Distribution ofHwc2-1, a causal gene of a hybrid weakness, in the World Rice Core collection and the Japanese Rice mini Core collection: its implications for varietal differentiation and artificial selection.
A pair of complementary genes,Hwc1-1atHWC1locus andHwc2-1atHWC2locus, cause a weakness phenomenon in rice. For this study, we performed haplotype analysis around theHWC2locus in two core collections comprising 119 accessions. We also examined reactions to phenol andXanthomonas oryzaepv.oryzae(Xoo) Japanese race I. To elucidate the genetic relations among all accessions, we analyzed their banding patterns of 40 Indel markers covering the rice genome. The classification by Indel markers was almost consistent with that using 4,357 SNPs. The testcross withHwc1-1carrier indicated that 37 accessions carriedHwc2-1allele, whereas 82 carriedhwc2-2allele. Strong association betweenHWC2andPhgenes was observed. Based on 14 DNA markers aroundHWC2locus andPhgenotype, the 119 accessions were divided into 50 haplotypes. To examine theHWC2candidate chromosomal region specifically, the 'haplotype group' characterized by the six DNA markers closely linked withHWC2were analyzed.Hwc2-1carriers had the same haplotype group. Somehwc2-2haplotype groups were associated with resistance against theXoorace. The relation between varietal differentiation and haplotypes around theHWC2locus was discussed, along with its breeding significance.
Faculty of Agriculture, Kagoshima University , 1-21-24 Korimoto, Kagoshima, Kagoshima 890-0065 , Japan.
Katsuyuki
K
Ichitani
Institute of Gene Research, Kagoshima University , 1-21-24 Korimoto, Kagoshima, Kagoshima 890-0065 , Japan.
Satoru
S
Taura
Faculty of Agriculture, Kagoshima University , 1-21-24 Korimoto, Kagoshima, Kagoshima 890-0065 , Japan.
Muneharu
M
Sato
College of Agriculture, Ibaraki University , 3-21-1 Chuo, Ami, Ibaraki 300-0393 , Japan.
Tsutomu
T
Kuboyama
DNA marker; Oryza sativa L.; bacterial blight resistance; haplotype; hybrid weakness; phenol reaction; varietal differentiation