. These revealed differences in roots and aerial tissues within and between species. Molecular analyses showed that wheat mounts a significant molecular response, altering gene expression and metabolites with waterlogging, whereas black-grass showed minimal responses to waterlogging despite its apparent tolerance. This article belongs to the Collection Flooding Stress and Hypoxic Responses in Plants. [ABSTRACT FROM AUTHOR]

Basic helix-loop-helix (bHLH) proteins are important in abiotic stress control. Here, a specific bHLH transcription factor gene, CabHLH18, from a strong waterlogging-tolerant pepper cultivar, 'ZHC2', was successfully cloned. The CabHLH18 gene presented a coding sequence length of 1,056 bp, encoding 352 amino acids, and the protein was the closest to Capsicum annuum XM016694561.2 protein. The CabHLH18 protein was located in the nucleus. The transformation of the CabHLH18 overexpression vector into the plumules of hot peppers, 'DFZJ' and 'ZHC1', exhibited 21.37% and 22.20% efficiency, respectively. The root length, plant height, and fresh weight of the 'DFZJ' overexpression lines were greater than those of wild-type (WT) plants under waterlogging conditions. Compared with the WT plants, the overexpression lines generally showed greater contents of water, the amino acid, proline, soluble sugar, root viability, and superoxide dismutase activity, but lower malondialdehyde content under waterlogging conditions. Plant fresh weight, amino acids, proline, and soluble sugar levels of the overexpression lines were 39.17%, 45.03%, 60.67%, and 120.18% greater, respectively, compared with the WT plants at 24 h after waterlogging stress. Therefore, the CabHLH18 gene could be implicated in conferring waterlogging tolerance in hot peppers and holds promise for enhancing their overall waterlogging tolerance. [ABSTRACT FROM AUTHOR]

Climate change poses a significant threat to agricultural sustainability. As the frequency of heavy rainfall has increased globally, waterlogging has become a pressing global issue that has a significant impact on the growth and development of oilseed crops. Due to decreased aerobic respiration in the rhizosphere, various physiological processes, including metabolic reactions, hormone production, and signaling cascades, are adversely impacted by waterlogging. These physiological changes impair reproductive health, resulting in decreased oilseed crop yields. In response to waterlogging, the most common resistance mechanisms developed by crop plants are development of aerenchyma, adventitious roots, and radial oxygen loss barrier. Consequently, the identification and selection of parents with resistance mechanisms, as well as their incorporation into breeding programmes, are essential for sustaining crop production. Thus, a better understanding of the physiological and biochemical mechanisms during waterlogging followed by identification of underlying key regulatory molecules would greatly facilitate the oilseed breeding programs. This review systematically summarizes the response of crop plants to waterlogging through adaptations and the strategies for introduction of waterlogging resistance in oilseed crops. [ABSTRACT FROM AUTHOR]

Black pepper (Piper nigrum) is a spice commonly used in kitchens throughout the world. Black pepper production is devastated by a range of pathogenic agents, including Phytophthora capsici and Meloidogyne incognita. Many efforts have been directed towards finding black pepper cultivars that are resistant to these pathogens. In this work, a 39‐accession germplasm panel of species in the Piper family collected throughout Vietnam was described. Preliminary tests using P. capsici inoculation onto leaves were carried out to identify potentially resistant accessions. Next, candidate plants were inoculated with P. capsici mycelial suspension and survival rates were assessed 15, 30 and 45 days postinoculation. In addition, Piper plants were challenged with M. incognita by adding larvae/juveniles to growing pots. Resistance to M. incognita was determined by the number of root galls and the percentage of plants with yellow leaves 1, 2 and 4 months after treatment. Piper accessions were also subjected to a 4‐day waterlogged treatment. Two accessions (HUIB_PH30 and HUIB_PD36) demonstrated high levels of resistance to all biological and water stresses. Micromorphological characterizations revealed that the amount of intercellular spaces in the root cortex correlated with the resistance to P. capsici and waterlogging tolerance. Hence, the abundance of intercellular spaces can serve as a guide for further selection of black pepper accessions that are resistant to common diseases and tolerant to waterlogged conditions. [ABSTRACT FROM AUTHOR]

Waterlogging significantly impacts plant growth and development by altering nutrient uptake and antioxidant enzyme functions, resulting in reduced yield. Plants need sulfur (S) to produce reduced glutathione (GSH), a thiol compound that combats abiotic stresses. It is hypothesized that supplying S to high S-demanding oilseed rape plants beyond its growth requirements can reduce the adverse effect of waterlogging stress. Therefore, this study evaluated the comparative effect of different S doses (mg kg− 1 soil), i.e., no-S (S0), low-S (S1, 35), medium-S (S2, 70), and high-S (S3, 140) on growth, yield and antioxidant defense systems of normal growing and waterlogged oilseed rape plants. Waterlogging was imposed at the inflorescence emergence stage for 7 days by retaining a 3-cm layer of water above the soil surface. Waterlogged plants supplemented with high-S showed improved growth and higher yield than those supplemented with lower S levels, and this response was associated with improved activity/contents of antioxidants, including ascorbate (AsA), GSH, ascorbate peroxidase, catalase, glutathione reductase, glutathione peroxidase, glutathione S-transferase, monodehydroascorbate reductase, and dehydroascorbate reductase, with concomitant lowering of hydrogen peroxide, dehydroascorbate and malondialdehyde content. Furthermore, leaf S concentration was enhanced in waterlogged plants treated with high-S, while anions were regulated whereby Cl− uptake was decreased. However, under control conditions, high-S did not provide additional benefits of improved plant growth, yield, and antioxidant activities compared to the medium-S application. Thus, it is concluded that additional S supplementation mitigates the adverse effects of waterlogging stress on oilseed rape, and needs to be employed as a potential strategy to alleviate the negative effects of this abiotic stress. [ABSTRACT FROM AUTHOR]

‘Hangju’ is a variety of Chrysanthemum × morifolium Ramat. with both edible and medicinal value, cultivated as a traditional Chinese medicine for four centuries. The cultivation of ‘Hangju’ is currently at risk due to waterlogging, yet there is a lack of comprehensive understanding regarding its response to waterlogging stress. This study compared the waterlogging-tolerant ‘Hangju’ variety Enhanced Waterlogging Tolerance (EWT) with the waterlogging-sensitive variety CK (‘zaoxiaoyangju’). EWT exhibited a more developed aeration tissue structure and demonstrated rapid growth regarding the adventitious roots following waterlogging. The time-course transcriptome analysis indicated that EWT could swiftly adjust the expression of the genes involved in the energy metabolism signaling pathways to acclimate to the waterlogged environment. Through WGCNA analysis, we identified Integrase-Type DNA-Binding Protein (CmTINY2) as a key factor in regulating the waterlogging tolerance in EWT. CmTINY2, a transcription factor belonging to the ethylene-responsive factor (ERF) subfamily III, operated within the nucleus and activated downstream gene expression. Its role in enhancing the waterlogging tolerance might be linked to the control of the stomatal aperture via the Ethylene-Responsive Element (ERE) gene. In summary, our research elucidated that the waterlogging tolerance displayed by EWT is a result of a combination of the morphological structure and molecular regulatory mechanisms. Furthermore, the study of the functions of CmTINY2 from ERF subfamily III also broadened our knowledge of the role of the ERF genes in the waterlogging signaling pathways.

