Flooding Stress Research Articles

Seed Priming: A Strategy to Mitigate Flooding Stress in Pulses

Aim: This study delves into the multifaceted role of seed priming in mitigating flooding stress, with a specific focus on its applications in pulse crops.
 Area of Study: Through controlled hydration-dehydration cycles and the utilization of specific priming agents, seed priming emerges as a powerful tool to enhance germination seedling vigor and stress tolerance. The impact of flooding stress on pulse plants, encompassing morphological changes, physiological alterations, and yield reduction, underscores the urgency of developing effective mitigation strategies. Seed priming mechanisms, including enhanced nutrient uptake, activation of antioxidant defenses and hormonal modulation, are explored in detail. The study not only provides insights into the integration of seed priming into crop management practices but also offers practical recommendations for farmers and agricultural practitioners. The implications for agriculture and food security are significant, as seed-primed crops demonstrate increased resilience to environmental stresses, ensuring more stable yields. The economic implications for farmers, coupled with the potential for sustainable agricultural practices, highlight the transformative potential of seed priming in addressing global challenges.
 Conclusion: The dissemination of knowledge and implementation efforts are crucial for bridging the gap between research findings and on-field applications. Policymakers and stakeholders are urged to support and incentivize the adoption of seed priming technologies, contributing to the long-term resilience of crops, and ensuring global food security. In conclusion, seed priming stands as a promising solution, offering a pathway towards sustainable and resilient agricultural systems in the face of environmental challenges.

High effects of climate oscillations on population diversity and structure of endangered Myricaria laxiflora.

Exploring the effects of climate oscillations on the population diversity and structure of endangered organisms in the Three Gorges Reservoir (TGR) area is essential for hydrological environment changes on endangered organism evolution. Myricaria laxiflora is an endemic and endangered shrub restricted to the TGR along the banks of Yangtze River, China. Recently, six natural populations of this species were newly found upstream and downstream of the TGR, whose habitats have been dramatically changed by the summer flooding regulated by large dams. To study the water level fluctuations and climatic shifts on the genetic diversity and genetic differentiation of the six natural populations, 303 individuals from six populations were analyzed based on one nuclear DNA (ITS) and four chloroplast fragments (trnL-F, psbA-trnH, rps16, and rpl16). The phylogenetic tree and significant genetic divergence identified in the cpDNA and ITS with genetic isolation and limited gene flow among regions suggested that the six populations separated well to two groups distributed upstream and downstream. The MaxEnt modeling results indicated that obvious unidirectional eastward migration via Yangtze River gorges watercourse mediated from Last Interglacial to Last Glacial Maximum were showed with the narrow scale distributions of six remnant populations and nine extirpated populations. The initial habitat fragmentation could be triggered by the accumulation of local habitat loss of the impoundment of the TGR during the Present period and might remain stable restoration with bidirectional diffusion in the Future. Divergences among M. laxiflora populations might have been induced by the drastic changes of the external environment and limited seed/pollen dispersal capacity, as the results of long-term ecological adaptability of summer flooding stress. The haplotypes of nuclear gene could be used for population's differentiation and germplasm protection. This identified gene flow and range dynamics have provided support for the gene-flow and geology hypothesis. It is also crucial for rescuing conservation to understand the impact of environmental dynamics on endangered organism evolution.

Microbiome structure variation and soybean's defense responses during flooding stress and elevated CO2.

