Resistance gene mining using NBS conserved sequences in cotton

The resistance gene analog mining of cotton using NBS conserved sequences.Primers were designed according to the sequences of conserved P-loop and transmembrane motifs.The primers were used to amplify the disease resistance gene analogs(RGAs) in cotton varieties with different resistance levels against pathogen.Several PCR products about 500 bp were obtained,and these PCR products were cloned and sequenced.Blast analysis showed that all of them,except for one,are homologous to other disease resistance gene analogues(RGAs) with the similarity more than 98%.N-J phylogenetic tree was constructed based on RGAs sequences of cotton and other resistance gene sequences sought from GenBank in NCBI.When the sequences of 15 TIR type RGAs were compared with known resistance gene(cf-5、L6、Mil-2、RPM1、PRS2、Bs2、Gpa2、I2C-1) sequences,the RGA sequences were clustered in three different subfamilies,the RGAs may further be used as molecular marker for screening of candidate disease-resistance genes in cotton.