Waterlogging is a growing threat to wheat production in high-rainfall areas. In this study, a doubled haploid (DH) population developed from a cross between Yangmai 16 (waterlogging-tolerant) and Zhongmai 895 (waterlogging-sensitive) was used to map quantitative trait loci (QTL) for waterlogging tolerance using a high-density 660K single-nucleotide polymorphism (SNP) array. Two experimental designs, waterlogging concrete tank (CT) and waterlogging plastic tank (PT), were used to simulate waterlogging during anthesis in five environments across three growing seasons. Waterlogging significantly decreased thousand-kernel weight (TKW) relative to non-waterlogged controls, although the degree varied across lines. Three QTL for waterlogging tolerance were identified on chromosomes 4AL, 5AS, and 7DL in at least two environments. All favorable alleles were contributed by the waterlogging-tolerant parent Yangmai 16. QWTC.caas-4AL exhibited pleiotropic effects on both enhancing waterlogging tolerance and decreasing plant height. Six high-confidence genes were annotated within the QTL interval. The combined effects of QWTC.caas-4AL and QWTC.caas-5AS greatly improved waterlogging tolerance, while the combined effects of all three identified QTL (QWTC.caas-4AL, QWTC.caas-5AS, and QWTC.caas-7DL) exhibited the most significant effect on waterlogging tolerance. Breeder-friendly kompetitive allele-specific PCR (KASP) markers (K_AX_111523809, K_AX_108971224, and K_AX_110553316) flanking the interval of QWTC.caas-4AL, QWTC.caas-5AS, and QWTC.caas-7DL were produced. These markers were tested in a collection of 240 wheat accessions, and three superior polymorphisms of the markers distributed over 67 elite cultivars in the test population, from the Chinese provinces of Jiangsu, Anhui, and Hubei. The three KASP markers could be used for marker-assisted selection (MAS) to improve waterlogging tolerance in wheat.

Plant plasma membrane H+-ATPase is a transport protein that is generally located on the plasma membrane and generates energy by hydrolyzing adenosine triphosphate (ATP) to pump hydrogen ions (H+) in the cytoplasm out of the cell against a concentration gradient. The plasma membrane H+-ATPases in plants are encoded by a multigene family and potentially play a fundamental role in regulating plant responses to various abiotic stresses, thus contributing to plant adaptation under adverse conditions. To understand the characteristics of the plasma membrane H+-ATPase family in peach (Prunus persica), this study analyzed the plasma membrane H+-ATPase family genes in peach. The results showed that there were 27 members of the plasma membrane H+-ATPase family in peach with amino acid sequences ranging from 943 to 1327. Subcellular localization showed that 23 of the 27 members were located on the cell membrane, and the phylogenetic tree analysis indicated that peach plasma membrane H+-ATPase members were divided into five groups. There were four genes with tandem repeat relationships, and six plasma membrane H+-ATPase genes were differentially expressed after 5 days of flooding and under non-flooding conditions based on the RNA-seq and RT-qPCR analyses. This study also investigated the characteristics and possible functions of the plasma membrane H+-ATPase family members in peach. The results provide theoretical support for further studies on their biological functions in peach.

In order to explore the effect of fertilization patterns on the growth of rapeseed seedlings under waterlogging stress, three fertilization patterns (conventional fertilization, supplemental organic fertilization, and supplemental microbial fertilization) were set up using the variety Xiangyou 708 as the material, and waterlogging treatment was carried out during the seedling stage of rapeseed. The effects of fertilization patterns on the growth of rapeseed seedlings and rhizosphere microorganisms under waterlogging stress were investigated. The results showed that all three fertilization patterns exhibited that waterlogging stress inhibited the growth of rapeseed seedlings, inhibited root activity, and changed the structure of rhizosphere bacterial community structure. However, supplemental organic and microbial fertilization better promoted the growth of rapeseed seedlings, reduced the impact of waterlogging stress on the growth of rapeseed seedlings, and accelerated the recovery of rapeseed seedlings after waterlogging stress. Under normal water supply, supplemental organic fertilization enriched P_Bacteroidota, P_Actinobacteriota, P_Chloroflexi, and G_Flavisolibacter in the rhizosphere soil of rapeseed, while supplemental microbial fertilization enriched P_Bacteroidota and G_Flavisolibacter in the rhizosphere soil of rapeseed. After 7 days of waterlogging treatment, supplemental organic fertilization enriched P_Verrucomicrobiota in the rhizosphere soil of rapeseed, while supplemental microbial fertilization enriched P_Actinobacteriota, G_SC-I-84, and G_Ellin6067 in the rhizosphere soil of rapeseed. The enrichment of these bacteria may be related to the growth promotion and waterlogging tolerance of rapeseed. This study provides evidence that microbial and organic fertilizer can promote the growth of rapeseed and enhance its waterlogging tolerance, as well as evidence that some rhizosphere microorganisms have a potential role in promoting the growth and waterlogging tolerance of rapeseed.

• Moringa oleifera Lam. is a valuable vegetable with considerable health benefits. • 76 self-pollinated lines from a waterlogging-tolerant parent were characterised. • Three self-pollinated lines are tolerant to waterlogged conditions. • High level of genetic diversity demonstrated by RAPD and SRAP marker analyses. • Large variations in phenolic and flavonoid contents among self-pollinated lines. Moringa oleifera Lam. (drumstick) is a valuable vegetable with considerable health benefits. The cultivation of M. oleifera is limited to well-drained soil as they are poorly tolerant to waterlogged conditions. In this study, self-pollinated lines, derived from a parental drumstick exhibiting high tolerance to waterlogging in Hue city, Vietnam, were studied. Seventy six lines were assayed for their morphological traits and waterlogging tolerance. Furthermore, seven RAPD primers and three SRAP primer pairs were employed to explore the genetic diversity among the M. oleifera parental and 76 self-pollinated lines. A high level of genetic diversity was observed within the germplasm. The dendrogram divided the germplasm genetically into five main groups. Finally, their phenolic and flavonoid contents were determined to identify lines with the highest concentration of bioactive compounds. These findings can aid future breeding programs to create elite cultivars of Moringa oleifera. [ABSTRACT FROM AUTHOR]

