Registration of 42 Blast Resistant Medium Grain Rice Genetic Stocks with Suitable Agronomic, Yield, Milling Yield, and Seed Characteristics

Rice blast disease caused by the filamentous ascomycete fungus Magnaporthe oryzae Cav. [Magnaporthe grisea (Herbert) Barr.] is one of the most threatening rice (Oryza sativa L.) diseases in the southern United States. Forty‐two rice blast resistant genetic stocks (Reg. No. GS‐34 to Reg. No. GS‐75, GSOR 102501 to GSOR 102542) were developed and released by the USDA‐ARS Dale Bumpers National Rice Research Center, Stuttgart, AR. The genetic stocks were developed from a cross of ‘M‐202’ (PI 494105), a medium grain cultivar of premium quality, with the blast resistant long grain rice cultivar Katy (PI 527707), followed by five generations of backcrossing to the medium grain parent M‐202. Two progenies of each of the 22 BC5F1 were genotyped with simple sequence repeat markers and evaluated with blast pathogen to verify the existence of the large blast resistance gene cluster on chromosome 12 being inherited from Katy. A total of 42 BC5F2 progenies resistant to blast were grown under field conditions during 2013 to 2014 at Stuttgart for agronomic and grain quality characterization. Agronomic traits, yield components, seed characteristics, yield, and milling quality of these lines were very similar to M‐202. The genetic stocks will be useful for rice breeders to develop new medium grain cultivars with broad spectrum blast resistance.