Identification and Cloning of Genes Related to Cotton (Gossypium hirsutum L.) Fiber Development

Abstract

This study focused on cloning of known genes and establishment of a method to identify differentially expressed genes in cotton fiber for identifying more genes and studying their expression patterns with respect to the timelines in fiber development. Total RNA from six developmental stages of cotton fiber i.e 0 days after pollination (DAP), 1 DAP, 5 DAP, 10 DAP, 15 DAP and 20 DAP was extracted and reverse transcribed to cDNA for amplification, cloning and expression profiling of reported expansin, tubulin, lipid transfer protein and some uncharacterized fiber protein through RT-PCR. Apart from cloning of reported genes, identification of differentially expressed genes at 0 DAP and 10 DAP through differential display was also accomplished. Expression profile analysis showed that transcripts of expansin, tubulin were expressed from 5 DAP to 15 DAP during the rapid stage of fiber elongation. Expression of expansin occurred through all the fiber development stages, while transcripts of tubulin were high at 15 DAP as compared to 5 and 10 DAP. The transcripts of three lipid transfer protein (PFS 18A, LTP3, non-specific L TP) were expressed through out the developmental stages with their maximum expression from 5 DAP to 15 DAP. It has been concluded that maximum expression of genes was observed during the first 15 days after pollination. During the expression profiling of uncharacterized fiber proteins ycfl gene at 20 DAP (Stage 6) and 23s rRNA of chloroplast origin were also detected through out the six developmental stages of fiber development. To our knowledge it is a first report for the existence of chloroplast in developing cotton fibers and is presumed to have some strong implications in the development of fiber traits. Cloning of fiber development specific genes from the local Pakistani cultivar of Gossypium hirsutum L.var.CIM707 have not been attempted earlier. This work is likely to generate the basic information and genetic resources for improvement of local cotton cultivars through genetic engineering.