形態学的特徴とSSRマーカーに基づくL. var. (Franch.) Rehder (Lamiaceae)の繁殖戦略に関する研究

Studies on reproductive strategies of L. var. (Franch.) Rehder (Lamiaceae) based on morphological characteristics and SSR markers.

• Xiaohan Sun
• Feng Wang
• Rong Cui
• Xiao Liu
• Xiangxiang Li
• Jibin Dong
• Lu Sun
• Siqi Qin
• Renqing Wang
• Peiming Zheng
• Hui Wang

抄録

L. var. (Franch.) Rehder (Lamiaceae)は土壌や水の保全に重要な樹種であるが，その繁殖生態は未だ解明されていない。本研究では，本種の繁殖形質を調査するために，本種の表現学的特徴，形態学的特徴（花形，花蜜生産量，花粉生存率，スティグマ受容性），交尾システムを初めて系統的に明らかにした。本研究では，本種の交配系を初めて明らかにした。生化学的手法を用いて、花粉生存率と各開花段階でのスティグマ受容性を測定した。最後に，SSRマーカーを用いた遺伝学的解析により交配系を明らかにし，外交指数と花粉-卵子比を算出して解析を行った。また，本種では，自家受精を促進するホモガミー性や葯-スティグマ間距離の短さなどのメカニズムも確認された。自己受精と外交特性の共存から、外交混交系が優勢であることが明らかになった（外交率、=95%）。本研究で得られた科学的情報は、繁殖の観点から本種の保全に貢献する可能性がある。

L. var. (Franch.) Rehder (Lamiaceae) is an important tree species for soil and water conservation, yet the reproductive ecology of this species remains to be elucidated. To investigate the reproductive traits of var. , the phenology, morphological characteristics (a suite of characters was assessed: floral morphology, nectar production, pollen viability, and stigma receptivity) and mating system of this species were systematically revealed for the first time in this study. Phenological observations, morphological measurements, and nectar production analysis were conducted during anthesis. Pollen viability and stigma receptivity at different flowering stages were measured by biochemical methods. Finally, genetic analysis based on SSR markers was used to reveal the mating system; outcrossing index and pollen-ovule ratio were also calculated to help analysis. var. showed several obvious characteristics of outcrossing, such as abundant and attractive flowers, secreting nectar, and emitting scent. In addition, mechanisms such as homogamy and a short anther-stigma distance that can promote self-fertilization were also identified in this species. The coexistence of selfing and outcrossing characteristics demonstrates a predominantly outcrossed mixed mating system (outcrossing rate,  = 95%). The scientific information provided by this study may contribute to conservation of var. from a reproductive perspective.

© 2020 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.