J Integr Plant Biol. ›› 2022, Vol. 64 ›› Issue (1): 39-55.DOI: 10.1111/jipb.13192

• Cell and Developmental Biology • Previous Articles     Next Articles

GhKNL1 controls fiber elongation and secondary cell wall synthesis by repressing its downstream genes in cotton (Gossypium hirsutum)

Yao Wang, Yang Li , Si‐Ying Gong , Li‐Xia Qin , Xiao‐Ying Nie , Dong Liu , Yong Zheng* and Xue‐Bao Li*   

  1. Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China

    These authors contributed equally to this work.
    *Correspondences: Yong Zheng (zhengyong@mail.ccnu.edu.cn); Xue‐Bao Li (xbli@mail.ccnu.edu.cn, Dr. Li is fully responsible for the distributions of materials associated with this article)
  • Received:2021-09-29 Accepted:2021-11-16 Online:2021-11-19 Published:2022-01-01

Abstract: Cotton which produces natural fiber materials for the textile industry is one of the most important crops in the world. Class II KNOX proteins are often considered as transcription factors in regulating plant secondary cell wall (SCW) formation. However, the molecular mechanism of the KNOX transcription factor-regulated SCW synthesis in plants (especially in cotton) remains unclear in details so far. In this study, we show a cotton class II KNOX protein (GhKNL1) as a transcription repressor functioning in fiber development. The GhKNL1-silenced transgenic cotton produced longer fibers with thicker SCWs, whereas GhKNL1 dominant repression transgenic lines displayed the opposite fiber phenotype, compared with controls. Further experiments revealed that GhKNL1 could directly bind to promoters of GhCesA4-2/4-4/8-2 and GhMYB46 for modulating cellulose synthesis during fiber SCW development in cotton. On the other hand, GhKNL1 could also suppress expressions of GhEXPA2D/4A-1/4D-1/13A through binding to their promoters for regulating fiber elongation of cotton. Taken together, these data revealed GhKNL1 functions in fiber elongation and SCW formation by directly repressing expressions of its target genes related to cell elongation and cellulose synthesis. Thus, our data provide an effective clue for potentially improving fiber quality by genetic manipulation of GhKNL1 in cotton breeding.

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