Maize Genomics and Genetics 2025, Vol.16, No.3, 108-118 http://cropscipublisher.com/index.php/mgg 111 antioxidant defense, osmotic regulation, hormone signaling, and protein homeostasis. Among them, HSFs are the most intensively studied class of heat-responsive transcription factors, which can recognize and bind to heat shock elements (HSEs) and rapidly induce the expression of defense genes such as heat shock proteins (HSPs). In maize, members such as ZmHSFA2, ZmHSFB1, and ZmHSFC1 have been shown to play an important role in the heat stress regulatory network. In addition to HSFs, WRKY transcription factors regulate ROS scavenging and antioxidant enzyme expression by binding to W-box elements, and participate in the regulation of hormone signaling pathways. NAC transcription factors not only regulate plant development, but also regulate programmed cell death and stress response gene expression in heat stress (Xi et al., 2022). MYB family members, especially R2R3-type MYBs, are involved in regulating secondary metabolism, stomatal regulation, and antioxidant defense systems. DREB transcription factors activate gene expression related to osmotic protection and stress signaling pathways by binding to DRE/CRT elements. bZIP transcription factors are widely involved in ABA-mediated signal regulation, promoting protein folding, ROS homeostasis maintenance and stress defense response. Heat stress response is a complex network composed of coordinated regulation of multiple transcription factors, signal interactions and feedback regulation. The integration of transcriptomics and functional genomics research helps to identify key transcription factor "regulatory hubs" in maize, providing targets and theoretical support for molecular breeding of heat-resistant varieties (Kumar et al., 2023; Li et al., 2024). 3.3 Signal transduction pathways in heat stress response Heat shock factors are not only key transcriptional regulatory factors themselves, but also form a complex regulatory network with other signal molecules. For example, the transcription factor ZmHsf17 can interact with members of the HsfA2 subclass and jointly participate in the transcriptional regulation of genes related to lipid metabolism and membrane stability, playing an important role in ensuring the integrity of cell membrane structure under high temperature conditions (Zhang et al., 2024). The bZIP signaling pathway also plays an important role in the heat stress response of maize. In particular, the Unfolded Protein Response (UPR) mediated by bZIP60 is activated under high temperature stress conditions, which can alleviate heat-induced protein misfolding and photosynthetic system damage in cells by regulating the expression of heat shock protein genes and chlorophyll decomposition processes (Li et al., 2015; 2020). Heat stress signal transduction pathways usually also include other classic mechanisms, such as calcium ion signaling (Ca2+ signaling), reactive oxygen species (ROS) signaling, and plant hormone signaling networks (such as ABA, ethylene, JA, etc.). These signaling systems enhance the heat tolerance of plants as a whole by rapidly transmitting heat stress information, activating antioxidant enzyme systems, and regulating stomatal behavior and cellular metabolic processes. 4 Physiological and Biochemical Adaptations to Heat Stress 4.1 Antioxidant defense mechanisms Reactive oxygen species (ROS) are key signaling molecules that enable cells to respond quickly to different stimuli. High temperature stress often leads to oxidative stress, manifested by the accumulation of reactive oxygen species (ROS) such as superoxide anion radicals (O2 -), hydrogen peroxide (H2O2), and hydroxyl radicals (OH·), which ultimately lead to biofilm peroxidation, protein structure destruction, and DNA damage. The production of ROS in plants is precisely regulated by an antioxidant enzyme system composed of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), ascorbate peroxidase (APX), and peroxidase (GPX), as well as a non-enzyme system composed of antioxidants such as ascorbic acid (ASA) and glutathione (CSH), so that ROS in plants is maintained at a physiological level that plants can tolerate. Corn effectively alleviates the damage caused by ROS by enhancing enzymatic and non-enzymatic antioxidant mechanisms. The study by Yang et al. (2021) found that ZmRPP13-LK3 responded significantly to high temperature stress and was regulated by ABA. The cAMP catalyzed by it significantly increased the activity of antioxidant protection enzymes, heat shock proteins (HSPs), ABA-related transcription factors and other gene expressions in corn leaves; it proved that ZmRPP13-LK3 interacted with ABC2, suggesting that the cAMP
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