Identification of blast resistance expression in rice genotypes using molecular markers (RAPD & SCAR)

Rice is the second most important cereal crop of developing countries and the staple food of about 65% of the world's population. In this endeavor, it is important to identify resistant gene(s) with the help of markers. Once a gene is tagged with a molecular marker, it can be transferred selectively into different genetic backgrounds by marker assisted selection. For this purpose, 48 elite Indian and exotic rice genotypes were evaluated for resistance to blast disease under induced epiphytotic conditions obtained in the field. The disease severity (%) and AUDPC was less than 45% and 1000, respectively, in all the resistant genotypes, while it was around 85% and higher than 2000 in the case of susceptible genotypes, respectively. Substantial variability was present among rice genotypes for resistance to Magnaporthe grisea. Ten random amplified polymorphic DNAs ( RAPD) and two sequence characterized amplified region ( SCAR) primers were used to identify blast resistant genes. Markers OPA-05, OPF-06, OPF-09, OPF-17, OPG-17, OPG-18, OPG-19, OPH-18, OPK-12, P-265-550 and P-286-350 found linked to blast resistance in most of the resistant genotypes could be considered as potent molecular markers in the selection of blast resistant genotypes. Amplification with RAPD and SCAR primers revealed a nonallelic relationship among resistant genotypes and thus, there is a good possibility of obtaining enhanced resistance through gene pyramiding.