Waterlogging stress is one of the major abiotic stresses that negatively affect chrysanthemum (Chrysanthemum morifolium Ramat.) growth and development, thus reducing its productivity. Therefore, there is a need to develop waterlogging-tolerant chrysanthemum germplasms to deal with this problem, and the identification of tolerant wild chrysanthemum (C. indicum) is relevant to the improvement of cultivated chrysanthemum targeting resistance traits. In the current study, we aimed to evaluate the waterlogging tolerance of wild chrysanthemums by using the membership function value of waterlogging (MFVW) and multiple regression analysis based on seven morphological traits related to waterlogging tolerance. By MFVW, the investigated 19 C. indicum accessions were classified into five grades: one waterlogging-tolerant accession, 12 moderately waterlogging-tolerant accessions, and every two accessions for highly waterlogging-tolerant, waterlogging-sensitive, and highly waterlogging-sensitive types, respectively. Of all traits tested, Score, shoot fresh weight, and root fresh weight are considered reliable indicators, exhibiting a higher correlation with waterlogging tolerance. The mathematical evaluation model of waterlogging tolerance based on MFVW proved robust by comparing the observed MFVW and predicted Y values in two interspecific segregating F1 populations derived from C. indicum and C. japonense, with average R2 ranging between 0.957 and 0.982. The method established in the current study provides a reference for the rapid identification and accurate prediction of waterlogging tolerance in chrysanthemum germplasms, and the highly waterlogging-tolerant wild chrysanthemum germplasms identified herein help widen the genetic base for breeding chrysanthemum cultivars with desirable waterlogging tolerance. [ABSTRACT FROM AUTHOR]

Waterlogging‐sensitive ('ZHC1') and waterlogging‐tolerant ('ZHC2') hot peppers were selected from three years of field investigation. 'ZHC2' could keep growing under waterlogging conditions, its lateral roots were distributed near the water surface, and its stem base grew many adventitious roots and rapidly formed aerenchyma. The chlorophyll content was stable, and the contents of carotenoid and amino acid were significantly greater in 'ZHC2' than in 'ZHC1' under both waterlogging stress and recovery conditions. However, waterlogging stress led to in‐root decay and a significant increase in malondialdehyde content of 'ZHC1'. Using transcriptome analysis, we correlated the functions of many waterlogging‐responsive differentially expressed genes closely with the pathways for reactive oxygen species production, lutein synthesis, auxin signal transduction, and amino acid synthesis, which were consistent with the above growth and physiological data (adventitious root formation and the contents of malondialdehyde, carotenoids and amino acids). Some novel candidate genes related to waterlogging tolerance were also detected. This work provides new insights into waterlogging‐tolerant mechanisms and valuable clues for breeding of waterlogging‐tolerant peppers. [ABSTRACT FROM AUTHOR]

Waterlogging causes various metabolic, physiological, and morphological changes in crops, resulting in yield loss of most legumes in rainfed and irrigated agriculture. However, research on cowpea genotypes using physiological and biochemical traits as a measure of tolerance to waterlogging stress is limited. We evaluated the impacts of 7 days of waterlogging (DOW) and 7 days of recovery (DOR) on the physiology and biochemistry of two cowpea (Vigna unguiculata (L.) Walp) genotypes (UCR 369 and EpicSelect.4) with contrasting waterlogging tolerance. Cowpea genotypes were grown in a controlled environment until the R2 stage and then subjected to 7 DOW. Later, the waterlogged plants were reoxygenated for an additional 7 DOR. Overall, cowpea genotypes had a contrasting response to waterlogging using different mechanisms. Compared to the control, the photosynthetic parameters of both cowpea genotypes were impaired under 7 DOW and could not recover at 7 DOR, with a larger decline in EpicSelect.4.7 DOW caused significant loss in the chlorophyll and carotenoid content of both genotypes. However, only waterlogged UCR 369 was not photo-inhibited and able to restore the levels of chlorophyll and carotenoids at 7 DOR. In addition, 7 DOW induced intense stress in UCR 369 with increased zeaxanthin, sucrose, and flavonoid content, while these metabolites were decreased in EpicSelect.4. On the other hand, glucose, fructose, and phenolic content were increased in EpicSelect.4 but decreased in UCR 369 at 7 DOR. In summary, compared to EpicSelect.4, UCR 369 restored their photosynthetic pigments and metabolites to the control levels at 7 DOR, indicating a likely tolerance to waterlogging stress. • Cowpea genotypes respond to waterlogging using contrasting mechanisms. • Cowpea genotypes that accumulate more zeaxanthin, sucrose, and flavonoids during waterlogging show greater tolerance. • UCR 369 restored the studied physiological and biochemical parameters to their control levels after recovery. • Downregulation of carbon assimilation in EpicSelect.4 was driven by both stomatal and non-stomatal factors. [ABSTRACT FROM AUTHOR]

A set of diverse soybean genotypes were evaluated to identify contrasting phenotypes for understanding the genetics of waterlogging and response to the selection of primary and discernable traits for pregermination anaerobic stress tolerance. Agro‐morphological characterization of genotypes was also carried out. Screening and tolerance to waterlogging were based on the ability of genotypes to germinate in excessive stress duration in days. The existence of significant variability in genotypes of soybean suggested the use of systematic selection for improving pregermination anaerobic stress tolerance. The study revealed that waterlogging tolerance was governed by testa colour of genotypes. Our results indicated a significant (P < 0.05) correlation with seed weight, flower, hypocotyl and testa colour under pregermination anaerobic stress. In conclusion, the study points out that testa integrity and delay in germination are required to be used as one of the criteria for indirect selection in breeding for pregermination waterlogging tolerance. [ABSTRACT FROM AUTHOR]

Waterlogging is an important environmental stress limiting the productivity of crops worldwide. Cowpea (Vigna unguiculata L.) is particularly sensitive to waterlogging stress during the reproductive stage, with a consequent decline in pod formation and yield. However, little is known about the critical processes underlying cowpea's responses to waterlogging during the reproductive stage. Thus, we investigated the key parameters influencing carbon fixation, including stomatal conductance (gs), intercellular CO2 concentration, chlorophyll content, and chlorophyll fluorescence, of two cowpea genotypes with contrasting waterlogging tolerance. These closely related genotypes have starkly contrasting responses to waterlogging during and after 7 days of waterlogging stress (DOW). In the intolerant genotype ('EpicSelect.4'), waterlogging resulted in a gradual loss of pigment and decreased photosynthetic capacity as a consequent decline in shoot biomass. On the other hand, the waterlogging-tolerant genotype ('UCR 369') maintained CO2 assimilation rate (A), stomatal conductance (gs), biomass, and chlorophyll content until 5 DOW. Moreover, there was a highly specific downregulation of the mesophyll conductance (gm), maximum rate of Rubisco (Vcmax), and photosynthetic electron transport rate (Jmax) as non-stomatal limiting factors decreasing A in EpicSelect.4. Exposure of EpicSelect.4 to 2 DOW resulted in the loss of PSII photochemistry by downregulating the PSII quantum yield (Fv/Fm), photochemical efficiency (ΦPSII), and photochemical quenching (qP). In contrast, we found no substantial change in the photosynthesis and chlorophyll fluorescence of UCR 369 in the first 5 DOW. Instead, UCR 369 maintained biomass accumulation, chlorophyll content, and Rubisco activity, enabling the genotype to maintain nutrient absorption and photosynthesis during the early period of waterlogging. However, compared to the control, both cowpea genotypes could not fully recover their photosynthetic capacity after 7 DOW, with a more significant decline in EpicSelect.4. Overall, our findings suggest that the tolerant UCR 369 genotype maintains higher photosynthesis under waterlogging stress attributable to higher photochemical efficiency, Rubisco activity, and less stomatal restriction. After recovery, the incomplete recovery of A can be attributed to the reduced gs caused by severe waterlogging damage in both genotypes. Thus, promoting the rapid recovery of stomata from waterlogging stress may be crucial for the complete restoration of carbon fixation in cowpeas during the reproductive stage. [ABSTRACT FROM AUTHOR]

