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. Keywords : Banana, P. coffeae , resistance gene analogues, expression level African Journal of Biotechnology Vol. 12(27), pp. 4256-4268
Highlights
Pest and disease resistance genes (R-genes) comprise a large and diverse group of related sequences in plant genomes
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 Resistance gene analogues (RGAs) will be helpful for further improvement of P. coffeae resistance in banana
1 to 2% of the total coding capacity of the Arabidopsis genome is contributed by the nucleotide binding site (NBS)-leucine rich repeat (LRR) sequences, and genetic mapping studies of resistance gene analogues (RGAs) provided evidence that they co-segregated with resistance markers
Summary
Pest and disease resistance genes (R-genes) comprise a large and diverse group of related sequences in plant genomes. Genes from the NBS-LRR class condition resistance to bacterial, fungal and viral pathogens, aphid and nematode pests, have been cloned from a number of plants including Arabidopsis thaliana (Bent et al, 1994; Mindirons et al, 1994; Grant et al, 1995), flax (Lawrence et al, 1995), tobacco (Whitham et al, 1994), tomato (Milligan et al, 1998) and rice (Yoshimura et al, 1998). Aarts et al (1998) reported that 1 to 2% of the total coding capacity of the Arabidopsis genome is contributed by the NBS-LRR sequences, and genetic mapping studies of resistance gene analogues (RGAs) provided evidence that they co-segregated with resistance markers. The RGA fragments were used as molecular markers for tagging the disease resistance loci in A. thaliana (Aarts et al, 1998), wheat (Chen et al, 1998), cocoa (Lanaud et al, 2004), etc
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