Integrated genome and expression of the TGA family in Gossypium hirsutum reveals GhTGA12 could positively regulate systemic acquired resistance

Abstract

Cotton diseases pose a serious threat to yield and fiber quality. Systemic acquired resistance (SAR) is a crucial and prolonged immune response to pathogen infection; yet, its regulatory mechanisms remain poorly understood in cotton. Here, 35 TGACG binding (TGA) transcription factors were identified in Gossypium hirsutum, classifying them into five groups based on phylogenetic analysis, conserved motifs, and gene structures. Among them, GhTGA12, a group II member, emerged as a novel disease-associated transcription factor based on RNA-seq analysis under biotic stress conditions. GhTGA12 encodes a nuclear protein with 11 exons and 10 introns, harboring the conserved TGA-specific domains (bZIP, DOG1, Q1, and Q2). GhTGA12 has transcriptional activation activity through its N-terminal region and could be triggered by Pst DC3000. While GhTGA12-overexpressing Arabidopsis did not exhibit enhanced resistance after a single Pst DC3000 challenge, it showed significantly increased resistance upon Pst DC3000 pretreatment, consistent with SAR activation. These lines also exhibited elevated ROS levels and increased PR expression levels (PR1, PR2, PR5, and GRXS13). Additionally, GhTGA12 physically interacts with GhNPR1, a key regulator of SAR. Collectively, this study identifies GhTGA12 as a critical SAR-positive regulator via ROS signaling, PR gene activation, and GhNPR1 interaction, offering new targets for enhancing disease resistance in cotton.