Relationship Between Blast Resistance Phenotypes and Resistance Gene Analogue Profiles in Rice

A total of 21 rice varieties were assayed based on RGA-PCR using six pairs of RGA primers and evaluated for leaf blast resistance in the nursery as well. Cluster analysis showed that the varieties could be classified into five groups either at the similarity threshold of 0.72 for RGA profiles or at 0.80 for leaf blast severities. Although there did not exist a complete parallel relationship between RGA-based groups and blast resistance-based groups, five out of six varieties with broad spectrum or durable resistance repeatedly fell into same group. This result suggested that application of three primer pairs, viz. RGA1 and RGA2 (both designed from the LRR region of rice Xa21 gene) and RGA3 (designed from the LRR region of tobacco N gene) contributed to better evaluation of the germplasms for their resistance responses to rice blast