In an era characterized by rapidly changing and less-predictable weather conditions fueled by the climate crisis, understanding the mechanisms underlying local adaptation in plants is of paramount importance for the conservation of species. As the frequency and intensity of extreme precipitation events increase, so are the flooding events resulting from soil water saturation. The subsequent onset of hypoxic stress is one of the leading causes of crop damage and yield loss. By combining genomics and remote sensing data, it is now possible to probe natural plant populations that have evolved in different rainfall regimes and look for molecular adaptation to hypoxia. Here, using an environmental genome-wide association study (eGWAS) of 934 non-redundant georeferenced Arabidopsis ecotypes, we have identified functional variants of the gene MED25 BINDING RING-H2 PROTEIN 1 (MBR1). This gene encodes a ubiquitinprotein ligase that regulates MEDIATOR25 (MED25), part of a multiprotein complex that interacts with transcription factors that act as key drivers of the hypoxic response in Arabidopsis, namely the RELATED TO AP2 proteins RAP2.2 and RAP2.12. Through experimental validation, we show that natural variants of MBR1 have different effects on the stability of MED25 and, in turn, on hypoxia tolerance. This study also highlights the pivotal role of the MBR1/MED25 module in establishing a comprehensive hypoxic response. Our findings show that molecular candidates for plant environmental adaptation can be effectively mined from large datasets. This thus supports the need for integration of forward and reverse genetics with robust molecular physiology validation of outcomes.

Soil flooding, manifesting as submergence or waterlogging stress, significantly impacts plant species composition and agricultural productivity, particularly in regions with low rainfall. This study investigates the biochemical responses of two peanut (Arachis hypogaea L.) genotypes, DH-86 and GJG-32, under waterlogging stress. The experiment involved in-vivo pot trials where peanut plants were subjected to continuous waterlogging for 12 days at the flowering stage. Biochemical analyses of leaves conducted and revealed significant alterations in enzyme activities and metabolite concentrations. Key findings include variations in superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPOD), alpha-amylase, invertase, acid phosphomonoesterase activities, and changes in starch, proline, reducing sugars, and chlorophyll content. SOD, CAT, and GPOD activities exhibited differential responses between genotypes, highlighting DH-86's quicker recovery post-waterlogging. Notably, DH-86 demonstrated higher resilience, reflected in its rapid normalization of biochemical parameters, while GJG-32 showed prolonged stress effects. These findings underscore the importance of antioxidative enzyme systems in mitigating oxidative damage induced by waterlogging. This study enhances our understanding of the biochemical adaptations of peanut genotypes to waterlogging stress, offering valuable insights for breeding programs focused on improving flood tolerance in crops.

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.

Sudden wilt syndrome of chilli, an emerging and destructive disorder, is characterized by an abrupt appearance that has increased in Indo-Gangetic alluvial plains over the past decade. The primary cause associated with the problem is water stagnation that creates hypoxic conditions in the root zone, and the plant mortality is further aggravated by soil-borne fungi Fusarium oxysporum. The effects of sudden wilt on chilli roots were studied morphologically and histologically, using root scanning, optical microscopy and electron microscopy. Significant changes with respect to root length, projected area, number of root tips and root segments, average root diameter as well as estimated volume of roots were observed via root scanning of healthy and diseased root samples. Through optical microscopy of sections of the microtome-cut root junctions displayed normal epidermis in healthy plants, while swollen cells indicated stress in the diseased plants. Cells of laterals and root tips in healthy plants were intact and stained strongly, but because of damaged tissues, cells in diseased plants were macerated and stained weakly. Root tips of healthy plants contained mitotic zones, whereas diseased root tips lacked mitotic zones. Electron microscopy studies revealed that sudden wilt had an adverse impact on xylem diameter, stele diameter, epidermal thickness and cortex thickness as evidenced by significantly lesser values of these parameters. The present study is the first systematic attempt to examine the morphological, histological and ultrastructural changes in chilli in response to sudden wilt syndrome.

Priming enables plants to respond more promptly, minimise damage, and survive subsequent stress events. Here, we aimed to assess the efficacy of priming and cross-priming in mitigating the stress caused by waterlogging and/or dehydration in soybeans (Glycine max). Soybean plants were cultivated in a greenhouse in plastic pots in which soil moisture was maintained at pot capacity through irrigation. The first stress was applied in plants at the vegetative stage for 5 days and involved either dehydration or waterlogging, depending on the treatment. Subsequently, the plants were irrigated or drained and maintained at pot capacity until the second stress. For the second stress, the conditions were repeated in plants at the reproductive stage. We then evaluated the levels of hydrogen peroxide (H2O2), lipid peroxidation, total soluble sugars (TSS), amino acids, proline, and starch, and the activity of antioxidant, fermentative, and aminotransferase enzymes. Under waterlogging and dehydration, priming and cross-priming significantly increased the activity of antioxidant enzymes and the levels of TSS, amino acids, and proline while reducing H2O2 concentration and lipid peroxidation. Under waterlogging, priming suppressed fermentative activity and increased carbohydrate content. This demonstrates that soybean plants activate their defence systems more promptly when subjected to priming.

Background: MicroRNA (miRNA) plays an important role in hepatic stellate cell (HSCs) activation and liver fibrosis. The purpose of this study is to explore the effect of hypoxia on the differential expression of mRNAs and miRNAs in rat HSCs. Methods: HSC-T6 cells were treated with cobalt chloride (CoCl2), and the activity of HSC-T6 cells was measured by the CCK-8 assay. The mRNA expression levels of hypoxia inducible factor-1 alpha (HIF-1 alpha), collagen type I, transforming growth factor-131 (TGF-131), and Smad7 were measured by RT-qPCR. The protein expression levels of HIF-1 alpha, Bax, Bcl-2, and caspase-3 were assayed by western blot. We used basal medium and 400 mu mol/L CoCl2 medium to treat HSC-T6 cells for 48 h. Cells were harvested after 48 h to extract RNA. Transcriptome sequencing was performed to investigate differentially expressed miRNAs and mRNAs (fold change >2; P<0.05). Bioinformatics analysis was performed to predict the functions of differentially expressed miRNAs and mRNAs. Further, we used RT-qPCR to detect the expression of mRNAs and miRNAs to confirm the accuracy of sequencing. Results: With the increase of CoCl2 concentration, the activity of HSC-T6 cells decreased (P<0.05). The mRNA expression levels of HIF-1 alpha, collagen I, TGF-131, and Smad7, and the protein expressions levels of HIF-1 alpha, Bax, caspase-3, and the Bcl-2/Bax ratio were increased compared with the control group (P<0.05), while the expression of Bcl-2 decreased. A total of 54 miRNAs (20 upregulated and 34 downregulated) and 1,423 mRNAs (685 upregulated and 738 downregulated) were differentially expressed in the 400 mu mol/L CoCl2 medium group compared to the control basal medium group. Further bioinformatics analysis demonstrated that the differentially expressed mRNAs and miRNAs were mainly enriched in the synthesis of extracellular matrix. In addition, we used RT-qPCR to detect the expression of mRNAs and miRNAs to confirm the accuracy of sequencing. Conclusions: Our results presented the profiles of mRNAs and miRNAs in hypoxia-induced HSC-T6 cells in rats, the signaling pathways, and co-expression networks. These findings may suggest novel insights for the early diagnosis and treatment of HSC activation and liver fibrosis.