Ghr-miR166b-GhHB14 Pair With GhDLO1 Partner Mediates Cotton Plant Defence Against Verticillium dahliae

In plants, the class III homeodomain-leucine zipper (HD-ZIP III) transcription factors regulate a broad range of developmental processes. However, less research on HD-ZIP IIIs has been done on Verticillium wilt, which is a devastating disease of cotton production worldwide. Here, we report that a cotton HD-ZIP III (GhHB14) targeted by ghr-miR166b participates in plant resistance to Verticillium wilt. According to degradome data, RACE sequencing and in vivo fluorescent light assay, ghr-miR166b can target GhHB14 mRNA to directly cleave it at nucleotide position 586, suggesting that GhHB14 expression is mediated by a post-transcriptional process. Yeast two-hybrid and bimolecular fluorescence complementation analyses showed that GhHB14 can interact with GhDLO1 in cells. Plants silenced for ghr-miR166b showed significantly higher susceptibility to Verticillium dahliae infection compared to the control, while GhHB14- and GhDLO1-silenced plants exhibited significantly higher resistance. These results suggested that ghr-miR166b is a positive regulator in plant resistance against Verticillium wilt, whereas GhHB14 and GhDLO1 are both negative regulators. Therefore, ghr-miR166b-GhHB14 coupled with GhDLO1 regulates cotton plant defence against V. dahliae.