With current trends in global climate change, both flooding episodes and higher levels of CO2 have been key factors to impact plant growth and stress tolerance. Very little is known about how both factors can influence the microbiome diversity and function, especially in tolerant soybean cultivars. This work aims to (i) elucidate the impact of flooding stress and increased levels of CO2 on the plant defenses and (ii) understand the microbiome diversity during flooding stress and elevated CO2 (eCO2). We used next-generation sequencing and bioinformatic methods to show the impact of natural flooding and eCO2 on the microbiome architecture of soybean plants' below- (soil) and above-ground organs (root and shoot). We used high throughput rhizospheric extra-cellular enzymes and molecular analysis of plant defense-related genes to understand microbial diversity in plant responses during eCO2 and flooding. Results revealed that bacterial and fungal diversity was substantially higher in combined flooding and eCO2 treatments than in non-flooding control. Microbial diversity was soil>root>shoot in response to flooding and eCO2. We found that sole treatment of eCO2 and flooding had significant abundances of Chitinophaga, Clostridium, and Bacillus. Whereas the combination of flooding and eCO2 conditions showed a significant abundance of Trichoderma and Gibberella. Rhizospheric extra-cellular enzyme activities were significantly higher in eCO2 than flooding or its combination with eCO2. Plant defense responses were significantly regulated by the oxidative stress enzyme activities and gene expression of Elongation factor 1 and Alcohol dehydrogenase 2 in floodings and eCO2 treatments in soybean plant root or shoot parts. This work suggests that climatic-induced changes in eCO2 and submergence can reshape microbiome structure and host defenses, essential in plant breeding and developing stress-tolerant crops. This work can help in identifying core-microbiome species that are unique to flooding stress environments and increasing eCO2.

Differential leaf flooding resilience in Arabidopsis thaliana is controlled by ethylene signaling-activated and age-dependent phosphorylation of ORESARA1

The phytohormone ethylene is a major regulator of plant adaptive responses to flooding. In flooded plant tissues, ethylene quickly increases to high concentrations owing to its low solubility and diffusion rates in water. Ethylene accumulation in submerged plant tissues makes it a reliable cue for triggering flood acclimation responses, including metabolic adjustments to cope with flood-induced hypoxia. However, persistent ethylene accumulation also accelerates leaf senescence. Stress-induced senescence hampers photosynthetic capacity and stress recovery. In submerged Arabidopsis, senescence follows a strict age-dependent pattern starting with the older leaves. Although mechanisms underlying ethylene-mediated senescence have been uncovered, it is unclear how submerged plants avoid indiscriminate breakdown of leaves despite high systemic ethylene accumulation. We demonstrate that although submergence triggers leaf-age-independent activation of ethylene signaling via EIN3 in Arabidopsis, senescence is initiated only in old leaves. EIN3 stabilization also leads to overall transcript and protein accumulation of the senescence-promoting transcription factor ORESARA1 (ORE1) in both old and young leaves during submergence. However, leaf-age-dependent senescence can be explained by ORE1 protein activation via phosphorylation specifically in old leaves, independent of the previously identified age-dependent control of ORE1 via miR164. A systematic analysis of the roles of the major flooding stress cues and signaling pathways shows that only the combination of ethylene and darkness is sufficient to mimic submergence-induced senescence involving ORE1 accumulation and phosphorylation. Hypoxia, most often associated with flooding stress in plants, appears to have no role in these processes. Our results reveal a mechanism by which plants regulate the speed and pattern of senescence during environmental stresses such as flooding. Age-dependent ORE1 activity ensures that older, expendable leaves are dismantled first, thus prolonging the life of younger leaves and meristematic tissues that are vital to whole-plant survival.

'Against all floods': plant adaptation to flooding stress and combined abiotic stresses.

Current climate change brings with it a higher frequency of environmental stresses, which occur in combination rather than individually leading to massive crop losses worldwide. In addition to, for example, drought stress (low water availability), also flooding (excessive water) can threaten the plant, causing, among others, an energy crisis due to hypoxia, which is responded to by extensive transcriptional, metabolic and growth-related adaptations. While signalling during flooding is relatively well understood, at least in model plants, the molecular mechanisms of combinatorial flooding stress responses, for example, flooding simultaneously with salinity, temperature stress and heavy metal stress or sequentially with drought stress, remain elusive. This represents a significant gap in knowledge due to the fact that dually stressed plants often show unique responses at multiple levels not observed under single stress. In this review, we (i) consider possible effects of stress combinations from a theoretical point of view, (ii) summarize the current state of knowledge on signal transduction under single flooding stress, (iii) describe plant adaptation responses to flooding stress combined with four other abiotic stresses and (iv) propose molecular components of combinatorial flooding (hypoxia) stress adaptation based on their reported dual roles in multiple stresses. This way, more future emphasis may be placed on deciphering molecular mechanisms of combinatorial flooding stress adaptation, thereby potentially stimulating development of molecular tools to improve plant resilience towards multi-stress scenarios.

