Plant Gene and Trait 2024, Vol.15, No.1, 1-7 http://genbreedpublisher.com/index.php/pgt 2 Figure 1 Physiological changes in wheat and barley genotypes in response to drought stress (Adopted from Sallam et al., 2019) The response of wheat to drought also involves the regulation of plant growth and development. In a water-constrained environment, wheat plants grow at a slower rate, including reduced leaf growth, stem elongation, and root development, to conserve water and adjust the allocation of carbon resources. At this time, plants may selectively retain or cut back some metabolic processes related to growth and development in order to adapt to drought stress. The metabolic pathways of plants are also adjusted under drought conditions. Wheat may have increased the activity of the antioxidant enzyme system in response to oxidative damage due to drought. At the same time, hormone levels also change, for example, the accumulation of abscisic acid may affect plant growth and development and stress response. The adjustment and change of these physiological processes work together to coordinate plant adaptation and help wheat better cope with the challenges of arid environments. 2.2 Reaction at the molecular level The molecular responses and regulatory changes of wheat under drought stress are very complex. In order to adapt to drought environment, plants regulate gene expression and signal transduction networks through a variety of molecular mechanisms, which involve the regulation of expression of many key genes, especially genes regulating stress response and antioxidant response (Rijal et al., 2021). At the molecular level, wheat can regulate multiple pathways to adapt to drought stress, and ABA (abscisic acid) pathway is a key signaling mechanism in stress response pathway, which can regulate the expression of multiple stress response genes. By regulating gene expression, ABA pathway activates stress-responsive genes such as LEA protein gene family, which encode proteins that help maintain cell stability and improve wheat tolerance to drought. The ABA signaling pathway also triggers stomatal closure, which is critical for reducing water evaporation. Under drought conditions, wheat can limit water loss in this way and improve leaf water use efficiency. Wheat also increases the surface area of the root system by regulating the growth pattern of the root system and secretes root secretions, thereby improving the water absorption capacity in response to drought stress. Drought conditions can lead to oxidative stress, producing excessive reactive oxygen species, causing damage to plant cells, and wheat will enhance the antioxidant system by activating the ABA pathway to reduce oxidative damage.
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