Kiwifruit is commonly sensitive to waterlogging stress, and grafting onto a waterlogging-tolerant rootstock is an efficient strategy for enhancing the waterlogging tolerance of kiwifruit plants. KR5 (Actinidia valvata) is more tolerant to waterlogging than 'Hayward' (A. deliciosa) and is a potential resistant rootstock for kiwifruit production. Here, we focused on evaluating the performance of the waterlogging-sensitive kiwifruit scion cultivar 'Zhongmi 2′ when grafted onto KR5 (referred to as ZM2/KR5) and Hayward (referred to as ZM2/HWD) rootstocks, respectively, under waterlogging stress. The results showed 'Zhongmi 2′ performed much better when grafted onto KR5 than when grafted onto 'Hayward', exhibiting higher photosynthetic efficiency and reduced reactive oxygen species (ROS) damage. Furthermore, the roots of ZM2/KR5 plants showed greater root activity and energy supply, lower ROS damage, and more stable osmotic adjustment ability than the roots of ZM2/HWD plants under waterlogging stress. In addition, we detected the expression of six key genes involved in the kiwifruit waterlogging response mechanism, and these genes were remarkably induced in the ZM2/KR5 roots but not in the ZM2/HWD roots under waterlogging stress. Moreover, principal component analysis (PCA) further demonstrated the differences in the physiological responses of the ZM2/KR5 and ZM2/HWD plants under waterlogging stress. These results demonstrated that the KR5 rootstock can improve the waterlogging tolerance of grafted kiwi plants by regulating physiological and biochemical metabolism and molecular responses. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA) is an endogenous growth regulator. It is vital for the growth and development, photosynthesis, disease resistance, and abiotic stress tolerance of plants. This study aimed to investigate the effects of exogenous SA on photosynthetic characteristics and antioxidant system in the four-leaf-stage waxy corn inbred seedlings SY-MY13 (waterlogging-resistant) and SY-XT1 (waterlogging-sensitive) under waterlogging stress. Waterlogging stress negatively influenced the morphology, plant height, biomass, photosynthetic characteristics, and chlorophyll content of waxy corn seedlings, obstructing their growth and development. SY-MY13 exhibited better growth and photosynthesis than SY-XT1 under waterlogging, this was due to SY-MY13 possessed excellent scavenging ability to reactive oxygen species (ROS). However, the application of exogenous SA could not only reduce the accumulation of ROS and regulate the activities of antioxidant enzymes but also improve photosynthesis in leaves and promote the growth of seedlings. Hence, the results revealed that the potential of SA as a promising exogenous growth regulator mediated physiological and photosynthetic adaptation of waxy corn seedlings under waterlogging stress, which might prove helpful for other plants suffering from waterlogging stress.

Key message: The transcription of GhAG2 was strongly enhanced by glyphosate treatment. Overexpression of GhAG2 could improve plant tolerance to salt and salicylic acid stress. Although glyphosate has been widely used as an herbicide over the past decade owing to its high efficacy on weed controls and worldwide commercialization of glyphosate-resistant crops, little is known about the glyphosate-induced responses and transcriptional changes in cotton plants. Here, we report the identification of 26 differentially expressed genes after glyphosate treatment, among which, six highly up-regulated sequences share homology to cotton expressed sequence tags (ESTs) responsive to abiotic stresses. In addition, we cloned GhAG2, a gene whose transcription was strongly enhanced by glyphosate treatment and other abiotic stresses. Transgenic GhAG2 plants showed improved tolerance to salt, and salicylic acid (SA) stress. The results could open the door to exploring the function of the GhAG2 proteins, the glyphosate-induced transcriptional profiles, and the physiological biochemical responses in cotton and other crops. GhAG2 could also be used to improve salt stress tolerance through breeding and biotechnology in crops. Furthermore, these results could provide guidelines to develop a glyphosate-inducible system for controlled expression of targeted genes in plants. [ABSTRACT FROM AUTHOR]

Crop wild relatives are species related to cultivated plants, whose populations have evolved in natural conditions and confer them valuable adaptive genetic diversity, that can be used in introgression breeding programs. Targeting four wild lentil taxa in Europe, we applied the predictive characterization approach through the filtering method to identify populations potentially tolerant to drought, salinity, and waterlogging. In parallel, the calibration method was applied to select wild populations potentially resistant to lentil rust and broomrape, using, respectively, 351 and 204 accessions evaluated for these diseases. An ecogeographic land characterization map was used to incorporate potential genetic diversity of adaptive value. We identified 13, 1, 21, and 30 populations potentially tolerant to drought, soil salinity, waterlogging, or resistance to rust, respectively. The models targeting broomrape resistance did not adjust well and thus, we were not able to select any population regarding this trait. The systematic use of predictive characterization techniques may boost the efficiency of introgression breeding programs by increasing the chances of collecting the most appropriate populations for the desired traits. However, these populations must still be experimentally tested to confirm the predictions. [ABSTRACT FROM AUTHOR]

Crop wild relatives are species related to cultivated plants, whose populations have evolved in natural conditions and confer them valuable adaptive genetic diversity, that can be used in introgression breeding programs. Targeting four wild lentil taxa in Europe, we applied the predictive characterization approach through the filtering method to identify populations potentially tolerant to drought, salinity, and waterlogging. In parallel, the calibration method was applied to select wild populations potentially resistant to lentil rust and broomrape, using, respectively, 351 and 204 accessions evaluated for these diseases. An ecogeographic land characterization map was used to incorporate potential genetic diversity of adaptive value. We identified 13, 1, 21, and 30 populations potentially tolerant to drought, soil salinity, waterlogging, or resistance to rust, respectively. The models targeting broomrape resistance did not adjust well and thus, we were not able to select any population regarding this trait. The systematic use of predictive characterization techniques may boost the efficiency of introgression breeding programs by increasing the chances of collecting the most appropriate populations for the desired traits. However, these populations must still be experimentally tested to confirm the predictions.

