Qh. Pan et al., IDENTIFICATION OF A NEW BLAST RESISTANCE GENE IN THE INDICA RICE CULTIVAR KASALATH USING JAPANESE DIFFERENTIAL CULTIVARS AND ISOZYME MARKERS, Phytopathology, 86(10), 1996, pp. 1071-1075
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 i
ndica rice cultivar Kasalath. 'Kasalath' was crossed with 9 of 12 Japa
nese differential cultivars, each carrying a single resistance gene at
one of seven known loci. Allelism tests were performed in the F-2 pop
ulations with rice blast races. The resistance of 'Kasalath' was contr
olled by two dominant genes at different loci. The two resistance gene
s 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 allel
e of the Pi-z locus. For the gene detected at the Pi-z locus, an allel
ism 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 P
i-z(t) gene. To determine the location of the other gene, a linkage te
st using isozyme markers was performed with an F-2 population segregat
ing 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 aminope
ptidase, 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 Pi
8.