Expression Profiling Identifies Genes Expressed Early During Lint Fibre Initiation in Cotton

Abstract

Cotton fibres are a subset of single epidermal cells that elongate from the seed coat to produce the long cellulose strands or lint used for spinning into yarn. To identify genes that might regulate lint fibre initiation, expression profiles of 0 days post-anthesis (dpa) whole ovules from six reduced fibre or fibreless mutants were compared with wild-type linted cotton using cDNA microarrays. Numerous clones were differentially expressed, but when only those genes that are normally expressed in the ovule outer integument (where fibres develop) were considered, just 13 different cDNA clones were down-regulated in some or all of the mutants. These included: a Myb transcription factor (GhMyb25) similar to the Antirrhinum Myb AmMIXTA, a putative homeodomain protein (related to Arabidopsis ATML1), a cyclin D gene, some previously identified fibre-expressed structural and metabolic genes, such as lipid transfer protein, alpha-expansin and sucrose synthase, as well as some unknown genes. Laser capture microdissection and reverse transcription-PCR were used to show that both the GhMyb25 and the homeodomain gene were predominantly ovule specific and were up-regulated on the day of anthesis in fibre initials relative to adjacent non-fibre ovule epidermal cells. Their spatial and temporal expression pattern therefore coincided with the time and location of fibre initiation. Constitutive overexpression of GhMyb25 in transgenic tobacco resulted in an increase in branched long-stalked leaf trichomes. The involvement of cell cycle genes prompted DNA content measurements that indicated that fibre initials, like leaf trichomes, undergo DNA endoreduplication. Cotton fibre initiation therefore has some parallels with leaf trichome development, although the detailed molecular mechanisms are clearly different.

Toward Sequencing Cotton (Gossypium) Genomes: Figure 1.

“…Moreover, A subgenome ESTs of all functional classifications are dramatically enriched in G. hirsutum fiber , a result consistent with the production of long lint fibers in A genome species. Some ESTs have been used to develop sequence-specific markers in breeding and to construct microarrays, leading to the identification of many candidate genes involved in fiber cell initiation and elongation (Arpat et al, 2004;Lee et al, 2006;Shi et al, 2006;Wu et al, 2006;Udall et al, 2007).…”

Gene expression and metabolite profiles of cotton fiber during cell elongation and secondary cell wall synthesis

“…The transcriptomes of cotton fibers and that of the fuzzless-lintless (fl) mutant ovules were recently compared; in combination with the results obtained from in vitro ovule culture, the authors proposed that ethylene plays a major role in fiber elongation [25]. Another investigation of 0 DPA ovule transcriptomes of the wide-type and six reduced fiber or fiberless mutants showed that 13 genes were downregulated in mutants, including an MYB transcription factor (GhMyb25) and a homeodomain protein, providing information for parallels between cotton fiber initiation and leaf trichome development [26].…”

The R2R3 MYB Transcription Factor GhMYB109 Is Required for Cotton Fiber Development

“…Recent studies on cotton fiber development have been focused largely on gene expression profiles during fiber elongation and secondary cell-wall synthesis (Arpat et al 2004;Shi et al 2006;Udall et al 2006;Wu et al 2006;Yang et al 2006;Taliercio and Boykin 2007). Previous results suggested that transcription factors could play important roles in cotton fiber development.…”