Cloning of a phosphatidylinositol 4-kinase gene based on fber strength transcriptome QTL mapping in the cotton species gossypium barbadense

Abstract

Sea Island cotton (Gossypium barbadense) is highly valued for its superior fber qualities, especially fber strength. Based on a transcript-derived fragment originated from transcriptome QTL mapping, a fber strength related candidate gene of phosphatidylinositol 4-kinase cDNA, designated as GbPI4K, was frst cloned, and its expression was characterized in the secondary cell wall thickening stage of G. barbadense fbers. The ORF of GbPI4K was found to be 1926 bp in length and encoded a predicted protein of 641 amino acid residues. The putative protein contained a clear PI3/4K kinase catalytic domain and fell into the plant type II PI4K cluster in phylogenetic analysis. In this study, the expression of cotton PI4K protein was also induced in Escherichia coli BL21 (DE3) as a fused protein. Semi-quantitative RT-PCR analysis showed that the gene expressed in the root, hypocotyl and leaf of the cotton plants. Real-time RT- PCR indicated that this gene in Sea Island cotton fbers expressed 10 days longer than that in Upland cotton fbers, and the main expression difference of PI4K between Sea Island cotton and Upland cotton in fbers was located in the secondary cell wall thickening stage of the fber. Further analysis indicated that PI4K is a crucial factor in the ability of Rac proteins to regulate phospholipid signaling pathways. ©FUNPEC-RP.