Isolation, characterization and genetic diversity of NBS-LRR class disease-resistant gene analogs in multiple virus resistant line of chilli (Capsicum annuum L.)

Viruses are serious threat to chilli crop production worldwide. Resistance screening against several viruses resulted in identifying a multiple virus resistant genotype 'IHR 2451'. Degenerate primers based on the conserved regions between P-Loop and GLPL of Resistance genes (R-genes) were used to amplify nucleotide binding sites (NBS)-encoding regions from genotype 'IHR 2451'. Alignment of deduced amino acid sequences and phylogenetic analyses of isolated sequences distinguished into two groups representing toll interleukin-1 receptor (TIR) and non-TIR, and different families within the group confirming the hypotheses that dicots have both the types of NBS-LRR genes. The alignment of deduced amino acid sequences revealed conservation of subdomains P-loop, RNBS-A, kinase2, RNBS-B, and GLPL. The distinctive five RGAs showing specific conserved motifs were subjected to BLASTp and indicated high homology at deduced amino acid level with R genes identified such as Pvr9 gene for potyvirus resistance, putative late blight resistance protein homolog R1B-23 and other disease resistance genes suggesting high correlation with resistance to different pathogens. These pepper RGAs could be regarded as candidate sequences of resistant genes for marker development.