Reference "QTL analysis and mapping of pi21, a recessive gene for field resistance to rice blast"

Reference ID

6884

Title

QTL analysis and mapping of pi21, a recessive gene for field resistance to rice blast

Source

Theoretical and applied genetics, 2001, vol. 103, pp. 185-190

Authors (2)

Fukuoka-S

Okuno-K

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.