Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan.
Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8577, Japan; Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan.
Curr Biol. 2023 Apr 10;33(7):1196-1210.e4. doi: 10.1016/j.cub.2023.02.022. Epub 2023 Mar 1.
In vegetative reproduction of Marchantia polymorpha (M. polymorpha), propagules, called gemmae, are formed in gemma cups. Despite its significance for survival, control of gemma and gemma cup formation by environmental cues is not well understood. We show here that the number of gemmae formed in a gemma cup is a genetic trait. Gemma formation starts from the central region of the floor of the gemma cup, proceeds to the periphery, and terminates when the appropriate number of gemmae is initiated. The MpKARRIKIN INSENSITIVE2 (MpKAI2)-dependent signaling pathway promotes gemma cup formation and gemma initiation. The number of gemmae in a cup is controlled by modulating the ON/OFF switch of the KAI2-dependent signaling. Termination of the signaling results in the accumulation of MpSMXL, a suppressor protein. In the Mpsmxl mutants, gemma initiation continues, leading to the formation of a highly increased number of gemmae in a cup. Consistent with its function, the MpKAI2-dependent signaling pathway is active in gemma cups where gemmae initiate, as well as in the notch region of the mature gemma and midrib of the ventral side of the thallus. In this work, we also show that GEMMA CUP-ASSOCIATED MYB1 works downstream of this signaling pathway to promote gemma cup formation and gemma initiation. We also found that the availability of potassium affects gemma cup formation independently from the KAI2-dependent signaling pathway in M. polymorpha. We propose that the KAI2-dependent signaling pathway functions to optimize vegetative reproduction by adapting to the environment in M. polymorpha.
在叉叶钱苔（M. polymorpha）的营养繁殖中，产生称为芽胞的繁殖体在芽胞杯中形成。尽管芽胞对于生存很重要，但环境线索对芽胞和芽胞杯形成的控制还没有得到很好的理解。我们在这里表明，芽胞杯中形成的芽胞数量是一种遗传特征。芽胞的形成从芽胞杯底部的中央区域开始，向边缘推进，当启动适当数量的芽胞时终止。MpKARRIKIN INSENSITIVE2（MpKAI2）依赖性信号通路促进芽胞杯形成和芽胞起始。杯中的芽胞数量通过调节 KAI2 依赖性信号的 ON/OFF 开关来控制。信号的终止导致 MpSMXL 的积累，MpSMXL 是一种抑制蛋白。在 Mpsmxl 突变体中，芽胞起始继续进行，导致杯中的芽胞数量极显著增加。与它的功能一致，MpKAI2 依赖性信号通路在芽胞起始的芽胞杯中以及成熟芽胞的缺口区域和腹面中肋中活跃。在这项工作中，我们还表明，GEMMA CUP-ASSOCIATED MYB1 在该信号通路的下游工作，以促进芽胞杯形成和芽胞起始。我们还发现，钾的可用性独立于 KAI2 依赖性信号通路影响芽胞杯的形成。我们提出，KAI2 依赖性信号通路通过适应 M. polymorpha 中的环境来优化营养繁殖。