Unfavorable weather in the Philippines leaves the sugarcane industry vulnerable to losses from flooded fields. A system of identification should be developed to supplement the country’s lack of sugarcane varieties tolerant to waterlogging. This study investigated the effect of waterlogging imposed during the early stalk elongation stage on sugarcane grown in contrasting soil types. In 2017–2018, two split-plot trials at the Institute of Plant Biology (IPB) University of the Philippines (UP) Los Baños experimental area and UP La Granja (La Carlota City, Negros Occidental) evaluated the response of 10 high yielding varieties (HYVs) to flooding for 2 wk during stalk elongation stage [6 mo after planting (MAP)]. Waterlogged sugarcane varieties showed a location-dependent response in terms of projected ton cane per hectare (Tc ha–1) and sugar yield in 50-kg bags per hectare (Lkg ha–1). Waterlogging in the UP La Granja trial affected cane and sugar yield with Phil 2000-2569, Phil 2000-1419, Phil 2000-2155, and Phil 2003-1389 losing 22.3–35.8% in cane tonnage. The IPB trial showed no significant effect of waterlogging, primarily due to continuous reflooding. Geometric mean productivity (GMP) and stress tolerance index (STI) values confirm varietal productivity is location-dependent. Phil 2000-1419 and Phil 2000-2569 have the highest GMP and STI for the IPB trial and UP La Granja trial, respectively. GMP and STI models provide aid in selection for waterlogging tolerance. [ABSTRACT FROM AUTHOR]

In lowland rice ecosystems stagnant flooding or partial submergence has a significant negative impact on important yield attributing traits resulting in substantial grain yield reduction. Genetics of this stress is not yet studied intensively. Rashpanjor (IC 575321), a landrace from India, was identified and used as the tolerant donor for stagnant flooding and was crossed with high yielding variety Swarna to develop the RIL population for the present investigation. Yield and yield attributing traits of 180 F2:8 lines in rainfed non-stressed and stressed (stagnant flooding with 45 ± 5 cm standing water) conditions were recorded in the wet season of 2018 and stress susceptibility and tolerance indices of yield component traits were deduced. Homo-polymorphic high-quality SNPs between two parents derived from genotyping by sequencing were employed and 17 putative QTLs for plant height, shoot elongation, panicle number, grain weight, panicle length in control and stagnant flooding conditions were identified. Tolerance and susceptibility indexes for these traits were detected in chromosomes 1, 3, 4, 5, 6, 10, 11, and 12 with PVE ranging from 6.53 to 57.89%. Two major QTLs clusters were found for stress susceptibility index of grain and panicle weight on chromosome 1 and plant height in non-stress condition and stress tolerance index of elongation ability on chromosome 3. Putative functional genes present either in associated non-synonymous SNPs or inside the QTL regions were also predicted. Some of them were directly associated with ethylene biosynthesis and encoding auxin responsive factors for better adaptation under stagnant flooding and also coded for different transcription factors viz. NAC domain-binding protein, WRKY gene family, and MYB class known for ROS scavenging and production of metabolites to enhance tolerance to stagnant flooding. [ABSTRACT FROM AUTHOR]

Soil waterlogging is a major environmental stress that suppresses the growth and productivity of rapeseed (Brassica napus L.). Natural genetic variations in waterlogging tolerance (WT) were observed but no QTL mapping has been done for WT related traits in rapeseed. In this study, QTL associated with three WT related traits including relative root length (RRL), relative hypocotyl length (RHL) and relative fresh weight (RFW) were dissected using a set of reciprocal introgression lines (ILs) derived from the cross GH01×ZS9, which showed significant difference in WT. Genotyping-by-sequencing (GBS) of the populations were performed, totally 1 468 and 1 450 binned SNPs were identified for GIL (GH01 as the recurrent parent) and ZIL (ZS9 as the recurrent parent) population, respectively. A total of 66 distinct QTLs for WT at the seedling establishment stage including 31 for RRL, 17 for RHL and 18 for RFW were detected. Among the 66 QTLs, 20 (29.4%) QTLs were detected in both genetic backgrounds and then they were integrated into six QTL clusters, which can be targeted in rapeseed breeding for improvement of WT through marker-assisted selection (MAS). Based on the physical positions of SNPs and the functional annotation of the Arabidopsis thaliana genome, 56 genes within the six QTL cluster regions were selected as preliminary candidate genes, then the resequencing and transcriptome information about parents were applied to narrow the extent of candidate genes. Twelve genes were determined as candidates for the six QTL clusters, some of them involved in RNA/protein degradation, most of them involved in oxidation-reduction process. These findings provided genetic resources, candidate genes to address the urgent demand of improving WT in rapeseed breeding.

Waterlogging is a major constraint of mungbean production in the tropical and subtropical regions of the world and can cause a significant yield loss. The study evaluated 100 mungbean genotypes for tolerance to waterlogging employing rigorous field screening procedures. Three-week-old seedlings of 100 mungbean genotypes were subjected to waterlogging for 3 days maintaining a waterlogging depth of 2.5 cm. Waterlogging tolerance was evaluated during the periods of recovery and final harvest considering relative performance (values of waterlogging relative to non-waterlogging controls) of 18 plant traits. All the genotypes showed a wide range of variation in relative values. Some genotypes subjected to waterlogging produced plenty of adventitious roots that contributed to foliage development and chlorophyll increment, which resulted in better shoot growth, and eventually yield of mungbean increased. Nine plant traits highly associated in waterlogged conditions were used in cluster analysis. The genotypes within cluster 6 and cluster 7 performed better regarding almost all plant traits whereas cluster 4 performed very poorly. Discriminant function analysis showed that function 1 and function 2 explained 54.5% and 32.2%, respectively and altogether 86.7% variation in the genotypes. The harvest index and straw dry matter mostly explained the total variance in function 1. Dry matter of root, shoot and straw explained the maximum variance in function 2. Root dry matter played the most dominant role in explaining the maximum variance in the genotypes. The genotypes IPSA-10 and VC 6379 (23-11) showed a better degree of tolerance to waterlogging concerning yield and associated morpho-physiological traits.

Fifteen peanut varieties at the pod filling stage were exposed to waterlogging stress for 7 days, the enzyme activities and fluorescence parameters were measured after 7 days of waterlogging and drainage. The waterlogging tolerance and recovery capability of varieties were identified. After waterlogging, waterlogging tolerance coefficient (WTC) of relative electrolyte linkage (REL), malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, and catalase (CAT) activity, non-photochemical quenching (NPQ) and photochemical quenching (qL) of leaves of most peanut varieties were increased, while the WTC of the soil and plant analysis development (SPAD) value, PS II actual quantum yield (ΦPS II), maximum photochemical efficiency (Fv/Fm) were decreased. After drainage, the WTC of REL, MDA content, SOD and CAT activity of leaves were decreased compared with that of after waterlogging, but these indicators of a few cultivars were increased. ΦPS II, Fv/Fm and qL can be used as important indexes to identify waterlogging recovery capability. There was a significant negative correlation between recovery capability and the proportion of reduction in yield, while no significant correlation was found between waterlogging tolerance and the proportion of reduction in yield. Therefore, it is recommended to select varieties with high recovery capability and less pod number reduction under waterlogging in peanut breeding and cultivation.

