Maize Genomics and Genetics 2025, Vol.16, No.3, 119-128 http://cropscipublisher.com/index.php/mgg 126 Figure 1 Proposed model of ZmHSF20 function in conferring tolerance to heat stress in maize (Adopted from Li et al., 2024) Image caption: Under heat stress, ZmHSF20 transcripts and ZmHSF20 protein accumulate, leading to the direct transcriptional repression of ZmHSF4 and ZmCesA2 expression. In parallel, ZmHSF4 normally promotes the expression of ZmCesAs, such that heat treatment further decreases cellulose content in a ZmHSF20- and ZmHSF4-dependent manner (Adopted from Li et al., 2024) Based on the above research results, the research team proposed a maize high temperature stress response model with ZmHSF20 as the core: in the Zmhsf20 mutant, the expression levels of ZmHSF4 and ZmCesA2 increased, and ZmHSF4 further activated the expression of ZmCesA2, enhancing cellulose synthesis and cell wall-related gene expression, thereby improving cell wall stability and overall heat resistance (Li et al., 2024). This study not only reveals the key role of the ZmHSF20-ZmHSF4-ZmCesA2 regulatory network in maize heat tolerance, but also for the first time clarifies the function of cellulose synthesis in the heat tolerance mechanism, providing a new perspective for high temperature stress response. More importantly, this research result provides valuable genetic resources and theoretical basis for molecular breeding of heat-resistant maize varieties, and expands the technical path for improving crop heat tolerance. 6Summary Under the background of global warming, heat-resistant breeding of fresh corn has become a key direction to ensure the sustainable development of agriculture. High temperature stress not only affects the normal growth and development of corn, especially causing serious losses in pollen vitality and fruiting rate, but also seriously restricts the stable improvement of fresh food quality and economic benefits. Therefore, it has become an urgent need in current scientific research and production practice to cultivate high-yield, high-quality and heat-resistant corn varieties through systematic breeding methods. At present, the work of heat-resistant breeding of fresh corn has made initial progress. Breeders not only continuously optimize parent combinations through conventional hybridization and pedigree selection methods, but also begin to pay attention to the genetic potential of local varieties and wild germplasm resources in heat-resistant traits. At the same time, the construction of an efficient phenotypic screening system and the introduction of high-throughput screening technology have greatly improved the breeding efficiency. Especially in terms of germplasm innovation, local varieties and wild resources are regarded as an important treasure house for mining new heat-resistant genes, and their genetic diversity provides a solid foundation for improving the current breeding population.
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