The Cotton miR477-CBP60A Module Participates in Plant Defense Against Verticillium dahlia.

Previous reports have shown that, when Verticillium dahliae localizes at the root surface, many microRNAs (miRNAs) were identified at the early induction stage. Here, we constructed two groups from two timepoints of small RNA (sRNA) in cotton root responses to V. dahliae at the later induction stage, pathogen localizing in the interior of root tissue. We identified 71 known and 378 novel miRNAs from six libraries of the pathogen-induced and the control sRNAs. Combined with degradome and sRNA sequencing, 178 corresponding miRNA target genes were identified, in which 40 target genes from differentially expressed miRNAs were primarily associated with oxidation-reduction and stress responses. More importantly, we characterized the cotton miR477-CBP60A module in the later response of the plant to V. dahliae infection. A β-glucuronidase fusion reporter and cleavage site analysis showed that ghr-miR477 directly cleaved the messenger RNA of GhCBP60A in the posttranscriptional process. The ghr-miR477-silencing decreased plant resistance to this fungus, while the knockdown of GhCBP60A increased plant resistance, which regulated GhICS1 expression to determine salicylic acid level. Our data documented that numerous later-inducible miRNAs in the plant response to V. dahliae, suggesting that these miRNAs play important roles in plant resistance to vascular disease.