Climate fluctuations and their effect in food production, its quality and disruption of food availability are well apparent. Temperature and moisture extremes, unseasonal rainfall, droughts, floods, cloud bursts, cyclonic storms, etc. are becoming more frequent and consequently, the impacts of climate volatility on severity and alteration of biotic and abiotic stresses, have emerged as serious challenges for the scientific community. Climate-driven changing rainfall pattern has built up waterlogging (WL) stress as one of the major limiting factors in maize productivity in tropical and subtropical regions. Maize is susceptible to waterlogging stress especially during germination and at the flowering stage when excessive rains lead to pollen wash and hamper seed set. The review looks back at the different breeding strategies coupled with generated molecular markers information to develop WL tolerant cultivars for productivity enhancement in tropical maize. [ABSTRACT FROM AUTHOR]

Waterlogging has increasingly become one of the major constraints to maize (Zea mays L.) production in some maize growing areas as it seriously decreases the yield. Waterlogging tolerance in maize germplasm provides a basis for maize waterlogging improvement. In this study, nine seedling traits, plant height (PH), root length (RL), shoot dry weight (SDW), root dry weight (RDW), adventitious root number (ARN), node number of brace root (BRNN), brace root number (BRN), brace root dry weigh (BRDW), survival rate (SR), and the secondary traits that were defined as relative phenotypic value of seedling traits under waterlogging and control treatments were used in a natural population that contain 365 inbred lines to evaluate the waterlogging tolerance of tropical maize. The result showed that maize waterlogging tolerance was genetically controlled and seedling traits were significantly different between the control and waterlogging treatments. PH, RL, SDW, and RDW are important seedling traits for waterlogging tolerance identification. Some tropical maize inbred lines were identified with extreme waterlogging tolerance that can provide an important germplasm resource for breeding. Population structure analysis showed that two major phylogenetic subgroups in tropical maize could be identified. Genome-wide association study (GWAS) using 39,266 single nucleotide polymorphisms (SNPs) across the whole genome identified 49 trait-SNPs distributed on over all 10 chromosomes excluding chromosome 10. Seventy-one significant SNPs, distributed on all 10 chromosomes excluding chromosome 5, were identified by extend bulked sample analysis (Ext-BSA) based on the inbred lines with extreme phenotypes. GWAS and Ext-BSA identified the same loci on bin1.07, bin6.01, bin2.09, bin6.04, bin7.02, and bin7.03. Nine genes were proposed as potential candidate genes. Cloning and functional validation of these genes would be helpful for understanding the molecular mechanism of waterlogging tolerance in maize. [ABSTRACT FROM AUTHOR]

To provide references for poplar cultivation in waterlogged prone area of Jianghan Plain of China, the waterlogging tolerance of 15 poplar clones widely cultivated in these areas were evaluated based on their responses to 45-day waterlogging stress followed by 15-day drainage recovery in morphology, growth, biomass accumulation, leaf gas exchange and chlorophyll fluorescence parameters. The results showed that the normal watered seedlings (CK) of the 15 clones grew vigorously during the experiment, and no defoliation and death occurred. For the seedlings under waterlogging treatment (water 10 cm above the soil surface), its morphology changed markedly, including slowing growth, chlorosis and abscission of leaves, development of hypertrophied lenticels and adventitious roots etc. Waterlogging stress significantly inhibited the seedling growth of height and ground diameter, biomass accumulation, as well as leaf gas exchange and chlorophyll fluorescence parameters of the 15 clones with varying degrees. The net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), intercellular CO2 concentration/ environmental CO2 concentration (Ci/Ca), variable fluorescence (Fv), variable fluorescence/ initial fluorescence (Fv/Fo) and PS Ⅱ primary light energy conversion efficiency (Fv/Fm) decreased gradually with the prolonged waterlogging, and reached their bottom on day 45. During the terminal recovery stage, the leaf gas exchange and chlorophyll fluorescence parameters of the most clones increased, but their recovery abilities were significantly different. At the end of the experiment, the highest survival rates (100%) were observed in DHY, HS-1, HS-2, I-72, I-69, I-63 and NL-895, and the lowest (zero) occurred in XYY. Survival rates of the other clones ranged from 33.33% to 83.33%. Both results of cluster analysis and membership function analysis showed that HS-1, I-69, DHY, NL-895 and HS-2 had the strongest waterlogging tolerance, XYY and HBY were the worst, and the other clones were moderate. These results would provide guidance not only for the selection of cultivated varieties in Jianghan Plain, but also for the selection of hybrid parents for waterlogging resistance breeding.

Waterlogging is one of the main abiotic stresses severely reducing barley grain yield. Barley breeding programs focusing on waterlogging tolerance require an understanding of genetic loci and alleles in the current germplasm. In this study, 247 worldwide spring barley genotypes grown under controlled field conditions were genotyped with 35,926 SNPs with minor allele frequency (MAF) > 0.05. Significant phenotypic variation in each trait, including biomass, spikes per plant, grains per plant, kernel weight per plant, plant height and chlorophyll content, was observed. A genome-wide association study (GWAS) based on linkage disequilibrium (LD) for waterlogging tolerance was conducted. Population structure analysis divided the population into three subgroups. A mixed linkage model using both population structure and kinship matrix (Q+K) was performed. We identified 17 genomic regions containing 51 significant waterlogging-tolerance-associated markers for waterlogging tolerance response, accounting for 5.8–11.5% of the phenotypic variation, with a majority of them localized on chromosomes 1H, 2H, 4H, and 5H. Six novel QTL were identified and eight potential candidate genes mediating responses to abiotic stresses were located at QTL associated with waterlogging tolerance. To our awareness, this is the first GWAS for waterlogging tolerance in a worldwide barley collection under controlled field conditions. The marker-trait associations could be used in the marker-assisted selection of waterlogging tolerance and will facilitate barley breeding.

Waterlogging is one of the main abiotic stresses severely reducing barley grain yield. Barley breeding programs focusing on waterlogging tolerance require an understanding of genetic loci and alleles in the current germplasm. In this study, 247 worldwide spring barley genotypes grown under controlled field conditions were genotyped with 35,926 SNPs with minor allele frequency (MAF) > 0.05. Significant phenotypic variation in each trait, including biomass, spikes per plant, grains per plant, kernel weight per plant, plant height and chlorophyll content, was observed. A genome-wide association study (GWAS) based on linkage disequilibrium (LD) for waterlogging tolerance was conducted. Population structure analysis divided the population into three subgroups. A mixed linkage model using both population structure and kinship matrix (Q+K) was performed. We identified 17 genomic regions containing 51 significant waterlogging-tolerance-associated markers for waterlogging tolerance response, accounting for 5.8–11.5% of the phenotypic variation, with a majority of them localized on chromosomes 1H, 2H, 4H, and 5H. Six novel QTL were identified and eight potential candidate genes mediating responses to abiotic stresses were located at QTL associated with waterlogging tolerance. To our awareness, this is the first GWAS for waterlogging tolerance in a worldwide barley collection under controlled field conditions. The marker-trait associations could be used in the marker-assisted selection of waterlogging tolerance and will facilitate barley breeding. [ABSTRACT FROM AUTHOR]

