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bioRxiv · 10.1101/2024.09.02.610783

KAI2-dependent signaling controls vegetative reproduction in Marchantia polymorpha through activation of LOG-mediated cytokinin synthesis

Komatsu, A.·Fujibayashi, M.·Kumagai, K.·Suzuki, H.·Hata, Y.·Takebayashi, Y.·Kojima, M.·Sakakibara, H.·Kyozuka, J.
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Abstract

Marchantia polymorpha reproduces vegetatively (asexually) by producing propagules known as gemmae within gemma cups and sexually through spores. We previously reported that KARRIKIN INSENSITIVE 2 (KAI2)-dependent signaling promotes gemma cup and gemma formation. KAI2A perceives unidentified endogenous ligand(s), tentatively referred to as KAI2 ligands (KL). Perception of KL by KAI2 triggers MAX2-dependent proteolysis of MpSMXL. In this study, we identified genes working downstream of KAI2-dependent signaling in M. polymorpha. We found that KAI2-dependent signaling positively controls the expression of MpLONLEY GUY (MpLOG), encoding a cytokinin biosynthesis enzyme. Disruption of the MpLOG function decreased endogenous cytokinin levels and caused defects similar to KAI2-dependent signaling mutants. Moreover, supplying exogenous cytokinins rescued the defects of Mplog and KAI2-dependent signaling mutants, implying that cytokinins work downstream of KAI2-dependent signaling. Activation of MpLOG by KAI2-dependent signaling occurs in a highly cell-type-specific manner, leading to cell-specific induction of GEMMA CUP-ASSOCIATED MYB1 (GCAM1), the master regulator of vegetative reproduction of M. polymorpha. We propose a genetic cascade, starting from KAI2-dependent signaling, that promotes vegetative reproduction through the induction of MpLOG and GCAM1. The interaction between KAI2-dependent signaling and cytokinin in M. polymorpha provides a novel insight into the function and evolution of KAI2-dependent signaling.

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Komatsu, A., Fujibayashi, M., Kumagai, K., Suzuki, H., Hata, Y., Takebayashi, Y., Kojima, M., Sakakibara, H., Kyozuka, J.. 2024-09-02. KAI2-dependent signaling controls vegetative reproduction in Marchantia polymorpha through activation of LOG-mediated cytokinin synthesis. https://doi.org/10.1101/2024.09.02.610783

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