title: Fine mapping and candidate gene analysis of hwh1 and hwh2, a set of complementary genes controlling hybrid breakdown in rice.
abstract: 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.
authors.affiliation: Department of Plant Science and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-921, South Korea.
authors.forename: Wenzhu
authors.initials: W
authors.lastname: Jiang
authors.forename: Sang-Ho
authors.initials: SH
authors.lastname: Chu
authors.forename: Rihua
authors.initials: R
authors.lastname: Piao
authors.forename: Joong-Hyoun
authors.initials: JH
authors.lastname: Chin
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Jin
authors.forename: Joohyun
authors.initials: J
authors.lastname: Lee
authors.forename: Yongli
authors.initials: Y
authors.lastname: Qiao
authors.forename: Longzhi
authors.initials: L
authors.lastname: Han
authors.forename: Zongze
authors.initials: Z
authors.lastname: Piao
authors.forename: Hee-Jong
authors.initials: HJ
authors.lastname: Koh
mesh_terms: 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
chemical_list: D017931:DNA Primers; D018744:DNA, Plant; D010446:Peptide Fragments