Cotton miR319b-Targeted TCP4-Like Enhances Plant Defense Against by Activating Transcription Expression.

Teosinte branched1/Cincinnata/proliferating cell factor (TCP) transcription factors play important roles in plant growth and defense. However, the molecular mechanisms of TCPs participating in plant defense remain unclear. Here, we characterized a cotton TCP4-like fine-tuned by miR319b, which could interact with NON-EXPRESSER OF PATHOGEN-RELATED GENES 1 (NPR1) to directly activate () expression, facilitating plant resistance against . mRNA degradome data and GUS-fused assay showed that mRNA was directedly cleaved by ghr-miR319b. Knockdown of ghr-miR319b increased plant resistance to , whereas silencing increased plant susceptibility by the virus-induced gene silencing (VIGS) method, suggesting that is a positive regulator of plant defense. According to the electrophoretic mobility shift assay and GUS reporter analysis, GhTCP4-like could transcriptionally activate expression, resulting in increased salicylic acid (SA) accumulation. Yeast two-hybrid and luciferase complementation image analyses demonstrated that interacts with , which can promote transcriptional activation in expression according to the GUS reporter assay. Together, these results revealed that GhTCP4-like interacts with GhNPR1 to promote expression through fine-tuning of ghr-miR319b, leading to SA accumulation, which is percepted by NPR1 to increase plant defense against . Therefore, GhTCP4-like participates in a positive feedback regulation loop of SA biosynthesis via NPR1, increasing plant defenses against fungal infection.