Hao Feng, Xin Li, Chaojun Zhang, Ji Liu, Tao Wang, Xueyan Zhang, and Jiangli Dong. GhHUB2, a ubiquitin ligase, is involved in cotton fiber development via the ubiquitin–26S proteasome pathway. Journal of Experimental Botany. DOI: 10.1093/jxb/ery269
发布日期:2019-11-11 浏览次数:  信息来源:生物学院

GhHUB2, a ubiquitin ligase, is involved in cotton fiber development via the ubiquitin–26S proteasome pathway

Hao Feng, Xin Li, Hong Chen, Jie Deng, Chaojun Zhang, Ji Liu, Tao Wang, Xueyan Zhang, and Jiangli Dong

 

Journal of Experimental Botany

DOI: 10.1093/jxb/ery269

 

Abstract

Cotton fibers, which are extremely elongated single cells of epidermal seed trichomes and have highly thickened cell walls, constitute the most important natural textile material worldwide. However, the regulation of fiber development is not well understood. Here, we report that GhHUB2, a functional homolog of AtHUB2, controls fiber elongation and secondary cell wall (SCW) deposition. GhHUB2 is ubiquitously expressed, including within fibers. Overexpression of GhHUB2 in cotton increased fiber length and SCW thickness, while RNAi knockdown of GhHUB2 resulted in shortened fibers and thinner cell walls. We found that GhHUB2 interacted with GhKNL1, a transcriptional repressor predominantly expressed in developing fibers, and that GhHUB2 ubiquitinated and degraded GhKNL1 via the ubiquitin-26S proteasome pathway. GhHUB2 negatively regulated GhKNL1 protein levels and lead to the disinhibition of genes such as GhXTH1, Gh1,3-β-G, GhCesA4, GhAGP4, GhCTL1, and GhCOBL4, thus promoting fiber elongation and enhancing SCW biosynthesis. We found that GhREV-08, a transcription factor that participates in SCW deposition and auxin signaling pathway, was a direct target of GhKNL1. In conclusion, our study uncovers a novel function of HUB2 in plants in addition to its monoubiquitination of H2B. Moreover, we provide evidence for control of the fiber development by the ubiquitin–26S proteasome pathway.

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