2005 Fiscal Year Final Research Report Summary
Fine mapping of Hwc1 and Hwc2, two complementary hybrid weakness gene in rice
| Project/Area Number |
16580001
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Breeding science
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| Research Institution | College of Agriculture, Ibaraki University |
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Principal Investigator |
KUBOYAMA Tsutomu Ibaraki University, College of Agriculture, Associate Professor, 農学部, 助教授 (10260506)
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| Co-Investigator(Kenkyū-buntansha) |
MARUBASHI Wataru Meiji University, Faculty of Agriculture, Professor, 農学部, 教授 (00181826)
ICHITANI Katsuyuki Kagoshima University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (10305162)
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| Project Period (FY) |
2004 – 2005
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| Keywords | hybrid weakness / reproductive barrier / Oryza sativa / Japonica / Jamaica / mapping / complementary dominant / root growth |
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| Research Abstract |
Hybrid weakness is a reproductive barrier that is found in many plant species. In rice, the hybrid weakness caused by two complementary genes, Hwc1 and Hwc2, has been surveyed intensively. However, their gene products and the molecular mechanism that causes hybrid weakness have remained unknown. We performed linkage analyses of Hwc1, narrowed down the area of interest to 60 kb, and identified eight candidate genes. In the F_2 population, in which both Hwc1 and Hwc2 genes were segregated, plants were separable into four classes according to their respective phenotypes: severe type, semi-severe type, F_1 type, and normal type. Severe type plants show such severe symptoms that they could produce only tiny shoot-like structures; they were unable to generate roots. Genetic analyses using closely linked DNA markers of the two genes showed that the symptoms of the F_2 plants were explainable by the genotypes of Hwc1 and Hwc2. Weakness was observed in plants that have both Hwc1 and Hwc2. In Hwc1 homozygote, the symptoms worsened and severe type or semi-severe type plants appeared. Consequently, Hwc1 should have a gene dosage effect and be a semi-dominant gene. The dosage effect of Hwc2 was recognizable, but it was not so severe as that in Hwc1. These results are useful to elucidate the mechanism that causes the hybrid weakness phenomenon and the role of each causal gene in hybrid weakness.
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