Fine mapping and candidate gene analysis of hwh1 and hwh2, a set of complementary genes controlling hybrid breakdown in rice.
Hybrid breakdown (HB), a phenomenon of reduced viability or fertility accompanied with retarded growth in hybrid progenies, often arises in the offspring of intersubspecific hybrids between indica and japonica in rice. We detected HB plants in F8 recombinant inbred lines derived from the cross between an indica variety, Milyang 23, and a japonica variety, Tong 88-7. HB plants showed retarded growth, with fewer tillers and spikelets. Genetic analysis revealed that HB was controlled by the complementary action of two recessive genes, hwh1 and hwh2, originating from each of both parents, which were fine-mapped on the short arm of chromosome 2 and on the near centromere region of the long arm of chromosome 11, respectively. A comparison of the sequences of candidate genes among both parents and HB plants revealed that hwh1 encoded a putative glucose-methanol-choline oxidoreductase with one amino acid change compared to Hwh1 and that hwh2 probably encoded a putative hexose transporter with a six amino acid insertion compared to Hwh2. Investigation of the distribution of these alleles among 54 japonica and indica cultivars using candidate gene-based markers suggested that the two loci might be involved in developing reproductive barriers between two subspecies.
Jiang
Wenzhu
W
Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, South Korea.
Chu
Sang-Ho
SH
Piao
Rihua
R
Chin
Joong-Hyoun
JH
Jin
Yong-Mei
YM
Lee
Joohyun
J
Qiao
Yongli
Y
Han
Longzhi
L
Piao
Zongze
Z
Koh
Hee-Jong
HJ
D002874:Chromosome Mapping; D032461:Chromosomes, Plant; D003433:Crosses, Genetic; D017931:DNA Primers / Q000737:chemistry / Q000235:genetics; D018744:DNA, Plant; D017343:Genes, Plant / Q000235:genetics*; D008040:Genetic Linkage; D006822:Hybrid Cells; D012275:Oryza / Q000235:genetics* / Q000254:growth & development; D010446:Peptide Fragments / Q000235:genetics; D010641:Phenotype; D040641:Quantitative Trait Loci
D017931:DNA Primers; D018744:DNA, Plant; D010446:Peptide Fragments