Millmeter-wave irradiation regulates mRNA-expression and the ubiquitin-proteasome system in wheat exposed to flooding stress

The irradiation with millimeter-wave (MMW) of wheat seeds promotes root growth under flooding stress; however, its role is not completely clarified. Nuclear proteomics was performed, to reveal the role of MMW irradiation in enhancing flooding tolerance. The purity of nuclear fractions purified from roots was verified. Histone, which is a protein marker for nuclear-purification efficiency, was enriched; and cytosolic ascorbate peroxidase was reduced in the nuclear fraction. The principal-component analysis of proteome displayed that the irradiation of seeds affected nuclear proteins in roots grown under flooding stress. Proteins detected using proteomic analysis were verified using immunoblot analysis. Histone H3 accumulated under flooding stress; however, it decreased to the control level by irradiation. Whereas the ubiquitin accumulated in roots grown under stress when seeds were irradiated. These results suggest that MMW irradiation improves wheat-root growth under flooding stress through the regulation of mRNA-expression level and the ubiquitin-proteasome system. SignificanceTo reveal the role of millimeter-wave irradiation in enhancing flooding tolerance in wheat, nuclear proteomics was performed. The principal-component analysis of proteome displayed that irradiation of seeds affected nuclear proteins in roots grown under flooding stress. Proteins detected using proteomic analysis were verified using immunoblot analysis. Histone H3 accumulated under flooding stress; however, it decreased to the control level with irradiation. Whereas the ubiquitin accumulated in roots grown under stress when seeds were irradiated. These results suggest that millimeter-wave irradiation improves wheat-root growth under flooding stress through the regulation of mRNA-expression level and the ubiquitin-proteasome system.

Application of multiomics analysis to plant flooding response.

Flooding, as a natural disaster, plays a pivotal role in constraining the growth and development of plants. Flooding stress, including submergence and waterlogging, not only induces oxygen, light, and nutrient deprivation, but also alters soil properties through prolonged inundation, further impeding plant growth and development. However, hypoxia (or anoxia) is the most serious and direct damage to plants caused by flooding. Moreover, flooding disrupts the structural integrity of plant cell walls and compromises endoplasmic reticulum functionality, while hindering nutrient absorption and shifting metabolic processes from normal aerobic respiration to anaerobic respiration. It can be asserted that flooding exerts comprehensive effects on plants encompassing phenotypic changes, transcriptional alterations, protein dynamics, and metabolic shifts. To adapt to flooding environments, plants employ corresponding adaptive mechanisms at the phenotypic level while modulating transcriptomic profiles, proteomic characteristics, and metabolite levels. Hence, this study provides a comprehensive analysis of transcriptomic, proteomic, and metabolomics investigations conducted on flooding stress on model plants and major crops, elucidating their response mechanisms from diverse omics perspectives.

Registration of R16‐45 as a flood‐tolerant, high‐yielding soybean germplasm line

AbstractR16‐45 (Reg. no. GP‐526, PI 704118) is a high‐yielding soybean [Glycine max (L.) Merr.] breeding line with flood tolerance at early reproductive stages released as germplasm by the Arkansas Agricultural Experiment Station in 2023. It is an F2 selection from the cross between the flood‐tolerant breeding line R07‐6669 and the high‐yielding Arkansas cultivar ‘UA 5612’. R16‐45 is a conventional (non‐genetically modified) soybean with a relative maturity of 5.6. Plants have determinate growth habit, white flower color, and buff hilum color. It has gray pubescence, tan pod wall at maturity, and yellow cotyledons with a dull yellow seed coat. R16‐45 showed high yield potential and broad adaptability across 17 environments in Arkansas and other southern states, with an average of 4145 kg ha−1 (95.3% of the checks’ mean). Six years of field evaluations for flooding tolerance showed that R16‐45 is consistently tolerant to 8‐to‐10‐day flooding stress at the R1/R2 growth stages (average flood damage score of 3.6, compared with 6.0 from the reference checks). In addition, R16‐45 is resistant to stem canker. Given substantial yield losses associated with flooding stress and stem canker, R16‐45 is a valuable germplasm source for public and private soybean breeding programs attempting to incorporate novel genetic diversity into their breeding pipeline.

Biochemical Analysis to Understand the Flooding Tolerance of Mutant Soybean Irradiated with Gamma Rays.

