Relationship between inheritance of non-dormancy traits of flower buds and SVP gene in the cross of (Rhododendron oldhamii x R.kiusianum) x R. kiusianum.

Research Project

Project/Area Number	19K06036
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Review Section	Basic Section 39030:Horticultural science-related
Research Institution	University of the Ryukyus
Principal Investigator	Ureshino Kenji 琉球大学, 農学部, 教授 (10333759)
Project Period (FY)	2019-04-01 – 2022-03-31
Project Status	Completed (Fiscal Year 2021)
Budget Amount *help	¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000) Fiscal Year 2021: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2019: ¥1,690,000 (Direct Cost: ¥1,300,000、Indirect Cost: ¥390,000)
Keywords	ツツジ / 花芽非休眠性 / SVP / 花芽休眠 / 開花期間 / 平均開花日 / 非休眠性 / 不時開花性
Outline of Research at the Start	日本に自生する常緑性ツツジ種は初夏から秋にかけて花芽を形成し，花芽はその後休眠に入る．休眠打破には一定の低温遭遇期間が必要なため，開花は翌春になる．一方，台湾に自生するキンモウツツジには花芽の休眠を伴わない秋咲き性の系統がある．四季咲性の形質は，花芽の休眠性の程度が大きく関与していると考えられるが，ツツジ属において休眠に関与する遺伝子についての知見は少ない．そこで，本研究ではツツジ属植物における休眠の遺伝子レベルでの制御機構を明らかにすることを目的とする．
Outline of Final Research Achievements	To clarify the relationship between the non-dormancy of flower bud in Rhododendron oldhamii and the SVP gene,　flowering habit and the inheritance of SVP gene were investigated using BC1 seedlings from (R. oldhamii × R. kuisianum #1 )×R.kiusianum #2). In the F1 seedlings, the first flowering date was early in all the individuals, suggesting that the non-dormancy habit from R. oldhamii is dominant. In the BC1 seedlings, the first flowering day varied widely, suggesting that they were separated into non-dormant and dormant types. When the inheritance of the SVP gene in BC1 was investigated using the PCR-RFLP method, the first flowering date of the BC1 population with the SVP derived from R. oldhamii was early. From these results, the relationship between the inheritance of the SVP gene and the dormancy of flower buds was suggested.
Academic Significance and Societal Importance of the Research Achievements	ツツジの花芽における休眠性の要因を遺伝子レベルで明らかにし，休眠性の交配後代への遺伝と関連する遺伝子を明らかにすることで，育種を効率的に行う際に必要な，低休眠性系統を選抜できるマーカーの開発が可能になり，沖縄など冬季の低温量が少ない亜熱帯地域に適応したツツジ品種の効率的な作出が可能になる．