VIEW ARTICLE

Genetics

Identification of a New Blast Resistance Gene in the indica Rice Cultivar Kasalath Using Japanese Differential Cultivars and Isozyme Markers. Qinghua Pan, Faculty of Agriculture, Kyoto University, Kyoto 606-01, Japan; Ling Wang, Hiroshi Ikehashi, and Takatoshi Tanisaka. Faculty of Agriculture, Kyoto University, Kyoto 606-01, Japan. Phytopathology 86:1071-1075. Accepted for publication 15 July 1996. Copyright 1996 The American Phytopathological Society. DOI: 10.1094/Phyto-86-1071.

Rice blast is one of the most destructive diseases of rice. This study was undertaken to identify the rice blast resistance gene(s) in the indica rice cultivar Kasalath. �Kasalath� was crossed with 9 of 12 Japanese differential cultivars, each carrying a single resistance gene at one of seven known loci. Allelism tests were performed in the F₂ populations with rice blast races. The resistance of �Kasalath� was controlled by two dominant genes at different loci. The two resistance genes were nonallelic to the nine known resistance genes at six loci, Pi-a, Pi-i, Pi-k, Pi-ta, Pi-b, and Pi-t, and one of the genes was an allele of the Pi-z locus. For the gene detected at the Pi-z locus, an allelism test was performed using race 433.5, which is virulent to Pi-z^t but avirulent to Pi-z. The results indicated that �Kasalath� has the Pi-z^t gene. To determine the location of the other gene, a linkage test using isozyme markers was performed with an F₂ population segregating 3:1 (resistant/susceptible) when tested against race 477.1, which is virulent to Pi-z^t. This gene was linked to Amp-3 (leucine aminopeptidase, EC 3.4.11.1) and Pgi-2 (phosphoglucose isomerase, EC 5.3.1.9) genes on chromosome 6 with recombination values of 37.6% � 3.0% and 27.3% � 2.7%, respectively. This gene was, therefore, designated Pi8.