| Project/Area Number |
14560007
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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 | Nihon University |
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Principal Investigator |
NOMURA Kazunari Nihon University, Coll.Bioresource Sci.Plant Sci.Resources, Associated Prof., 生物資源科学部, 助教授 (90139048)
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| Co-Investigator(Kenkyū-buntansha) |
IKEHASHI Hiroshi Nihon University, Coll.Bioresource Sci.Plant Sci.Resources, Prof., 生物資源科学部, 教授 (50193222)
SHISHIDO Rieko Nihon University, Coll.Bioresource Sci.Plant Sci.Resources, Lecturer, 生物資源科学部, 講師 (90307819)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥2,400,000 (Direct Cost: ¥2,400,000)
Fiscal Year 2004: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2003: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Abscisic acid / Germination / Low temperature / NCED / Raphanus sativus / Seed dormancy / 低温発芽性 / アブシジン酸合成 |
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| Research Abstract |
One of rat's tail radishes, cv.Pakki-hood (Raphanus sativus L.) introduced from northern Thailand has germinability at low temperatures. We examined several factors that are the main barrier to germination of seeds under low temperature conditions. There was no difference in the decrease of pressure to penetrate seed coat of the both cultivars after 4 days incubation at 5℃, indicating that these finding cannot explain the difference in cold sensitivity in germination. Water uptake through the seed coat in was not affected by temperature. After a lag phase of water uptake, the water content of seeds showed a further increase at 20℃. At 5℃, no further water uptake took place in seeds of Shogoin within 6 days, while the uptake of water in the seed of Pakki-hood increased slightly after 4 days of imbibition, concurrent with radicle elongation.
To identify the mechanisms involved in germination at low temperature in Pakki-hood, we cloned the gene for 9-cis-epoxycarotenoid dioxygenase (NCED). The full-length cDNA contains an open reading frame of 1791 bp, flanked by a 148-bp 3'-untranslated region and a 399-bp 5'-untranslated region. A putative TATA box was found 177 nucleotides upstream of the initiation codon. We searched for putative cis-acting motifs there and found four MYB-recognition sites. RsNCED mRNA was not accumulated during germination. The ABA content in germinating seeds decreased rapidly before elongation of roots of Pakki-hood, but it was maintained in Shogoin, suggesting that maintenance of ABA content is correlated with the inability to germinate at low temperatures.
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