1993 Fiscal Year Final Research Report Summary
Analysis of flower induction by Ri rolC gene and its application to plant breeding
| Project/Area Number |
04455005
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
広領域
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| Research Institution | University of Tsukuba |
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Principal Investigator |
KAMADA Hiroshi Univ.Tsukuba, Inst.Biol.Sci., Professor, 生物科学系, 教授 (00169608)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Belladonna / Ri plasmid / rolC gene / Flower induction / Transgenic plants / Field experiment / Gibberellin / Cytokinin |
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| Research Abstract |
It is well known that the rol genes on T-DNA of Ri plasmids are a main factor for hairy root disease. To clarify physiological functions of rolC gene, a chimeric gene, of which the structural rolC gene was ligated with CaMV35S promoter, was constructed and introduced into belladonna. The transgenic belladonna showed dwarfism and early flowering phenotype. Self-pollinated progenies of the transgenic plants were cultivated in a greenhouse equivalent to P1 biological containment level and the morphological and physiological characteristics were examined in the 1st and 2nd generations. The progenies were divided into 3 types. Type 1 plants had similar characteristics as those of non-transformed one, type 2 showed dwarfism and early flowering as same as those in the transformed plants and type 3 showed suppression in the growth and did not differentiate flowers. The segregation ratio of type 1, 2 and 3 was about 1 : 2 : 1, respectively. It is thought that the chimeric rolC gene delivered into belladonna functions as a dominant gene and the growth of rolC homozygous plants was suppressed by over expression of the rolC gene. These results indicate that the appropriate control of the rolC gene expression is required in its application to plant breeding.
On the other hand, qualitative and quantitative analyzes of endogenous phytohormones were carried out using type 1 and 2 belladonna described above. The contents of abscisic acid, cytokinin, and gibberellin in stems and leaves increased slightly in type 2, but no difference in the contents was observed in roots. When type 1 and 2 plants were treated with various plant growth regulators, the plants did not show early flowering which is a characteristic feature observed in plants transformed with rolC gene. These results did not coincide with the previously reported one (rolC gene encodes cytokinin glucosidase). It is required to consider another possibility on physiological function of rolC gene.
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