Registration of a mapping population derived from a U.S.‐adapted Calrose‐type rice variety ‘M‐202’ and a widely used Indica restorer rice variety ‘Minghui 63’

Abstract

Rice ( Oryza sativa L.) blast (caused by Magnaporthe oryzae ) is one of the most devastating rice diseases worldwide, and with the ever‐present risk of race shifts, genetic resistance to blast is constantly in peril. To facilitate genetic improvements of rice cultivars, a mapping population derived from the cross of a U.S.‐adapted Calrose‐type rice variety, ‘M‐202’, to one of the most widely used restorer rice varieties, ‘Minghui 63’ was made. This temperate japonica × indica population has been used to identify resistance genes to rice blast and genes involved in rice productivity. Namely, eight blast‐resistance quantitative trait loci (QTLs) were contributed by Minghui 63 and two QTLs by M‐202. Screening of the 254 lines in the M‐202 × Minghui 63 F ₆ recombinant inbred line (RIL; Reg. no. MP‐18 MSL 560775 MAP) population with 13 blast races revealed that ≥80% of the lines tested had moderate resistance or better to eight of the races. For the remaining five races, 76% of the RILs were moderately resistant or better to IH1, 59% to IE‐1k, 54% to IB1, 53% to IA45, and 52% to IB45. Most of the RILs are classified as medium grain, and >77% of the lines have very low chalk, in the range of ≤5% chalkiness. Two hundred two of the 248 RILs tested for plant type had a plant type score of ≤2, representing a desirable erect growth habit. The M‐202 × Minghui 63 RIL population can serve as a source for identifying novel blast‐resistance genes and providing germplasm lines with reduced chalkiness, desirable agronomic traits, and blast resistance for breeding programs.