2007 Fiscal Year Final Research Report Summary
Molecular mechanisms of the generation of pigmented seeds from yellow soybean plants
| Project/Area Number |
17580003
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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 | Hirosaki University |
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Principal Investigator |
SENDA Mineo Hirosaki University, Hirosaki University, Faculty of Agriculture and Life Science, Associate Professor (30261457)
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| Project Period (FY) |
2005 – 2007
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| Keywords | yellow soybean / pigmented seeds / I gene / mutation / CHS gene / PTGS / GmIRCHS / transgenic Arabidopsis |
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| Research Abstract |
Most commercial soybean varieties have yellow seeds due to loss of pigmentation in the seed coat. The I gene inhibits pigmentation over the entire seed coat, resulting in a uniform yellow color of mature harvested seeds. We previously demonstrated that the inhibition of seed coat pigmentation by the I gene results from post-transcriptional gene silencing (PTGS) of chalcone synthase (CHS) genes. Little is known about the structure of the I gene and the mechanism by which it induces PTGS of CHS genes. In this study, we identified a candidate of the I gene, GmIRCHS, which consists of a 5'-portion of a DnaJ-like gene containing a promoter region and a perfect inverted repeat (IR) of 1.1-kb truncated CHS3 sequences (5'-ΔCHS3 and 3'-ΔCHS3). RT-PCRs indicated the existence of the read-through product from 5'-ΔCHS3 to 3'-ΔCHS3 and the dsRNA region of ΔCHS3, suggesting that dsRNA of ΔCHS3 could be transcribed from GmIRCHS and could induce PTGS of CHS genes. Moreover, the IR structure of ΔCHS3 in GmIRCHS was lost in the soybean mutants in which I was changed to i, supporting the conclusion that GmIRCHS is the I gene. Finally, to analyze the expression pattern of GmIRCHS, we constructed transgenic Arabidopsis expressing a reporter gene fusion of the GmIRCHS promoter and the β-glucronidase (GUS) gene. Intense staining was not observed in the seed coat, indicating that GmIRCHS is not specifically expressed in the seed coat tissues.
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