Waterlogging is an environmental stress condition that drastically affects maize growth and development. Plant breeders utilize genetic markers such as single nucleotide polymorphism (SNP) markers to incorporate traits like waterlogging tolerance to stress susceptible crops. This study aimed to validate the SNP markers observed previously from improved waterlogging tolerant maize varieties. To assess waterlogging tolerance among 214 maize lines, secondary traits [chlorophyll, number of adventitious roots (ADVR), days to silking (DS), days to anthesis (DA), anthesis-silking interval (ASI), and number of ears (NEARS)] were measured from plants grown in pots. Only 55 high-performing lines from the potted trial were used in the field trial. Twelve (12) maize lines consistently clustered together with the IPB Var 13, a high-yielding variety even under waterlogging. The study revealed that two putative SNPs from quantitative trait loci (QTLs) involved in waterlogging tolerance overlapped with flavonoid 3'-monooxygenase gene (CYP75B1) and very-long-chain (3R)-3-hydroxyacyl-CoA dehydratase gene (PAS2). These putative candidate SNPs were predicted to activate the deleterious missense variant (PZE09123105094) and splice donor variant (PZE0814653797), respectively. CYP75B1 and PAS2 variants were expected to affect the normal development of stressed young maize due to low antioxidant property, leading to hampered cell differentiation. Waterlogging-tolerant maize lines used in this study were heterozygous for both CYP75B1 and PAS2. Expression analysis and functional studies of CYP75B1 and PAS2 proteins are recommended to assess their abundance and actual role in waterlogging tolerance in maize. The results of this study may contribute to the development of Philippine maize varieties that are tolerant to waterlogging stress and further improve their yield capacity. [ABSTRACT FROM AUTHOR]

The ABI3/VP1 proteins are critical in regulating plant growth and resisting stress. This study successfully cloned ABI3/VP1 from waterlogging tolerant pepper (Capsicum annuum) 'ZHC2'. This gene contains a 1017-bp open reading frame, encoding 338 amino acids, and is most closely related to the protein C. annuum XP 016577237.2. CaABI3/VP1–1 was located in the nucleus. This gene was successfully independently transformed into hot peppers 'ZHC1' and 'DFZJ', as well as Nicotiana benthamiana. CaABI3/VP1 overexpression in hot peppers 'ZHC1' and 'DFZJ', as well as N. benthamiana promoted the growth of lateral roots, adventitious roots, and stems, as well as the lodging-resistant ability. In addition, the degree of leaf wilting was lower than that of wild-type plants. In general, the water, soluble protein, and proline contents, stomatal density, and catalase activity increased, but H 2 O 2 and malondialdehyde levels decreased. The transcriptomic analysis of the 'DFZJ' overexpression line revealed that the "ribosome", "MAPK signaling pathway-plant", "plant hormone signal transduction", "plant-pathogen interaction", "arginine and proline metabolism", and "peroxisome" pathways were enriched. LOC107844566 , LOC107843480 , LOC107879909 , LOC107851756 , LOC107843452 , and LOC107851705 are downstream genes that may be regulated by CaABI3/VP1–1. The physiological and biochemical data were consistent with the transcriptome results. Therefore, CaABI3/VP1–1 should be involved in the waterlogging tolerance of peppers, which would assist in their waterlogging-tolerant breeding. • The ABI3/VP1 gene associated to waterlogging tolerance was cloned from hot pepper. • This gene was successfully transformed into hot peppers and Nicotiana benthamiana. • This gene can increase waterlogging tolerance of peppers and N. benthamiana. • The transcriptomic analysis of revealed that the key pathways and downstream genes regulated by CaABI3/VP1–1. [ABSTRACT FROM AUTHOR]

Abstract Background Waterlogging is one of the main abiotic stresses that limit wheat production. Quantitative proteomics analysis has been applied in the study of crop abiotic stress as an effective way in recent years (e.g. salt stress, drought stress, heat stress and waterlogging stress). However, only a few proteins related to primary metabolism and signal transduction, such as UDP - glucose dehydrogenase, UGP, beta glucosidases, were reported to response to waterlogging stress in wheat. The differentially expressed proteins between genotypes of wheat in response to waterlogging are less-defined. In this study, two wheat genotypes, one is sensitive to waterlogging stress (Seri M82, named as S) and the other is tolerant to waterlogging (CIGM90.863, named as T), were compared in seedling roots under hypoxia conditions to evaluate the different responses at proteomic level. Results A total of 4560 proteins were identified and the number of differentially expressed proteins (DEPs) were 361, 640, 788 in S and 33, 207, 279 in T in 1, 2, 3 days, respectively. These DEPs included 270 common proteins, 681 S-specific and 50 T-specific proteins, most of which were misc., protein processing, DNA and RNA processing, amino acid metabolism and stress related proteins induced by hypoxia. Some specific proteins related to waterlogging stress, including acid phosphatase, oxidant protective enzyme, S-adenosylmethionine synthetase 1, were significantly different between S and T. A total of 20 representative genes encoding DEPs, including 7 shared DEPs and 13 cultivar-specific DEPs, were selected for further RT-qPCR analysis. Fourteen genes showed consistent dynamic expression patterns at mRNA and protein levels. Conclusions Proteins involved in primary metabolisms and protein processing were inclined to be affected under hypoxia stress. The negative effects were more severe in the sensitive genotype. The expression patterns of some specific proteins, such as alcohol dehydrogenases and S-adenosylmethionine synthetase 1, could be applied as indexes for improving the waterlogging tolerance in wheat. Some specific proteins identified in this study will facilitate the subsequent protein function validation and biomarker development.

Kiwifruit is commonly sensitive to waterlogging stress, and grafting onto a waterlogging-tolerant rootstock is an efficient strategy for enhancing the waterlogging tolerance of kiwifruit plants. KR5 (Actinidia valvata) is more tolerant to waterlogging than ‘Hayward’ (A. deliciosa) and is a potential resistant rootstock for kiwifruit production. Here, we focused on evaluating the performance of the waterlogging-sensitive kiwifruit scion cultivar ‘Zhongmi 2′ when grafted onto KR5 (referred to as ZM2/KR5) and Hayward (referred to as ZM2/HWD) rootstocks, respectively, under waterlogging stress. The results showed ‘Zhongmi 2′ performed much better when grafted onto KR5 than when grafted onto ‘Hayward’, exhibiting higher photosynthetic efficiency and reduced reactive oxygen species (ROS) damage. Furthermore, the roots of ZM2/KR5 plants showed greater root activity and energy supply, lower ROS damage, and more stable osmotic adjustment ability than the roots of ZM2/HWD plants under waterlogging stress. In addition, we detected the expression of six key genes involved in the kiwifruit waterlogging response mechanism, and these genes were remarkably induced in the ZM2/KR5 roots but not in the ZM2/HWD roots under waterlogging stress. Moreover, principal component analysis (PCA) further demonstrated the differences in the physiological responses of the ZM2/KR5 and ZM2/HWD plants under waterlogging stress. These results demonstrated that the KR5 rootstock can improve the waterlogging tolerance of grafted kiwi plants by regulating physiological and biochemical metabolism and molecular responses.

