Cotton miR319b-Targeted TCP4-Like Enhances Plant Defense Against Verticillium dahliae by Activating GhICS1 Transcription Expression
Pei Jia, Ye Tang, Guang Hu, Yonggang Quan, Aimin Chen, Naiqin Zhong, Qingzhong Peng, Jiahe Wu
Abstract
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 isochorismate synthase 1 ( ICS1 ) expression, facilitating plant resistance against Verticillium dahliae . mRNA degradome data and GUS-fused assay showed that GhTCP4-like mRNA was directedly cleaved by ghr-miR319b. Knockdown of ghr-miR319b increased plant resistance to V. dahliae , whereas silencing GhTCP4-like increased plant susceptibility by the virus-induced gene silencing (VIGS) method, suggesting that GhTCP4-like is a positive regulator of plant defense. According to the electrophoretic mobility shift assay and GUS reporter analysis, GhTCP4-like could transcriptionally activate GhICS1 expression, resulting in increased salicylic acid (SA) accumulation. Yeast two-hybrid and luciferase complementation image analyses demonstrated that GhTCP4-like interacts with GhNPR1 , which can promote GhTCP4-like transcriptional activation in GhICS1 expression according to the GUS reporter assay. Together, these results revealed that GhTCP4-like interacts with GhNPR1 to promote GhICS1 expression through fine-tuning of ghr-miR319b, leading to SA accumulation, which is percepted by NPR1 to increase plant defense against V. dahliae . Therefore, GhTCP4-like participates in a positive feedback regulation loop of SA biosynthesis via NPR1, increasing plant defenses against fungal infection.