Flooding stress, which reduces plant growth and seed yield, is a serious problem for soybean. To improve the productivity of flooded soybean, flooding-tolerant soybean was produced by gamma-ray irradiation. Three-day-old wild-type and mutant-line plants were flooded for 2 days. Protein, RNA, and genomic DNA were then analyzed based on oppositely changed proteins between the wild type and the mutant line under flooding stress. They were associated with cell organization, RNA metabolism, and protein degradation according to proteomic analysis. Immunoblot analysis confirmed that the accumulation of beta-tubulin/beta-actin increased in the wild type under flooding stress and recovered to the control level in the mutant line; however, alpha-tubulin increased in both the wild type and the mutant line under stress. Ubiquitin was accumulated and genomic DNA was degraded by flooding stress in the wild type; however, they were almost the same as control levels in the mutant line. On the other hand, the gene expression level of RNase H and 60S ribosomal protein did not change in either the wild type or the mutant line under flooding stress. Furthermore, chlorophyll a/b decreased and increased in the wild type and the mutant line, respectively, under flooding stress. These results suggest that the regulation of cell organization and protein degradation might be an important factor in the acquisition of flooding tolerance in soybean.

Responses of the maize rhizosphere soil environment to drought-flood abrupt alternation stress.

Changes in the soil environment in the root zone will affect the growth, development and resistance of plants. The mechanism underlying the effect of drought and flood stress on rhizosphere bacterial diversity, soil metabolites and soil enzyme activity is not clear and needs further study. To analyze the dynamic changes in bacteria, metabolites and enzyme activities in the rhizosphere soil of maize under different drought-flood abrupt alternation (DFAA) stresses, the barrel test method was used to set up the 'sporadic light rain' to flooding (referring to trace rainfall to heavy rain) (DFAA1) group, 'continuous drought' to flooding (DFAA2) group and normal irrigation (CK) group from the jointing to the tassel flowering stage of maize. The results showed that Actinobacteria was the most dominant phylum in the two DFAA groups during the drought period and the rewatering period, and Proteobacteria was the most dominant phylum during the flooding period and the harvest period. The alpha diversity index of rhizosphere bacteria in the DFAA2 group during the flooding period was significantly lower than that in other stages, and the relative abundance of Chloroflexi was higher. The correlation analysis between the differential genera and soil metabolites of the two DFAA groups showed that the relative abundance of Paenibacillus in the DFAA1 group was higher during the drought period, and it was significantly positively correlated with the bioactive lipid metabolites. The differential SJA-15 bacterium was enriched in the DFAA2 group during the flooding period and were strongly correlated with biogenic amine metabolites. The relative abundances of Arthrobacter, Alphaproteobacteria and Brevibacillus in the DFAA2 group were higher compared with DFAA1 group from rewatering to harvest and were significantly positively correlated with hydrocarbon compounds and steroid hormone metabolites. The acid phosphatase activity of the DFAA1 group was significantly higher than that of the DFAA2 group during the flooding period. The study suggests that there is a yield compensation phenomenon in the conversion of 'continuous drought' to flooding compared with 'sporadic light rain', which is related to the improvement in the flooding tolerance of maize by the dominant bacteria Chloroflexi, bacterium SJA-15 and biogenic amine metabolites. These rhizosphere bacteria and soil metabolites may have the potential function of helping plants adapt to the DFAA environment. The study revealed the response of the maize rhizosphere soil environment to DFAA stress and provided new ideas for exploring the potential mechanism of crop yield compensation under DFAA.

Physiological, Epigenetic, and Transcriptome Analyses Provide Insights into the Responses of Wheat Seedling Leaves to Different Water Depths under Flooding Conditions

