Isolation of genes preferentially expressed in cotton fibers by cDNA filter arrays and RT-PCR

Abstract

Cotton fibers are single-cell trichomes derived from the outer integument cells of ovules. Recent studies showed that the rapid elongation of fibers was coordinated with the expression of a subset of fiber-specific genes. Here we report the use of filter arrays of cDNAs to identify genes preferentially expressed in cotton fibers. An array of 1536 clones was hybridized with cDNA probes prepared from wild type (fiber-containing) and fl mutant (naked) ovules at 5 days post-anthesis (DPA), respectively. Subsequent RT-PCR analyses of 14 genes identified ten that were highly transcribed in cotton fibers. Among them, an RD22-like protein ( GhRDL), a putative acyltransferase ( GhACY), a Fiddlehead homolog ( GhFDH), a serine carboxypeptidase-like protein ( GhSCP), two tubulin components ( GhTUA6 and GhTUB1) and the previously reported gene encoding fiber protein E6, showed a fiber-enriched expression pattern. The other three genes, including an actin ( GhACT), a putative cellulose synthase catalytic subunit ( GhCesA-5) and a putative 24-sterol- C-methyltransferase ( GhSMT), were actively transcribed in fibers during the elongation stage, but their transcripts were also clearly present in other tissues. The possible roles of these proteins in cotton fiber development and growth are discussed.