Phenylalanine Ammonia-Lyase GhPAL9 Confers Resistance to Verticillium Wilt in Cotton.

Verticillium wilt (VW), induced by the soil-borne fungus , represents a significant threat to global cotton production. Phenylalanine ammonia-lyase (PAL) is an essential enzyme in lignin metabolism that helps plants defend themselves against pathogenic fungal. Nonetheless, its role in imparting resistance to in cotton required further investigation. This study identified the (GH_D04G1247) as a crucial gene in cotton resistance to via RNA-seq analysis, demonstrating significant upregulation in the resistant variety Xinluzao84. Bioinformatics analysis revealed the conserved evolutionary relationship of GhPAL9 with PAL homologs across various species and highlighted stress-responsive cis-elements in its promoter region. The expression of was rapidly activated in roots, stems, and leaves following infection with , peaking between 2 and 8 h post inoculation (hpi). Silencing through virus-induced gene silencing (VIGS) technology intensified disease symptoms, elevated relative fungal biomass, and diminished lignin accumulation, thereby affirming its function in cotton resistance to . The overexpression of in improved resistance to , and the OE- transgenic lines demonstrated reduced disease severity and diminished relative fungal biomass. The results gave us new information about how VW resistance at the molecular level, which established that acted as a positive regulator to increase resistance to VW via lignin accumulation.