Development of Monogenic and Digenic Rice Lines for Blast Resistance Genes Pi-ta, Pi-kh/Pi-ks

The major blast resistance (R) genes Pi-ta, Pi-k(s), Pi-k(h) have been effectively deployed in rice (Oryza sativa L.) in the southern USA for preventing disease caused by the predominant U.S. races of Magnaporthe oryzae Cav. [=Magnaporthe grisea (Herbert) Barr.]. In the present study, the codominant single nucleotide length polymorphism DNA marker for the Pi-ta gene, and the simple sequence repeat markers, RM144 and RM224, that cosegregate with two alleles of the Pi-k gene, Pi-k(s) and Pi-k(h), were used for R identification in a F10 recombinant inbred line population. This population (Reg. no. MP-3, NSL 452303) was derived from the cross RU9101001/‘Katy’. This population composed of 235 individual lines was jointly released on 24 Apr. 2009 by the USDA–ARS and the University of Arkansas Division of Agriculture Arkansas Agriculture Experiment Station. R gene containing RIL lines were verified with standard pathogenicity assays by means of a set of differential races of M. oryzae in the USA. One hundred eighty-two pure lines were identified from the population with the Pi-ta, Pi-k(s), and Pi-k(h) genes. A total of 56 had Pi-ta and Pi-k(s), 51 lines had Pi-k(s), 27 had Pi-k(h), and 48 lines had Pi-k(h) and Pi-ta. These monogenic and digenic rice lines with the major blast R genes are expected to be useful for studying effects of each R gene singly and in combination for their epistatic interaction with yield and for introducing blast resistance with marker assisted selection.