Electronic Journal of Plant Breeding (Jul 2010)
Characterization of Resistance Gene Analog Polymorphisms in sugarcane cultivars with varying levels of red rot resistance
Abstract
Resistance Gene Analog (RGA) strategy is being exploited perfectly for the identification, tagging and mapping of majorgenes or Quantitative Trait Loci for disease resistance. About 29 RGA primers designed from the conserved domains ofresistance proteins, were used to analyse the genetic diversity among the 40 sugarcane cultivars that vary in their resistanceto red rot disease. The genetic similarity values ranged from 58.4 - 90% with the mean genetic similarity of 74.2%. Clusteranalysis resulted in a dendrogram with 3 major clusters and a clear distinction of resistant and susceptible varieties wasobserved. A total of 25 specific fragments amplified by 14 primers were identified to be associated with resistance and 8specific fragments amplified by 8 primers were associated with susceptibility. The primers RGA – 137, RGA 396, RGA-231 and RGA-118 amplified maximum number of resistant or susceptible specific fragments (3). Amplification of the red rotresistant variety Bo 91 and the red rot susceptible variety CoC 671 with the twenty nine RGA primers, followed bysequencing and homology analysis revealed significant homologies with the RGA’s of rice, maize and sugarcane. TheseRGA’s that were found to be associated with red rot resistant/ susceptible varieties are a valuable source of markers that canbe tested for screening red rot resistance in breeding programs
