Maize Genomics and Genetics 2025, Vol.16, No.6, 294-303 http://cropscipublisher.com/index.php/mgg 295 Against this backdrop, CRISPR/Cas9 genome editing technology has gradually been regarded as a breakthrough. It is not like traditional methods that require "slow work to produce fine results", nor is it as controversial as genetically modified organisms. What we want to explore is its application potential in the drought resistance improvement of corn. By precisely knocking out or modifying drought-sensitive genes, this technology may be able to accelerate the breeding process of drought-resistant varieties to a certain extent. This study will discuss the current research progress, key target genes, and the feasibility of incorporating CRISPR/Cas9 into breeding programs, and further analyze the challenges and prospects involved. 2 Mechanisms of Drought Sensitivity in Maize 2.1 Drought perception and signal transduction pathways in maize When corn is short of water, it first "detects" environmental changes. This reaction is not completed instantaneously but is accompanied by the interweaving of a series of molecular signals. The first to be activated is often the abscisic acid (ABA) signaling pathway-which is mentioned in almost all drought studies, but the response rate and intensity vary in different tissues. When water begins to decrease, ABA accumulation prompts stomata to gradually close to reduce water loss, while simultaneously initiating a series of stress-related genes (Jiang et al., 2025). In this pathway, receptors (PYL/RCAR), protein phosphatases (PP2Cs), and kinases (SnRK2s) act like a relay team, transmitting signals layer by layer and ultimately guiding cells to respond (Cao et al., 2021). However, ABA is not a "solo". Other hormones such as auxin and cytokinin also get involved. Sometimes they cooperate and sometimes they "go against", thus making the response of corn more flexible. Calcium signals and MAPK cascade reactions act like amplifiers, converting external drought signals into stronger cellular responses (Wang et al., 2022). Overall, this system is more like a constantly fine-tuned network rather than a simple one-way path. 2.2 Role of stress-responsive genes and their regulatory networks After the drought came, the gene expression in corn was almost "rewritten", and thousands of genes began to change (Zhao et al., 2025). Some genes are responsible for directing-transcription factors such as WRKY, NAC, DREB, bZIP, etc. Some act directly, such as antioxidant enzymes SOD, CAT, and POD, as well as proteins involved in hormone synthesis or signal transduction. Transcription factors check and coordinate with each other, forming a complex regulatory network, which ultimately enables corn to maintain osmotic balance, metabolic adjustment and defense response under stress. For instance, ZmWRKY30 and ZmDIR11 can enhance antioxidant and hormone metabolism, thereby improving drought resistance (Figure 1). However, there are also opposite examples. For instance, when ZmPL1 or ZmPP2C-A10 is overexpressed, corn becomes more vulnerable instead (Gu et al., 2024). Furthermore, the natural differences in gene regulatory elements and expression dynamics also lead to significant variations in the performance of different varieties under drought conditions (Liu et al., 2020). In other words, drought resistance is not a single "genetic victory", but the result of the entire genetic network. 2.3 Physiological traits influenced by genetic sensitivity to drought From the appearance, corn with poor drought resistance often has withered, curled leaves, and even yellowing leaves, as well as a decline in photosynthesis and a reduction in biomass-these signs are all familiar to everyone. However, if one looks deeper, it will be found that the accumulation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) is the key issue, and they are particularly severe in sensitive corn (Yousaf et al., 2023). If the antioxidant system is weak, the cell structure is prone to damage. Those genotypes that can hold up usually have stronger antioxidant enzyme activity, more stable osmotic regulation ability (such as accumulation of proline and soluble sugar), and can also maintain a better photosynthetic level under stress. These seemingly physiological differences are actually closely related to the response efficiency of signaling pathways and the regulation of related genes.
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