Molecular cloning and characterization of disease-resistance gene candidates of the nucleotide binding site (NBS) type from Cocos nucifera L

In this study, degenerate primers were used to amplify nucleotide-binding site (NBS)-type sequences from coconut ecotypes either resistant or susceptible to lethal yellowing. Genomic DNA fragments of approximately 500-700 bp were obtained and sequenced. Phylogenetic analysis of these fragments revealed that they clustered in seven different clades. We also found that all CnRGC sequences were grouped within the non-TIR-NBS-LRR subclass of NBS-LRR genes. The expression analysis revealed changes in expression profiles in response to salicylic acid (SA) and a constitutive expression profile in plants untreated with SA. This is the first large scale analysis of NBS-type sequences in coconut palm.