Effects of Drought Stress on Agricultural Plants, and Molecular Strategies for Drought Tolerant Crop Development

In natural environment, plants are subjected to encounter various kinds of abiotic stresses. Drought stress is the inevitable factor that onsets without the identification of any borders or without any warning. It is the most significant environmental stress brought on by fluctuations in temperature, light intensity, and low rainfall. It deteriorates plant biomass production, quality, and energy, leading to adverse effects on the growth and production of plants. Abiotic stress causes physical damage, physiological and biochemical disruptions, and molecular changes. Depending on the species, plants have developed a variety of intricate resistance and adaptive mechanisms, including physiological and biochemical responses, to deal with this stress. Plants have acquired a variety of strategies to deal with drought stress, including altered stomatal conductance and distribution, altered growth pattern and structural dynamics, reduced transpiration loss, increased root length, accumulation of compatible solutes, increased transpiration efficiency, osmotic and hormonal regulation, and delayed senescence. Breeding strategies, molecular and genomics perspectives, emphasizing the alteration of omics technology metabolomics, proteomics, genomics, transcriptomics, genomics, and phenomics that improve plant stress tolerance, and marker-assisted selections are the major drought stress alleviation measures. Additionally, CRISPR-Cas method has opened up new dimensions and promises in developing drought tolerant plants. In the present chapter, the evidence on plant responses to drought stresses are explained and their possible defense measures are discussed.