Cloning and Characterization of A CC-NBS-LRR Gene in Upland Cotton

A pair of degenerating primers was designed according to the conserved regions of nucleotide binding site,and several ESTs with conserved NBS domain were isolated from cotton through RT-PCR.The full length of one EST and its 5′ flanking sequence was acquired by RACE and TAIL PCR methods.This gene was designated as GHNBS.The entire coding region is 2 583 bp and encodes a polypeptide of 861 amino acids with 28% homology to an R gene of Arabidopsis deposited in the GenBank.The alignment of GHNBS and several other NBS-LRR proteins from Arabidopsis showed that they have a relatively low homology besides the conserved domains.Southern hybridization and database search demonstrated that GHNBS genes in plants are in low copies.Through semi quantitative RT-PCR,the GHNBS expressed in the root and leaf than that in floral bud,petal and phloem is higher.In addition,the expression in xylem was not detected.