Flooding stress, including waterlogging and submergence, is one of the major abiotic stresses that seriously affects the growth and development of plants. In the present study, physiological, epigenetic, and transcriptomic analyses were performed in wheat seedling leaves under waterlogging (WL), half submergence (HS), and full submergence (FS) treatments. The results demonstrate that FS increased the leaves’ hydrogen peroxide (H2O2) and malondialdehyde (MDA) contents and reduced their chlorophyll contents (SPAD), photosynthetic efficiency (Fv/Fm), and shoot dry weight more than HS and WL. In addition, FS increased catalase (CAT) and peroxidase (POD) activities more than HS and WL. However, there were no significant differences in the contents of H2O2, MDA, SPAD, and Fv/Fm, and the activities of superoxide dismutase (SOD) and POD between the HS and WL treatments. The changes in DNA methylation were related to stress types, increasing under the WL and HS treatments and decreasing under the FS treatment. Additionally, a total of 9996, 10,619, and 24,949 genes were differentially expressed under the WL, HS, and FS treatments, respectively, among which the ‘photosynthesis’, ‘phenylpropanoid biosynthesis’, and ‘plant hormone signal transduction’ pathways were extensively enriched under the three flooding treatments. The genes involved in these pathways showed flooding-type-specific expression. Moreover, flooding-type-specific responses were observed in the three conditions, including the enrichment of specific TFs and response pathways. These results will contribute to a better understanding of the molecular mechanisms underlying the responses of wheat seedling leaves to flooding stress and provide valuable genetic and epigenetic information for breeding flood-tolerant varieties of wheat.

Plant–plant interactions vary greatly along a flooding gradient in a dam-induced riparian habitat

Plant–plant interactions under extreme environmental stress are still controversial. The stress gradient hypothesis (SGH) proposes that facilitation prevails under extreme environmental stresses, while an alternative view states that facilitation collapses or even switches back to competition at the extreme end of stress gradients. However, how the relationship between plant–plant interaction and periodic extreme flooding stress varies and its underlying mechanism are still unclear in a dam-regulated riparian ecosystem. We established a controlled experiment using two dominant species pairs (Cynodon dactylon–Cyperus rotundus and C. dactylon–Xanthium sibiricum) in the water level fluctuating zone of the Three Gorges Dam to examine their growth responses to the periodic extreme flooding stress. The results showed that as flooding stress increased, the competitive effect of C. dactylon on X. sibiricum shifted to facilitation, whereas the effect of X. sibiricum on C. dactylon maintained a strong inhibition. The plant height of X. sibiricum was the most important driver of the interaction between X. sibiricum and C. dactylon along the flooding gradient. The net effect of C. dactylon on C. rotundus shifted from neutral to negative, and the inhibitory effect of C. rotundus on C. dactylon became stronger at the extreme end of flooding stress. The root biomass of the two species was the key trait regulating their interaction with increasing flooding stress. Overall, the SGH was partially supported along our periodic extreme flooding stress gradient. Aboveground resource (light) might be the dominant factor driving the response of the interaction between annual plants and perennial clonal plants to periodic flooding stress, whereas belowground resource (water and nutrients) was probably the dominant factor for perennial clonal plants. Our study will help to further understand the environmental responses of plant–plant relationships and their regulatory mechanism, and the succession of riparian plant communities under extreme environmental changes, providing a basic theoretical basis and data support for the ecological restoration and management of riparian wetland vegetation.

A balancing act: ERFVII feedback loops finetune the flooding stress response.

A balancing act: ERFVII feedback loops finetune the flooding stress response.

Plant Adaptation to Flooding Stress under Changing Climate Conditions: Ongoing Breakthroughs and Future Challenges.

Climate-change-induced variations in temperature and rainfall patterns are a serious threat across the globe. Flooding is the foremost challenge to agricultural productivity, and it is believed to become more intense under a changing climate. Flooding is a serious form of stress that significantly reduces crop yields, and future climatic anomalies are predicted to make the problem even worse in many areas of the world. To cope with the prevailing flooding stress, plants have developed different morphological and anatomical adaptations in their roots, aerenchyma cells, and leaves. Therefore, researchers are paying more attention to identifying developed and adopted molecular-based plant mechanisms with the objective of obtaining flooding-resistant cultivars. In this review, we discuss the various physiological, anatomical, and morphological adaptations (aerenchyma cells, ROL barriers (redial O2 loss), and adventitious roots) and the phytohormonal regulation in plants under flooding stress. This review comprises ongoing innovations and strategies to mitigate flooding stress, and it also provides new insights into how this knowledge can be used to improve productivity in the scenario of a rapidly changing climate and increasing flood intensity.

