SEVEN IN ABSENTIA Ubiquitin Ligases Positively Regulate Defense Against in .

Ubiquitination is a post-translational regulatory mechanism that controls a variety of biological processes in plants. The E3 ligases confer specificity by recognizing target proteins for ubiquitination. Here, we identified SEVEN IN ABSENTIA (SINA) ubiquitin ligases, which belong to the RING-type E3 ligase family, in upland cotton (). Twenty-four s were characterized, and the expression levels of , , and were upregulated at 24 h after inoculation with . ubiquitination assays indicated that the three GhSINAs possessed E3 ubiquitin ligase activities. Transient expression in leaves showed that they localized to the nucleus. And yeast two-hybrid (Y2H) screening revealed that they could interact with each other. The ectopic overexpression of , , and independently in resulted in increased tolerance to , while individual knockdowns of , , and compromised cotton resistance to the pathogen. Thus, , , and act as positive regulators of defense responses against in cotton plants.