Indian Society of Genetics & Plant Breeding

Identification and validation of rice blast resistance genes in Indian rice germplasm

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Blast disease caused by Magnaporthe oryzae is a major
constraint in rice production. Identification of new donors
for blast resistance is a pre-requisite for effective utilization
of diverse germplasm for marker assisted incorporation of
blast resistance into improved varieties. Therefore, in the
present study, a set of 100 diverse rice germplasm
accessions were evaluated for 11 blast resistance genes
namely Pikm, Pik, Pikh, Pi1, Pi5, Pi54, Pib, Piz5, Piz, Pi9 and
Pish, both at genotypic and phenotypic level. Genotyping
with gene based/ gene linked markers could identify six
genotypes from the germplasm possessing as many as six
resistance specific alleles. A total of 34 and 67 germplasm
lines were found to possess resistance alleles for two genes,
Pikm and Pik, respectively. Phenotypic validation using
artificial inoculation in the germplasm was carried out with
4 diverse isolates under controlled conditions. The
congruence between marker genotype and disease
phenotype on a set of monogenic lines for blast resistance
in the LTH background was used to compute Disease
Resistance Index (DRI) in the germplasm. Cumulative DRI
for each genotype was computed over all the marker loci.
The genotypes Heibao, Kalinga-I, Vijetha, Anjali, Bhaubhog,
Sada Kaijam, Kala Jeera had high cumulative resistance
score. Allelic Cumulative Disease Resistance Index (ACDRI),
a measure for comparing the effectiveness of markers was
calculated and markers linked to Pikm, Pik, Piz5, Pi1 were
found to possess higher accuracy and better correlation
with expected patterns of resistance under artificial
inoculation. Based on disease resistance index, 25
germplasm accessions were found carrying blast resistance
specific alleles at different loci and were fully validated for
disease phenotype, which are valuable in breeding for
resistance, allele mining and functional genomics studies.

Keywords: Rice, blast disease, germplasm characterization, resistance genes, gene specific markers


Year: 2014
Volume: 74
Issue: 3
Article DOI: 10.5958/0975-6906.2014.00846.3
Print ISSN: 0019-5200
Online ISSN: 0975-6906


H. Rajashekara,U. D. Singh info_circle
R. Rathour info_circle
T. R. Sharma info_circle

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