title: GhMYB25-like: a key factor in early cotton fibre development.
abstract: MYB 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 (-3days post-anthesis, dpa), increasing in expression in 0-dpa ovules, primarily in those epidermal cells expanding into fibres, and then in elongating fibres at +3dpa, 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 fibre-expressed 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.
authors.affiliation: CSIRO Plant Industry, PO Box 1600, Canberra ACT 2601, Australia.
authors.forename: Sally-Ann
authors.initials: SA
authors.lastname: Walford
authors.forename: Yingru
authors.initials: Y
authors.lastname: Wu
authors.forename: Danny J
authors.initials: DJ
authors.lastname: Llewellyn
authors.forename: Elizabeth S
authors.initials: ES
authors.lastname: Dennis
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D032561:Cotton Fiber; D018744:DNA, Plant / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D003368:Gossypium / Q000235:genetics* / Q000378:metabolism; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D056771:Ovule / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D019441:Plant Epidermis / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D034622:RNA Interference; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D014157:Transcription Factors