Cotton Genomics and Genetics 2025, Vol.16, No.3, 137-147 http://cropscipublisher.com/index.php/cgg 142 QTL was found on chromosome A10, which contains the CG02 gene. Both genes were later experimentally verified to be related to resistance. In a larger GWAS study, scientists also found a key region on chromosome Dt11. This region contains multiple excellent alleles and gene clusters that are closely related to disease resistance, including L-type lectin domain receptor kinase (Zhang et al., 2021b). Therefore, QTL mapping and GWAS can provide reliable targets for cotton breeding and are also suitable for marker-assisted selection and genetic engineering (Li et al., 2017a). It can be said that functional genomics and gene editing tools allow us to find important genes related to disease resistance more quickly, and also provide a powerful means for breeding disease-resistant cotton varieties. 7 Crosstalk and Shared Mechanisms in Response to Verticillium and Fusarium 7.1 Common signaling pathways activated by both pathogens When cotton is infected by Verticillium dahliae or Fusarium oxysporum, it activates several of the same signaling pathways to defend itself. A major mechanism is that cotton uses receptor kinases (LYKs) with lysozyme structures and chitin-sensing receptor kinase 1 (CERK1) to recognize chitin in the cell wall of pathogens. Chitin is an important component of the fungal cell wall. The cell wall-associated kinase GhWAK7A can interact with the sensing complex composed of GhCERK1-GhLYK5, promote their binding and phosphorylation, and then activate subsequent defense responses (Wang et al., 2020). In addition, some common signaling pathways are also activated, such as the MAPK kinase pathway, hormone signals such as salicylic acid (SA), jasmonic acid (JA), abscisic acid (ABA), and the regulatory system of reactive oxygen species (ROS) metabolism (Yi et al., 2023). 7.2 Shared downstream effectors and defense genes Whether it is Verticillium or Fusarium invasion, cotton will be induced to activate some of the same defense-related genes and proteins. Such genes include NBS-LRR type resistance genes, PR (pathogenesis-related) proteins, enzymes that regulate ROS production, and factors related to strengthening the cell wall (Mo et al., 2021). For example, the fatty acid transporter GhSTR1, which is expressed more after infection by both pathogens, can play a balancing role between defense and growth and plays a significant role in broad-spectrum resistance. In addition, some genes that regulate phenylpropanoid metabolism and lignin synthesis are also activated at the same time. These genes help strengthen the cell wall and produce antibacterial substances (Billah et al., 2021). In particular, salicylic acid-dependent defense pathways are critical in both diseases, such as the upregulation of genes such as GbCNL130 (Li et al., 2021). 7.3 Potential for cross-resistance breeding strategies Some QTL regions and candidate genes that are effective against both Verticillium wilt and Fusarium wilt have been discovered, which shows that breeding through cross-resistance strategies is feasible. GWAS studies have found that there are some overlapping QTL regions related to both diseases on chromosomes c16 and c19, which are rich in NBS-LRR gene clusters (Abdelraheem et al., 2019). Genes such as GhWAK7A and GhSTR1 play a role in resisting both pathogens. After verification, these genes have further proved the possibility of breeding broad-spectrum disease-resistant varieties by "stacking" such common resistance genes (Cheng et al., 2025). If these universal molecular mechanisms are rationally applied to breeding, it is expected to improve cotton's long-term resistance to multiple wilt diseases and reduce the impact of diseases on cotton yield. 8 Case Study Molecular Resistance in Xinjiang Cotton Varieties 8.1 Selection of resistant cotton cultivars and local pathogen strains In Xinjiang, Verticillium wilt and Fusarium wilt have a great impact on cotton yield. Therefore, finding disease-resistant cotton varieties has always been one of the key tasks. Through field trials and nursery observations, researchers found that JK1775 is a disease-resistant variety, while Z8 is susceptible to Verticillium wilt (Figure 2). These two varieties are often used in related research. In terms of Fusarium wilt, disease-resistant sea island cotton varieties such as 06-146 are used to study their genetic resistance mechanisms. In addition, transgenic colored cotton with GAFP (Gastrodia antifungal protein) genes has also been tested in Xinjiang. These lines have shown resistance to Verticillium wilt and Fusarium wilt in actual planting. For example, the two lines LB5007 and ZB5020 are particularly outstanding in disease prevention (Liu et al., 2004). However, the survey
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