Transcriptional Regulation and Characterization of Fusarium udum Responsive NBS-LRR Genes in Pigeonpea (Cajanus cajan (L.) Millsp.

We identified 41 pathogen responsive CcNBS-LRR genes which belonged to two major groups of NBS-LRR genes, i.e., TIR-NBS-LRR (6) and NON-TIR-NBS-LRR (35). Gene structures, motifs, cis-acting elements, and chromosomal distributions of these pathogen responsive CcNBS-LRRs were analyzed. Further, transcriptional regulation of 41 biotic stress responsive CcNBS-LRRs was recorded against Fusarium udum in a wilt resistant and a susceptible cultivar. 39 and 37 genes were differentially up-regulated in the resistant and susceptible cultivar, respectively. Two genes Cc143 and Cc150 were upregulated at all sampling periods in the resistant cultivar, whereas, in the susceptible cultivar four genes (Cc127, Cc129, Cc219, and Cc87) were constantly down-regulated and a single gene Cc255 was up-regulated at all sampling periods. The resistant cultivar also displayed rapid up-regulation (within 6 h) of the genes against F. udum. CcNBS 125, CcNBS 244, CcNBS 22, CcNBS 136, and CcNBS 143 were identified as major genes in the resistant cultivar as their relative gene expression increased by 33 folds (6 h), 31 folds (24 h), 27 folds (48 h), 25 folds (6 h), and 25(48 h) folds change, respectively, in comparison to the control. Similarly in the susceptible cultivar CcNBS 255, CcNBS 161, and CcNBS 143 were considered major gene as their relative gene expression enhanced 12 folds, 11 folds, and 11 folds, respectively, at 72 h post-inoculation. The study provided fundamental insight into the role of biotic stress responsive CcNBS-LRRs in defense responses against the wilt pathogen F. udum.