2006 Fiscal Year Final Research Report Summary
Molecular population genetics study on four Japanese oaks for maintaining them as genetic resources
| Project/Area Number |
16380104
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
林学・森林工学
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| Research Institution | Ehime University |
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Principal Investigator |
HARADA Ko Ehime University, Faculty of Agriculture, Professor, 農学部, 教授 (40150396)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Quercus mongolica var. crispula / metionine synthase / EST / adaptive evolution / natural selection / cline / glacial age / phenology |
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| Research Abstract |
Oaks are important genetic resources in Japan, especially Quercus mongolica var. crispula and related species. We have investigated genetic variation of cpDNA and found Japanese oaks are divided into two groups in southern and northern part of Japan bordering at the Itoigawa-Shizuoka tectonic Line. We further investigated additional samples from China (Liaoning Province, Harbin), Korea, Russia (Sakhalin and East coast) and showed the northern and the southern populations had respectively migrated from different land bridges in the north (Sakahalin) and the south (Korean Peninsula) during the last glacial age about twenty thousand years ago. These populations are expected to have experienced different adaptive process, i. e., cold and worm climate, respectively. We designed experimental plan to detect adaptive change at DNA level besed on this knowledge. We subcloned a part of methionine synthase gene and six EST markers on 71 individuals collected from 16 populations over Japanese Archipelago. We found 20 substitutions in coding regions including 9 nonsynoymous and 11 synonymous substitutions. For the exon 2 and exon 3 regions, the value of πa/πs exceeded 1 (= 2.48) showing evidence of natural selection. We further investigated the frequency of 5 SNPs found in the exon 2 and 3 using 222 samples collected from 19 populations, and found significant latitudinal cline in three of them. One of the six EST markers (clone 58, auxin-repressed protein) also showed significant latitudinal cline. With additional analysis we showed evidence of adaptive change in these SNPs in the northern populations.
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