GhMYB25‐like: a key factor in early cotton fibre development

Abstract

SUMMARYMYB transcription factors have been implicated in regulation of the development of ovule epidermal cells into the elongated seed fibres of cotton. An R2R3 MYB, GhMYB25-like, identified from its reduced expression in a fibreless mutant of cotton (Xu142 fl), is here shown to play a key role in the very early stages of fibre cell differentiation. A GhMYB25-like promoter-GUS construct was expressed predominantly in the epidermal layers of cotton ovules before anthesis ()3 days post-anthesis, dpa), increasing in expression in 0-dpa ovules, primarily in those epidermal cells expanding into fibres, and then in elongating fibres at +3 dpa, declining thereafter. This was consistent with GhMYB25-like transcript abundance during fibre development. RNA interference suppression of GhMYB25-like resulted in cotton plants with fibreless seeds, but normal trichomes elsewhere, phenocopying the Xu142 fl mutant. Like Xu142 fl these plants had reduced expression of the fibreexpressed MYBs, GhMYB25 and GhMYB109, indicating that GhMYB25-like is upstream from those MYBs. This hierarchy was supported by the absence of any change in transcript level of GhMYB25-like in GhMYB25-and GhMYB109-silenced transgenic lines. Transgenic cotton with an additional copy of the native gene had elevated expression of GhMYB25-like in ovules, but no obvious increase in fibre initials, suggesting that there may be other factors that interact with GhMYB25-like to differentiate epidermal cells into fibre cells.

Sequencing of allotetraploid cotton (Gossypium hirsutum L. acc. TM-1) provides a resource for fiber improvement

“…One group of GhMML genes was downregulated in three natural fiberless mutants (Fig. 3c,d), which resembled the fiberless seeds produced in GhMYB25-like RNA interference-suppressing lines 37 , but trichomes developed normally elsewhere. They are different from the GL1-like GhMYB2 (ref.…”

“…Cotton fiber biology and domestication MYB-domain transcription factors are important for cotton fiber and leaf trichome development [36][37][38] . Among the ten MYB MIXTA-like (GhMML) homoeologs in allotetraploid cotton ( Supplementary Fig.…”

The Cotton Transcription Factor TCP14 Functions in Auxin-Mediated Epidermal Cell Differentiation and Elongation

“…Likewise, transcription factors participating in cotton fiber development have been reported by several studies. For example, a few MYB transcription factors were found to play important roles in cotton fiber initiation (Cedroni et al, 2003;Suo et al, 2003;Wang et al, 2004;Pu et al, 2008;Machado et al, 2009;Guan et al, 2011;Walford et al, 2011). In addition, it was recently reported that GbTCP (from sea-island cotton), which shares 47% protein sequence identity with GhTCP14, is involved in cotton fiber development, possibly through JA signaling (Hao et al, 2012).…”

A Fasciclin-Like Arabinogalactan Protein, GhFLA1, Is Involved in Fiber Initiation and Elongation of Cotton

“…Similarly, suppression of Suc synthase gene expression hindered fiber initiation and elongation (Ruan et al, 2003). Furthermore, GhMYB25 and GhMYB25-like regulate early fiber development (Machado et al, 2009;Walford et al, 2011). A study reported that GhAGP4 plays a role in fiber initiation and elongation of cotton, but its molecular mechanism in regulating fiber development still remains unclear (Li et al, 2010b).…”