Mechanisms of Plant Regulation against Environmental Stress

Dear Colleagues,

Plants are exposed to ever-changing environments to which they must adjust. Abiotic stresses include drought, extreme temperature, UV radiation, strong light, high salinity, low soil nutrient levels, etc., which can affect plant growth at all phenological developmental stages, from the morphological to the molecular level. On the other hand, plants have evolved special methods, including stress avoidance and tolerance, and undergo various morphological, physiological, biochemical, and molecular modifications in order to cope with different abiotic stresses. Due to the continuous climate change and environmental deterioration caused by human activity, environmental stresses have become a key threat to plant growth and development. Drought stress, salt stress, nutrient imbalances (including mineral toxicity and deficiencies), and temperature extremes represent significant environmental factors that limit the productivity of plants around the world. Therefore, it is important to understand the mechanisms that control different processes and that underlie abiotic stress tolerance in plants. This Special Issue will focus on the morphological, physiological, biochemical, and molecular modifications of plants under various abiotic stresses. With the maturity of biotechnology, especially gene editing and transgenic technology, it has become increasingly easy to change plant traits. An increasing number of researchers are successfully creating stress-tolerant plants using biotechnology. The identification and characterization of candidate genes associated with stress resistance in plants is also of interest. Through this Special Issue, we hope to increase our understanding of the molecular mechanisms underlying the responses of plants to abiotic stresses, and provide guidance for establishing stress-resistant plant varieties.

Dr. Weibing Zhuang
Dr. Tao Wang
Dr. Peng Wang
Guest Editors

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• abiotic stress
• physiological mechanisms
• molecular mechanisms
• plant growth and development
• stress-resistant plants
• genes associated with stress resistance

Title: Exogenous Brassinosteroid Mediates Nitrogen Metabolism, Ionic Equilibrium, and Phytohormonal Response in Cucumber (Cucumis sativus L.) Under Salt-Alkali Stress: Insights for Enhanced Stress Tolerance
Authors: Dr. Wenjing Nie
Affiliation: Yantai Engineering Research Center for Plant Stem Cell Targeted Breeding烟台植物干细胞定向育种工程研究中心, Shandong Institute of Sericulture山东省蚕桑研究所, Yantai 264001 烟台 264001, Shandong Province 山东省, China 中国
Abstract: Using the hydroponic method with Hoagland nutrient solution, salt-alkali stress conditions were simulated with NaHCO3, and the damage caused to cucumber seedlings by this stress was alleviated by the exogenous addition of 24-epibrassinolide (EBR). Our study revealed that NaHCO3 stress significantly facilitated the accumulation of Na+ in cucumber plants, while reducing the levels of K+, Ca2+, and Mg2+, consequently leading to a significant increase in the Na+/K+, Na+/Mg2+, and Na+/Ca2+ ratios. Exogenous EBR mitigated the accumulation of Na+ in cucumber plants under alkali stress, resulting in reduced Na+/K+, Na+/Mg2+, and Na+/Ca2+ ratios, along with increased levels of K+, Ca2+, and Mg2+, thereby maintaining ion balance in cucumber plants under alkali stress conditions. NaHCO3 stress induced nitrogen metabolism imbalance in cucumber plants, evidenced by significant reductions in the activities of nitrate reductase (NR), glutamine synthetase (GS), glutamate synthase (GOGAT), glutamate oxaloacetate transaminase (GOT), and glutamate pyruvate transaminase (GPT), alongside a fluctuation in glutamate dehydrogenase (GDH) activity, accumulation of NH4+, and significant decreases in NO3--N and total N content. Exogenous EBR alleviated the inhibition of NR, GS, GOGAT, GOT, and GPT activities induced by alkali stress, mitigated the decline in GDH activity caused by prolonged alkali stress, and enhanced the NO3--N and total N content in cucumber seedlings, consequently alleviating the toxicity of NH4+ induced by alkali stress. NaHCO3 stress led to an accumulation of ABA and reduction in IAA content in cucumber seedlings, while exogenous EBR increased the levels of IAA, GA3, as well as IAA/ABA and GA3/ABA ratios under NaHCO3 stress conditions, thereby maintaining hormonal balance in cucumber seedlings. Overall, exogenous EBR improved the salt-alkali tolerance of cucumber plants by regulating nitrogen metabolism, ion balance, and phytohormonal responses.