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Molecular Mapping of the Blast Resistance Genes Pi2-1 and Pi51(t) in the Durably Resistant Rice ‘Tianjingyeshengdao’

First to eighth and eleventh to fifteenth authors: Hunan Provincial Key Laboratory of Crop Germplasm Innovation and Utilization and College of Agronomy, Hunan Agricultural University, Changsha, Hunan 410128, China; first and sixteenth authors: Department of Plant Pathology, The Ohio State University, Columbus 43210; and ninth and tenth authors: State Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.

Tianjingyeshengdao' (TY) is a rice cultivar with durable resistance to populations of Magnaporthe oryzae (the causal agent of blast) in China. To understand the genetic basis of its resistance to blast, we developed a population of recombinant inbred lines from a cross between TY and the highly susceptible ‘CO39’ for gene mapping analysis. In total, 22 quantitative trait loci (QTLs) controlling rice blast resistance were identified on chromosomes 1, 3, 4, 5, 6, 9, 11, and 12 from the evaluation of four disease parameters in both greenhouse and blast nursery conditions. Among these QTLs, 19 were contributed by TY and three by CO39. Two QTL clusters on chromosome 6 and 12 were named Pi2-1 and Pi51(t), respectively. Pi2-1 was detected under both growth chamber and natural blast nursery conditions, and explained 31.24 to 59.73% of the phenotypic variation. Pi51(t) was only detected in the natural blast nursery and explained 3.67 to 10.37% of the phenotypic variation. Our results demonstrate that the durable resistance in TY is controlled by two major and seven minor genes. Identification of the markers linked to both Pi2-1 and Pi51(t) in this study should be useful for marker-aided selection in rice breeding programs as well as for molecular cloning of the identified resistance genes.