Physiology of Plant Responses to Water Stress and Related Genes: A Review

Abstract

Drought and waterlogging seriously affect the growth of plants and are considered severe constraints on agricultural and forestry productivity; their frequency and degree have increased over time due to global climate change. The morphology, photosynthetic activity, antioxidant enzyme system and hormone levels of plants could change in response to water stress. The mechanisms of these changes are introduced in this review, along with research on key transcription factors and genes. Both drought and waterlogging stress similarly impact leaf morphology (such as wilting and crimping) and inhibit photosynthesis. The former affects the absorption and transportation mechanisms of plants, and the lack of water and nutrients inhibits the formation of chlorophyll, which leads to reduced photosynthetic capacity. Constitutive overexpression of 9-cis-epoxydioxygenase (NCED) and acetaldehyde dehydrogenase (ALDH), key enzymes in abscisic acid (ABA) biosynthesis, increases drought resistance. The latter forces leaf stomata to close in response to chemical signals, which are produced by the roots and transferred aboveground, affecting the absorption capacity of CO2, and reducing photosynthetic substrates. The root system produces adventitious roots and forms aerenchymal to adapt the stresses. Ethylene (ETH) is the main response hormone of plants to waterlogging stress, and is a member of the ERFVII subfamily, which includes response factors involved in hypoxia-induced gene expression, and responds to energy expenditure through anaerobic respiration. There are two potential adaptation mechanisms of plants (“static” or “escape”) through ETH-mediated gibberellin (GA) dynamic equilibrium to waterlogging stress in the present studies. Plant signal transduction pathways, after receiving stress stimulus signals as well as the regulatory mechanism of the subsequent synthesis of pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) enzymes to produce ethanol under a hypoxic environment caused by waterlogging, should be considered. This review provides a theoretical basis for plants to improve water stress tolerance and water-resistant breeding.

Plants’ Physio-Biochemical and Phyto-Hormonal Responses to Alleviate the Adverse Effects of Drought Stress: A Comprehensive Review

“…Reducing leaf relative water content, turgor loss, and stomatal closure are the frequent consequences of drought stress in Barley (Hordeum vulgare L.) [51]. During drought, leaf wilting and abscission reduce water loss via transpiration [17,63]. When there is a significant water shortage, cell enlargement in higher plants is hampered by the interruption of xylem water flow.…”

“…Lower RWC reduces leaf water potential, causing stomata to contract. T ration is the primary mechanism governing leaf temperature; increasing stoma sistance minimizes the transpiration rate in rice leaves due to ABA content and in leaf temperature [63]. In a Triticum aestivum L., the leaf's relative water content in throughout development and decreases as dry matter accumulates as the leaf ag Water-stressed wheat and rice plants contained less water content as compared to wheat and rice plants that were grown under controlled conditions [71].…”

Wheat Crop under Waterlogging: Potential Soil and Plant Effects

“…Adverse environments, such as waterlogged soil, may induce several changes at morphological and physiological levels in plants. To enhance waterlogging tolerance, a vast number of stress response genes are activated and essential functional proteins are synthesized [ 122 , 123 ]. Wei et al, (2021) [ 124 ] observed a considerable down-regulation of photosynthesis-related genes (e.g., PsbQ , PsbO , and petF ) and light-harvesting chlorophyll protein complex genes (e.g., LHCB1 , LHCB3 , LHCB5 , LHCA1 , and LHCA4 ) in two wheat genotypes in response to waterlogging.…”

Water Deficit and Excess and the Main Physiological Disorders in Agricultural Crops

“…Under water excess conditions, the signals originating from the root system are transferred to the soil, causing the stomata to close and, consequently, minimizing the photosynthetic rate and the absorption and assimilation of CO2 (Wu et al, 2022). Moreover, water stress results in a significant accumulation of osmolytes in plants, decreasing the plant osmotic potential to maintain water status and physiological activities required by plants (Mukherjee et al, 2022).…”