Rice Genomics and Genetics 2024, Vol.15, No.1, 19-27 http://cropscipublisher.com/index.php/rgg 25 The differences in morphological structure have a significant impact on drought resistance. Reasonable adjustment of root system structure can enable plants to better obtain water and nutrients, thereby improving drought resistance. The adjustment of leaf morphology slows down water transpiration rate, reduces water loss, and helps plants maintain water balance under drought conditions. Therefore, the differences in morphological structure enable plants to adapt more flexibly to different soil moisture conditions, enhancing their survival ability in arid environments. When comprehensively analyzing the differences in the morphological structure of roots and leaves, it is necessary to pay attention to the variations under different varieties and ecological environments. Meanwhile, examples or tables can be used to demonstrate the comparison and adjustment of root and leaf morphology of rice under drought conditions, in order to more intuitively illustrate the impact of these differences on plant drought tolerance. This comparison helps to gain a deeper understanding of the adaptive strategies of rice in the face of drought stress. 4.2 Differences and similarities in physiological processes The root system and leaves play complementary yet differentiated physiological roles in water regulation. The root system is mainly responsible for the absorption and supply of water in the soil, while the leaves regulate water transpiration and gas exchange through stomata. Under drought conditions, roots and leaves exhibit some common responses, but there are also significant differences. Under drought stress, the root system aims to maximize the exploration of water resources in the soil by adjusting the growth and distribution of root hairs, as well as adjusting the root structure. This adaptation strategy aims to increase the surface area of the root system to improve the efficiency of water absorption. On the other hand, by adjusting the opening and closing of stomata, leaves limit the transpiration of water and reduce water loss. The adjustment of leaf morphology may include reducing leaf surface area, adjusting stomatal density and distribution to reduce water evaporation on the surface. However, the differences between roots and leaves in water regulation are mainly reflected in their functional division of labor. The main task of the root system is to absorb and supply water from the soil, while the leaves focus more on regulating transpiration to maintain water balance. This difference enables plants to respond more harmoniously to drought stress throughout the entire water transport system, ensuring effective water utilization and allocation (Corso et al., 2020). The antioxidant system is a crucial physiological process in both roots and leaves, used to combat oxidative stress and maintain cellular redox balance. The similarities and differences in antioxidant systems in roots and leaves reflect their specific adaptability in plant resistance to drought stress. The antioxidant system in the root system mainly alleviates oxidative stress by regulating the activity of related enzymes. For example, enzymes such as superoxide dismutase (SOD), peroxidase (POD), and ascorbic acid peroxidase (APX) are activated in the root system to eliminate excessive oxygen free radicals and protect cell membranes and other biomolecules from oxidative damage. The antioxidant system in leaves also plays a crucial role, but exhibits different characteristics in certain aspects. Due to the fact that leaves face the external environment more directly, their antioxidant system may be more flexible and respond quickly to oxidative stress caused by drought. The antioxidant enzymes in leaves may undergo more complex regulation to adapt to physiological activities such as photosynthesis and gas exchange. 4.3 Comparison at the molecular level At the molecular level, the gene expression of roots and leaves exhibits certain similarities and differences, reflecting their different physiological roles and adaptation strategies in response to drought stress. Research has shown that there are similarities in the expression patterns of some genes in roots and leaves, especially those related to antioxidant and dehydrating hormone responses. The common regulation of these genes may be an important component of plant adaptation to oxidative stress and drought.
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