Long-term exposure to slightly elevated air temperature alleviates the negative impacts of short term waterlogging stress by altering nitrogen metabolism in cotton leaves

Phenotyping for waterlogging tolerance in crops: current trends and future prospects

Yield losses to waterlogging are expected to become an increasingly costly and frequent issue in some regions of the world. Despite the extensive work that has been carried out examining the molecular and physiological responses to waterlogging, phenotyping for waterlogging tolerance has proven difficult. This difficulty is largely due to the high variability of waterlogging conditions such as duration, temperature, soil type, and growth stage of the crop. In this review, we highlight use of phenotyping to assess and improve waterlogging tolerance in temperate crop species. We start by outlining the experimental methods that have been utilized to impose waterlogging stress, ranging from highly controlled conditions of hydroponic systems to large-scale screenings in the field. We also describe the phenotyping traits used to assess tolerance ranging from survival rates and visual scoring to precise photosynthetic measurements. Finally, we present an overview of the challenges faced in attempting to improve waterlogging tolerance, the trade-offs associated with phenotyping in controlled conditions, limitations of classic phenotyping methods, and future trends using plant-imaging methods. If effectively utilized to increase crop resilience to changing climates, crop phenotyping has a major role to play in global food security.

Short-term soil-waterlogging contributes to cotton cross tolerance to chronic elevated temperature by regulating ROS metabolism in the subtending leaf

Chronic elevated temperature and soil-waterlogging events often occur concomitantly in the Yangtze River Valley; however, a clear understanding of the effects of aforementioned co-occurring stresses on antioxidant defense in cotton has not been attained. To address this, two temperature conditions during the whole flowering and boll development periods, and three soil-waterlogging levels (0, 3, 6 d) starting on the day of anthesis were established. In the current study, no siginificant difference was observed on plant performance for 3 d soil-waterlogging, whereas 6 d soil-waterlogging event and elevated temperature in isolation negatively affected plant performance (i.e. leaf area declined by 33.3% and 14.7% in AW₆ (soil waterlogging for 6 d under ambient temperature regime) and EC (soil well-watered (SRWC(75 ± 5) %) under elevated temperature for 2-3 °C) relative to AC (soil well-watered (SRWC(75 ± 5) %) under ambient temperature regime)) and induced ROS (reactive oxygen species) production and scavenging mechanisms in the subtending leaf of cotton. SOD (superoxide dismutase), CAT (catalase), and POX (peroxidase) activities were increased, and ASA (ascorbic acid) concentration was enhanced due to higher H₂O₂ (hydrogen peroxide) and O₂^- accumulations. Whereas, APX (ascorbate peroxidase), DHAR (dehydroascorbate reductase) and GR (glutathione reductase) activities were inhibited under elevated temperature regime or waterlogging event, especially in the treatment of EW₆ (soil waterlogging for 6 d under elevated temperature for 2-3 °C), which resulted in increasing H₂O₂ concentration and higher O₂^- generation rate. However, plants acclimated to a short-term waterlogging stress (3 d) performed a cross tolerance to chronic elevated temperature regime (leaf number increased by 11.4%, whereas the abscission rate decreased by 4.6% in EW₃ (soil waterlogging for 3 d under elevated temperature for 2-3 °C) compared with EC (soil well-watered (SRWC(75 ± 5) %) under elevated temperature for 2-3 °C)). Moreover, plants undergone a brief soil-waterlogging (3 d) induced higher GR activity and increased ASA concentration, along with enhanced SOD, CAT, POX activities, limiting H₂O₂ and O₂^- accumulation and reducing oxidative damage to membrane lipids as evidenced by reduced MDA (malondialdehyde) concentration when cotton was subsequently exposed to chronic elevated temperature regime.

Analysis of the regulation networks in grapevine reveals response to waterlogging stress and candidate gene-marker selection for damage severity

Owing to the climate change impacts, waterlogging is one of the most hazardous abiotic stresses to crops, which also can result in a serious reduction in the quantity and quality of grape berry and wine production during the rainy season. Therefore, the exploration of the response mechanism of grape to waterlogging is necessary, for which the analysis of the transcriptomic regulation networks of grapevine leaves in response to waterlogging stress was carried out. In this study, 12 634 genes were detected in both waterlogging stress and control grapevine plants, out of which 6837 genes were differentially expressed. A comparative analysis revealed that genes functioning in the antioxidant system, glycolysis and fermentation pathway, chlorophyll metabolism, amino acid metabolism and hormones were activated to reduce injury to grapes under the waterlogging stress. Meanwhile, genes encoding class-2 non-symbiotic haemoglobin were determined as important in waterlogging acclimation. Additionally, the expression variations of three marker genes were found to be informative and can be used to predict the viability of the grapevines subjected to waterlogging. This research not only probes the molecular mechanism underlying grapevine waterlogging tolerance but also puts forward an idea about the application of gene expression information to practical management.