Cloning and characterization of NBS-LRR resistance gene analogues of Musa spp. and their expression profiling studies against Pratylenchus coffeae.

Abstract

Resistance gene analogues (RGAs) were isolated from two banana cultivars viz., Karthobiumtham and Rose using degernate primers designed from the conserved motifs of different plant resistance genes. A total of 40 sequences were hit with various R genes, of which 20 sequences were having uninterrupted open reading frame (ORFs). Based on the conserved domains like P loop, internal kinase 2, kinase 3a and hydrophobic domain motifs of the deduced amino acid sequences were grouped as NBS-LRR class of resistant genes. The phylogentic analysis of RGAs showed that all the Musa RGAs are grouped under non-TIR branch and grouped into six distinct Musa RGA cluster. To investigate the expression profile of the RGAs, specific primers were designed for one representative RGA from each RGA cluster and it was found that C1 and C5 were induced upon root lesion nematode infection in the resistant (cv. Karthobiumtham) and not in susceptible (cv.Nendran) cultivar. C6 was expressed only in resistant cultivar not in susceptible one. But there was no change in the expression of C2 and C3 in both resistant and susceptible cultivars. These results indicate that in depth study on C1, and C5 RGAs will be helpful for further improvement of P. coffeae resistance in banana.