[植物演化] 蘚苔類營養繁殖與維管束植物側芽發育的調控。 20191111 Current Biology

Plasmodesmata
Nov 11, 2019
2 min read

GEMMA CUP-ASSOCIATED MYB1, an Ortholog of Axillary Meristem Regulators, Is Essential in Vegetative Reproduction in Marchantia polymorpha

Yukiko Yasui, Shigeyuki Tsukamoto, Tomomi Sugaya, Ryuichi Nishihama, Quan Wang, Hirotaka Kato, Katsuyuki T. Yamato, Hidehiro Fukaki, Tetsuro Mimura, Hiroyoshi Kubo, Klaus Theres, Takayuki Kohchi, and Kimitsune Ishizaki

Summary

A variety of plants in diverse taxa can reproduce asexually via vegetative propagation, in which clonal propagules with a new meristem(s) are generated directly from vegetative organs. A basal land plant, Marchantia polymorpha, develops clonal propagules, gemmae, on the gametophyte thallus from the basal epidermis of a specialized receptacle, the gemma cup. Here we report an R2R3-MYB transcription factor, designated GEMMA CUP-ASSOCIATED MYB1 (GCAM1), which is an essential regulator of gemma cup development in M. polymorpha. Targeted disruption of GCAM1 conferred a complete loss of gemma cup formation and gemma generation. Ectopic overexpression of GCAM1 resulted in formation of cell clumps, suggesting a function of GCAM1 in suppression of cell differentiation. Although gemma cups are a characteristic gametophyte organ for vegetative reproduction in a taxonomically restricted group of liverwort species, phylogenetic and interspecific complementation analyses support the orthologous relationship of GCAM1 to regulatory factors of axillary meristem formation, e.g., Arabidopsis REGULATOR OF AXILLARY MERISTEMS and tomato Blind, in angiosperm sporophytes. The present findings in M. polymorpha suggest an ancient acquisition of a transcriptional regulator for production of asexual propagules in the gametophyte and the use of the regulatory factor for diverse developmental programs, including axillary meristem formation, during land plant evolution.

側芽分生組織調控因子的同源基因 - 與芽杯相關的MYB1轉錄因子，在地錢Marchantia polymorpa的出芽生殖中扮演著必要的角色。

總結

在許多的分類群中，有很多植物可以經由無性的營養繁殖 - 經由營養器官直接生成一個新的分生組織，並且形成複製的個體來繁衍。早期演化出的植物中的地錢（Marchantia polymorpha）會從配子體的葉狀體上一個特化的容器 - 芽杯，地層的表皮細胞發展出複製的芽來繁殖。在此，我們報導了一個R2R3-MYB的轉錄因子，我們命名為GCAM1（芽杯相關的MYB1），是一個在Marchantia中調控芽杯發育的必要調節因子。有目標性的截斷GCAM1基因會導致芽杯生成完全喪失，並且缺乏牙的產生。而異位過度表現GCAM1會導致細胞群的生成，意味著GCAM1的功能可能是在抑制細胞的分化。雖然，芽杯是只在地錢這個特別的分類群中所特有的營養繁殖系統，系統發生以及跨物種的互補實驗分析的結果，顯示GCAM1與調控側芽分生組織生成的調控因子，例如在被子植物阿拉伯芥中的側芽分生組織調控者（REGULATOR OF AXILLARY MERISTEMS）以及蕃茄中的Blind，為同源基因。這個在Marchantia中的研究顯示，在早期就具備了在配子體調節無性繁殖的調節因子，並且在陸生植物的演化過程中，利用這個調節因子來調控不同的發育反應，包括側芽分生組織的形成。