Induction of useful variability for pericarp colour and bacterial blight resistance in rice (Oryza sativa L.) cv. PAU 201 through EMS based mutagenesis

PAU 201, a high yielding variety of rice released by Punjab Agricultural University in 2007, was withdrawn from cultivation in the year 2010 mainly due to its red coloured pericarp. It also became susceptible to a new pathotype (PbXo-8) of bacterial blight (BB) pathogen. To improve these specific defects, PAU 201 was mutagenized with ethyl methane sulphonate in different concentrations of 0.6, 0.8 and 1.0% in water (v/v). A total of 841 M₁ single panicles were harvested and advanced to M₄ generation following selfing and selection for white pericarp colour in each generation. A set of promising 68 M₄ progenies was also screened for BB resistance and one putative mutant possessing white pericarp colour as well as BB resistance (designated as RYT 3207) was identified. On further evaluation, RYT 3207 was found to be resistant to all the ten pathotypes of BB pathogen prevalent in the Punjab state and it yielded at par with the PAU 201 in multi-location trials during 2011 to 2013. Molecular marker analysis showed presence of xa13 locus in RYT 3207. The acquired resistance to all the ten pathotypes in RYT 3207, compared to nine pathotypes in PAU 201, could be due to modified function of xa13 gene. The new genotype RYT 3207 is a mutagenized version of the high yielding rice cultivar PAU 201 possessing white pericarp and enhanced resistance to bacterial blight.