“Resistance gene analogue for disease resistance breeding”

UNIVERSITY OF AGRICULTURAL SCIENCES, BANGALORE

DEPARTMENT OF GENETICS AND PLANT BREEDING

SEMINAR – GPB 681 (0+1)

“Resistance gene analogue for disease resistance breeding”

Plants are susceptible to numerous biotic stresses during their life cycle. They have developed effective mechanisms mediated by Resistance genes (R-genes) which activate strong defense response. R-genes are very valuable resources for better understanding of plant defense mechanism and to develop disease resistant varieties or hybrids.

Resistant Gene Analogues (RGA) in plants are large class of potential R-genes which have conserved domains and motifs related to the Nucleotide binding site-Leucine rich repeats (NBS-LRR), Receptor like kinases (RLKs), Receptor like proteins (RLPs) with their structural features. These conserved motifs of R-gene encoded proteins are facilitating the scientists to fish out new resistance gene over species and genera. These sequences are used as probes to identify similar sequences in other plant, variety or species.

Molecular analysis of twenty-six different green gram genotypes using RGA marker CYR1 linked to YMV resistance produced desired amplicon in seven genotypes which have yellow mosaic virus resistance gene and the marker was an efficient and ubiquitous for genotyping of YMV reaction. OBGG 2013-20 was an YMV resistant and high yielding line which can be used as YMV donor or can be released as a variety.

A study was carried on the cloning of RGAs from finger millet (Eleusine coracana) to identify functional disease resistance genes. Comparison of finger millet RGA to sequences available in NCBI database revealed that it was most similar to NBS-LRR proteins from rice. The greatest similarity was shown with RPS2-like disease resistance protein of Oryza sativa japonica group. Finger millet RGA had a tryptophan residue (W) in the end of kinase 2 motif which is indicative of the non-TIR sub-class of R-genes, the prominent class of R-genes.

RGAs are an efficient tool in identifying and isolating the disease resistant genes and have got efficiency in building durable resistance. Knowledge on a clear, functional mechanism of plant-microbe interaction and downstream pathways of disease resistant genes is moderate. The new genomic, high throughput approaches like Next Generation Sequencing (NGS) and other techniques, can pave the way for a better understanding of resistance mechanism in plants to pathogens. Comprehensive information and knowledge on RGA and genomic R-loci architecture will help to develop multiple-disease resistance varieties or hybrids.

References:

1. JACOB, J., 2017, Cloning of a Non-TIR NBS LRR type resistance gene analogue (RGA) from finger millet. Int. J. Agric. Innov. Res., 6(3): 529-532.

2. KABI, M., DAS, T. R., BAISAKH, B. AND SWAIN, D., 2017, Resistant gene analogous marker assisted selection of yellow mosaic virus resistant genotypes in greengram (Vigna radiata). Int. J. Curr. Microbiol. App. Sci., 6: 3247-3252.

3. REDDY, A. C. AND NARESH, P., 2018, The crucial role of R-genes/RGAs in host-microbial interactions and plant immunity. Res. J. Biotechnol., 13(4): 76-95.

4. SEKHWAL, M. K., LI, P., LAM, I., WANG, X., CLOUTIER, S. AND YOU, F. M., 2015, Disease resistance gene analogues (RGAs) in plants. Int. J. Mol. Sci., 16(8): 19248-19290.