Flood Tolerance of Hybrid Napier (Pennisetum purpureum x Pennisetum glaucum) Cultivars

A pot culture study was conducted from February to May 2020 at the Agronomy Farm, Department of Agronomy, College of Agriculture, Vellanikkara, Kerala to study the effects of short-term flooding on the growth, physiology, and yield of four high-yielding cultivars of hybrid napier (Pennisetum purpureum x Pennisetum glaucum) cultivated in Kerala. The experiment followed a 4 x 2 factorial Completely Randomized Design with three replications. The treatments comprised two factors: varieties and flooding treatments. The four hybrid napier varieties used in the study were CO-3 (V1), CO-5 (V2), IGFRI -3 (V3), and Suguna (V4). The flooding treatments included no flooding (F0) as a control and short-term flooding stress treatment (F1) at three different growth stages: 30 days after planting (DAP), 60 DAP and just after the first harvest (75 DAP). Flooding stress was imposed for seven days by inundating water in the pots up to 3-4 cm above the soil level. Flooding at all three stages resulted in a significant reduction in plant height, tiller number, leaf number and above-ground biomass for all varieties. A severe reduction in growth and yield parameters was observed when flooding stress was imposed immediately after the first harvest. Among the varieties, CO-5 had the tallest plants, followed by Suguna, CO-3, and IGFRI-3. When exposed to flooding stress, variety CO-5 was also found to be significantly superior in terms of above-ground biomass production, followed by CO-3. Superoxide dismutase (SOD) activity increased in all varieties due to flooding stress, with a pronounced increase observed in Suguna. Variety CO-5, which exhibited greater plant height and above-ground biomass production, was found to be more tolerant to flooding stress, while variety IGFRI-3, with a dwarf plant stature and the lowest biomass yield, was identified as sensitive to short-term flooding stress.

Physiological and transcriptomic analysis of the mangrove species Kandelia obovata in response to flooding stress

Flooding stress on mangroves is growing continually with rising sea level. In this study, the physiology and transcriptome of the mangrove species Kandelia obovata under flooding stress were analyzed. With increasing inundation time, malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), soluble sugar (SS), soluble protein (SP), and proline (Pro) content declined, while peroxidase (POD) and ascorbate peroxidase (APX) activity rose significantly. According to the KEGG pathway enrichment analysis, upregulated differentially expressed genes (DEGs) were enriched in the plant hormone signaling pathway. Furthermore, MYB44 and MYB108 genes from the MYB transcription factor family and RAP2.12, DREB2B, and ERF4 genes from the AP2/ERF family were up-regulated under flooding conditions. A strong correlation was established between the expression levels of 12 DEGs under flooding stress and RNA sequencing data and was verified by qRT-PCR. These results provide new insights into the molecular mechanism of K. obovata in response to flooding stress.

Selection of reference genes and expression of key genes involved in response to short-term soil flooding stress in Prunus persica rootstock ‘Tsukuba 1’

The hypoxic environment directly impacts energy production, growth, and plant development. Under this condition, plants need to rely on anaerobic metabolism to maintain ATP production. These responses are modulated by complex molecular mechanisms that are responsible for gene expression to avoid plant damage. In order to carry out gene expression studies using the real-time PCR technique (RT-qPCR), it is necessary to normalize the data based on optimal reference gene(s) to experimental conditions. Thus, the first aim of this study was to identify likely reference genes and then determine their stability. Besides, we investigated whether adjusting root energy that ‘Tsukuba 1’ plays in the hypoxia is compatible with tolerance or susceptibility to short-term soil flooding. For that, ‘Tsukuba 1’ was submitted to two irrigation treatments: 1) non-flooded, and 2) flooded (1, 2, 4, 8, 16, and 32 h). A comprehensive analysis of performance and stability showed as most stable reference genes, PpTEF2 and PpTUA for roots and PpPLA2 and PpCYP2 for leaves. Conversely, PpTUB and PpEf1α, and PpTUA genes were not suitable reference genes for roots and leaves, respectively. Under short-term soil flooding, ‘Tsukuba 1’ roots generate energy anaerobically firstly through lactic-acid metabolism and then by alcoholic in 2 and 8 h, respectively. In summary, moderate tolerance to short-term soil flooding was observed in peach cultivar ‘Tsukuba 1’, mainly due to stimulation of glycolysis and up-regulation of key gene expression responsible for pivotal pathways involved in energy and ethylene metabolism. However, other physiological and metabolic traits/responses needed to be investigated to confirm this trend.

