QTL analysis and mapping of pi21, a recessive gene for field resistance to rice blast in Japanese upland rice |
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Authors: | S Fukuoka K Okuno |
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Institution: | (1) Department of Genetic Resources I, National Institute of Agrobiological Resources, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602 Japan e-mail: fukusan@abr.affrc.go.jp, Present address: K. Okuno, Department of Low-Temperature Sciences, Hokkaido National Agricultural Experiment Station, Hitsujigaoka 1,Toyohira, Sapporo, Hokkaido, 062-0045 Japan, JP |
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Abstract: | Field resistance is defined as the resistance that allows effective control of a parasite under natural field conditions and
is durable when exposed to new races of that parasite. To identify the genes for field resistance to rice blast, quantitative
trait loci (QTLs) conferring field resistance to rice blast in Japanese upland rice were detected and mapped using RFLP and
SSR markers. QTL analysis was carried out in F4 progeny lines from the cross between Nipponbare (moderately susceptible, lowland) and Owarihatamochi (resistant, upland).
Two QTLs were detected on chromosome 4 and one QTL was detected on each of chromosomes 9 and 12. The phenotypic variation
explained by each QTL ranged from 7.9 to 45.7% and the four QTLs explained 66.3% of the total phenotypic variation. Backcrossed
progeny lines were developed to transfer the QTL with largest effect using the susceptible cultivar Aichiasahi as a recurrent
parent. Among 82 F3 lines derived from the backcross, resistance segregated in the expected ratio of resistant 1 : heterozygous 2 : susceptible
1. The average score for blast resistance measured in the field was 4.2 ± 0.67, 7.5 ± 0.51and 8.2 ± 0.66, for resistant, heterozygous
and susceptible groups, respectively. The resistance gene, designated pi21, was mapped on chromosome 4 as a single recessive gene between RFLP marker loci G271 and G317 at a distance of 5.0 cM and 8.5 cM, respectively. The relationship to previously reported major genes and QTLs conferring
resistance to blasts, and the significance of marker-assisted selection to improve field resistance, are discussed.
Received: 8 June 2000 / Accepted: 24 November 2000 |
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Keywords: | Disease resistance Field resistance Rice (Oryza sativa L ) Rice blast (Pyricularia grisea Sacc ) |
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