Ascorbate peroxidase (APX) is a member of the family of heme-containing peroxidases having a similar structure with Cytochrome c peroxidase (CCP) that effectively scavenge cytosolic and chloroplastic hydrogen peroxide (H2O2) under various stresses. In this study, computational characterization and homology analysis of APX protein from waterlogging tolerant (ICPL 84023) and sensitive (ICP 7035) pigeon pea genotypes were carried out resulting in 100% homology with Glycine max in case of former and 99% in later genotypes respectively with 97.39% alignment coverage among each other. The model structure was further refined by various tools like PROCHECK, ProSA, and Verify3D. The planned model of the APX enzyme was then tested to dock with H2O2along with molecular dynamics (MD) simulation analysis. The docked complex of ICPL 84023 showed the best G-score (23.39 kcal/mol) in comparison to ICP 7035 (16.74 kcal/mol) depicting the higher production of APX for scavenging reactive oxygen species (ROS) production making this genotype more tolerant. The important binding residues in the ICPL 84023-H2O2complex (SER1, THR4, GLU23, and GLY13) have shown less fluctuation than the ICP 7035-H2O2 complex (SER1, THR4, and GLU23). Overall, our results showed that amino acid residue glycine in ICPL 84023 APX gene has a high binding affinity with H2O2 which could be a key factor associated with waterlogging stress tolerance in pigeon pea.

Ascorbate peroxidase (APX) is a member of the family of heme-containing peroxidases having a similar structure with Cytochrome c peroxidase (CCP) that effectively scavenge cytosolic and chloroplastic hydrogen peroxide (H2O2) under various stresses. In this study, computational characterization and homology analysis of APX protein from waterlogging tolerant (ICPL 84023) and sensitive (ICP 7035) pigeon pea genotypes were carried out resulting in 100% homology with Glycine max in case of former and 99% in later genotypes respectively with 97.39% alignment coverage among each other. The model structure was further refined by various tools like PROCHECK, ProSA, and Verify3D. The planned model of the APX enzyme was then tested to dock with H2O2along with molecular dynamics (MD) simulation analysis. The docked complex of ICPL 84023 showed the best G-score (23.39 kcal/mol) in comparison to ICP 7035 (16.74 kcal/mol) depicting the higher production of APX for scavenging reactive oxygen species (ROS) production making this genotype more tolerant. The important binding residues in the ICPL 84023-H2O2complex (SER1, THR4, GLU23, and GLY13) have shown less fluctuation than the ICP 7035-H2O2 complex (SER1, THR4, and GLU23). Overall, our results showed that amino acid residue glycine in ICPL 84023 APX gene has a high binding affinity with H2O2 which could be a key factor associated with waterlogging stress tolerance in pigeon pea. [ABSTRACT FROM AUTHOR]

Summary: Tolerance of abiotic stress in woody plants is known to be constrained by biological trade‐offs between different forms of stress, especially shade and drought. However, there is still considerable uncertainty on the relationship between tolerances and the limits on tolerance combinations.Using the most extensive database available on shade, drought, waterlogging and cold tolerance for 799 northern hemisphere woody species, we determined the number of dimensions needed to summarise their tolerance combinations, and the best trade‐off model among those currently available, for description of the interdependence between tolerances.Two principal component analysis (PCA) dimensions summarised stress tolerance combinations. They defined a triangular stress tolerance space (STS). The first STS dimension reflected segregation between drought‐tolerant and waterlogging‐tolerant species. The second reflected shade tolerance, which is independent of the other tolerances. Cold tolerance scaled weakly with both dimensions. Tolerance combinations across the species in the database were limited by boundary‐line trade‐offs.The STS reconciles all major theories about trade‐offs between abiotic stress tolerances, providing a unified trade‐off model and a set of coordinates that can be used to examine how other aspects of plant biology, such as plant functional traits, change within the limits of abiotic stress tolerance. [ABSTRACT FROM AUTHOR]

Climate change is predicted to increase the probability of soil waterlogging due to severe rainfall, causing significant damage to soybean at the germination stage. Germination under waterlogging is also greatly influenced by temperature. To clarify the variation in germination responses of soybean genotypes to waterlogging at different temperatures, the seeds of 15 soybean genotypes were treated by soaking for 2 days at four temperatures: 21 °C, 23 °C, 25 °C, 27 °C and 29 °C. Differences in the germination rate (GR) and normal seedling rate (NSR) were observed among soybean genotypes after soaking treatments regardless of the temperature. Among the examined genotypes, Iyodaizu was classified as waterlogging tolerant at the germination stage, and Tachinagaha was classified as sensitive. Interestingly, through the analyses of recombinant inbred lines (RILs) developed from a cross between Tachinagaha and Iyodaizu, quantitative trait loci (QTLs) for root development under hypoxia at the seedling stage of soybean were detected on chromosome 12 (Chr.12).We investigated whether the candidate QTL region for root development is involved in seed waterlogging tolerance by using a near-isogenic line (NIL), NIL-9-4-5. Interestingly, under soaking treatment, the GR and NSR of NIL-9-4-5, carrying the candidate QTL region, was nearly the same as that of Iyodaizu and was significantly higher than that of Tachinagaha. These results may indicate that the candidate QTL region for root development under hypoxia at the seedling stage located on Chr.12 contributes to the seed waterlogging tolerance of soybean plants at the germination stage. [ABSTRACT FROM AUTHOR]

Salicylic acid (SA) is an endogenous growth regulator. It is vital for the growth and development, photosynthesis, disease resistance, and abiotic stress tolerance of plants. This study aimed to investigate the effects of exogenous SA on photosynthetic characteristics and antioxidant system in the four-leaf-stage waxy corn inbred seedlings SY-MY13 (waterlogging-resistant) and SY-XT1 (waterlogging-sensitive) under waterlogging stress. Waterlogging stress negatively influenced the morphology, plant height, biomass, photosynthetic characteristics, and chlorophyll content of waxy corn seedlings, obstructing their growth and development. SY-MY13 exhibited better growth and photosynthesis than SY-XT1 under waterlogging, this was due to SY-MY13 possessed excellent scavenging ability to reactive oxygen species (ROS). However, the application of exogenous SA could not only reduce the accumulation of ROS and regulate the activities of antioxidant enzymes but also improve photosynthesis in leaves and promote the growth of seedlings. Hence, the results revealed that the potential of SA as a promising exogenous growth regulator mediated physiological and photosynthetic adaptation of waxy corn seedlings under waterlogging stress, which might prove helpful for other plants suffering from waterlogging stress. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is an important crop around the world, but its growth and production can be severely limited by waterlogging. In response to waterlogging stress, elaborate regulatory mechanisms have evolved in maize under both natural and artificial selection. Some research efforts involving genetic, genomic, and molecular strategies have focused on waterlogging stress biology in maize. Waterlogging affects the morphology, anatomy, physiology, and biochemistry of maize. The ability to improve waterlogging tolerance in maize breeding programs hinges on a detailed understanding of the genetic basis for waterlogging tolerance in some maize lines. In this review, we summarize the current understanding of this genetic basis. [ABSTRACT FROM AUTHOR]