Cotton SNARE complex component GhSYP121 regulates salicylic acid signaling during defense against Verticillium dahliae

Syntaxin of plant (SYP) plays a crucial role in SNARE-mediated membrane trafficking during endocytic and secretory pathways, contributing to the regulation and execution of plant immunity against pathogens. Verticillium wilt is among the most destructive fungal diseases affecting cotton worldwide. However, information regarding SYP family genes in cotton is scarce. Through genome-wide identification and transcriptome profiling, we identified GhSYP121, a Qa SNARE gene in Gossypium hirsutum. GhSYP121 is notably induced by Verticillium dahliae, the causal agent of Verticillium wilt in cotton, and acts as a negative regulator of defense against V. dahliae. This is evidenced by the reduced resistance of GhSYP121-deficient cotton and the increased susceptibility of GhSYP121-overexpressing lines. Furthermore, the activation of the salicylic acid (SA) pathway by V. dahliae is inversely correlated with the expression level of GhSYP121. GhSYP121 interacts with its cognate SNARE component, GhSNAP33, which is required for the penetration resistance against V. dahliae in cotton. Collectively, GhSYP121, as a member of the cotton SNARE complex, is involved in regulating the SA pathway during plant defense against V. dahliae. This finding enhances our understanding of the potential role of GhSYP121 in these distinct pathways that contribute to plant defense against V. dahliae infection.