Maize Genomics and Genetics 2025, Vol.16, No.3, 108-118 http://cropscipublisher.com/index.php/mgg 109 heat-resistant genes. By integrating the research results at the molecular and physiological levels, this study is expected to provide a theoretical basis for the development of corn varieties that adapt to climate warming, thereby promoting sustainable agricultural production. 2 Impact of Heat Stress on Maize Growth and Development 2.1 Effects on morphological traits High temperature and heat damage is a natural disaster that may occur in corn production. If there are disastrous climatic conditions such as continuous high temperature and drought or cloudy and rainy weather with little sunshine, it will seriously affect the growth and development, resulting in reduced yield or even total crop failure. When corn is in a meteorological condition where the daily average temperature is greater than or equal to 35 ℃ and lasts for more than 5 days, and ineffective rainfall lasts for more than 8 days, high temperature and heat damage will inevitably occur. High temperature stress will significantly change the morphological development of corn plants, usually manifested as reduced plant height, reduced leaf area and inhibited root growth. During the flowering and pollination period of corn, drought and high temperature delay the development of anthers, missing the mature stage of female spike filaments, that is, the flowering period is not met; the improper use of herbicides causes herbicide damage or other reasons that lead to uneven development of plants in the field, which will undoubtedly affect the quality of pollination; the lack of phosphorus in plants causes poor anther development. High temperature during the vegetative growth period will inhibit the expansion and elongation of cells, resulting in short plants and reduced biomass accumulation. Common high temperature stress responses also include leaf curling and premature senescence, which further reduce the photosynthetic area and affect the photosynthetic efficiency and yield of crops. For example, maize hybrids such as ZD309 exhibit phenotypes such as plant dwarfing and leaf curling under heat stress conditions, indicating that their growth is significantly inhibited (Liu et al., 2022). High temperatures also inhibit root development, manifested as reduced root length and root volume, thereby limiting the absorption of water and nutrients (Xue et al., 2024). These adverse morphological changes not only affect the growth and development of individual plants, but also lead to weakened group growth and reduced overall field performance. 2.2 Physiological and biochemical responses to heat stress Under high temperature stress, corn will initiate a series of physiological and biochemical reactions to alleviate damage and maintain cell homeostasis. The impact of high temperature stress on corn is not limited to changes in morphological characteristics, but also triggers a series of complex physiological and biochemical reactions to maintain cell homeostasis and improve stress resistance. Studies by Xi et al. (2022) and Xie et al. (2022) showed that the photosynthesis system is one of the most significant physiological processes affected by heat stress. High temperature can lead to a decrease in chlorophyll content, destroy the thylakoid membrane structure, reduce the activity of photosystem II (PSII), and thus inhibit the electron transport chain and carbon assimilation process. The decrease in Rubisco enzyme activity and the reduction in carbon dioxide supply caused by stomatal closure further weaken the photosynthetic efficiency. At the same time, heat stress will cause a large amount of reactive oxygen species (ROS) such as O2 - andH2O2 to accumulate in plants, inducing oxidative stress. To reduce the toxic effects of ROS, corn activates the antioxidant defense system, including superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), which effectively remove free radicals and protect cell membrane structure and enzyme system. Plants also alleviate cell dehydration and membrane lipid peroxidation and enhance cell stability by accumulating osmotic regulating substances such as proline, soluble sugar and betaine. Heat shock proteins (HSPs) are also an important component of corn's response to high temperature stress. For example, HSP70, HSP90 and small molecule heat shock proteins (sHSPs) can assist in the correct folding and repair of proteins, prevent heat-induced protein aggregation, and improve cell heat resistance.
RkJQdWJsaXNoZXIy MjQ4ODYzNA==