The Cotton miR477-<i>CBP60A</i> Module Participates in Plant Defense Against <i>Verticillium dahlia</i>

Abstract

Previous reports have shown that, when <i>Verticillium dahliae</i> 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 <i>V. dahliae</i> 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-<i>CBP60A</i> module in the later response of the plant to <i>V. dahliae</i> infection. A β-glucuronidase fusion reporter and cleavage site analysis showed that ghr-miR477 directly cleaved the messenger RNA of <i>GhCBP60A</i> in the posttranscriptional process. The ghr-miR477-silencing decreased plant resistance to this fungus, while the knockdown of <i>GhCBP60A</i> increased plant resistance, which regulated <i>GhICS1</i> expression to determine salicylic acid level. Our data documented that numerous later-inducible miRNAs in the plant response to <i>V. dahliae</i>, suggesting that these miRNAs play important roles in plant resistance to vascular disease.