Comparative Transcriptome Analysis Reveals the Molecular Mechanism of Salt Combined with Flooding Tolerance in Hybrid Willow (Salix matsudana × alba)

Plants in coastal areas often face the combined stress of salt and flooding, which can cause severe damage. The impact of multiple stresses on plant growth and survival is greater than that of individual stresses. However, the molecular responses of hybrid willow (Salix matsudana × alba) to the combination of salt and flooding have not been well understood. In this study, we conducted a comparative transcriptome analysis to investigate the molecular mechanism underlying the tolerance of hybrid willow to salt-flooding. Seedings were, respectively, treated with 200 mM NaCl and flooded with water or 200 mM NaCl solution for 3 d, 10 d, and 17 d. We identified 1842, 3350, and 2259 differentially expressed genes (DEGs) regulated by hybrid willow under single salt stress, single flooding stress, and combined salt and flooding stress, respectively. Many DEGs detected in single salt- and flooding-treated plants were expressed differentially after the combined salt and flooding. Most of the shared transcripts exhibited similar fold changes in common molecular responses such as detoxification of reactive oxygen species (ROS) and signaling pathways related to calcium, phytohormones, and protein kinases, which were also observed in plants exposed to each stress individually. Additionally, a large number of specific DEGs were identified under salt-flooding stress, primarily associated with cell wall remodeling, osmotic adjustments, stress signaling, primary metabolism, and ROS scavenging. KEGG (Kyoto Encyclopedia of Genes and Genomes) annotation indicated that hybrid willow leaves responded to salt-flooding stress mainly through phytohormone signaling and MAPK signaling pathways. Overall, this study provides new insights into the molecular mechanisms underlying the response of Salix species to multiple stresses and identifies potential candidate genes for enhancing the performance of hybrid willows.

Effect of nicotinic acid in defence of wheat plants against hypoxia under flooding stress

Aim. The aim of the research was to investigate the induction of the Triticum aestivum L. non-specific tolerance by nicotinic acid to hypoxia during the flooding stress. Methods. Winter wheat plants cv. Ladyzhynka were grown in laboratory conditions and had been treated by nicotinic acid solution then flooding stress started. The hydrogen peroxide content in leaves and morphometric parameters were measured during the experimental period. Results. It is shown that the influence of the nicotinic acid was essential during the first hour of the flooding stress. After 96 hours of flooding stress the nicotinic acid balanced the hydrogenous peroxide level in wheat leaves close to control. Conclusions. Nicotinic acid decreased the stress level in wheat plants under flooding conditions via regulation of hydrogen peroxide content in leaves. The regulation of the hydrogen peroxide level could influence on plant adaptation to flooding stress and conditions of high humidity, decrease the damage of tissues and prevent their loss under flooding. Nicotinic acid could be used as a perspective component for compound combinations to induce complex stimulation of plant tolerance and defense against plant biotic and abiotic stresses.

Ispanakta Sel Baskını Stresine Karşı Tolerant Genotiplerin Belirlenmesi

Abiotic stress factors generate negative effects on agricultural production daily. With the effect of global warming, the floods that have increased recently not only affected human life negatively but also caused great losses in plant development. For this reason, developing tolerant plants against flooding stress is the most critical approach reducing yield and quality losses. The present study aimed to determine the genotypes that are tolerant of flooding stress by using the agro-morphological and physiological characteristics of the commercial varieties and S5-level spinach breeding materials. In the study, 13-day flood stress was applied to 48 hybrid cultivars and 23 spinach genotypes at the S5 stage during the seedling period. As a result, in addition to the adverse effects of flood stress on plant growth, it was determined that the tolerance was different between genotypes. In the light of the results obtained, SWA0760 F1 among commercial varieties was found to be the most tolerant variety to flood stress. At the same time, genotypes 14, 9, 21, 15, 4 and 10 from breeding lines were promising genotypes that were tolerant to flooding stress. As a result, it is predicted that the inclusion of the genotypes used in the study as parents in hybrid cultivar breeding will make significant contributions to the development of tolerant cultivars against flood stress.