Cytokinin Signaling Is Essential for Organ Formation in Marchantia polymorpha

Shiori S. Aki, Tatsuya Mikami, Satoshi Naramoto, Ryuichi Nishihama, Kimitsune Ishizaki, Mikiko Kojima, Yumiko Takebayashi, Hitoshi Sakakibara, Junko Kyozuka, Takayuki Kohchi, Masaaki Umeda

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Cytokinins are known to regulate various physiological events in plants. Cytokinin signaling is mediated by the phosphorelay system, one of the most ancient mechanisms controlling hormonal pathways in plants. The liverwort Marchantia polymorpha possesses all components necessary for cytokinin signaling; however, whether they respond to cytokinins and how the signaling is fine-tuned remain largely unknown. Here, we report cytokinin function in Marchantia development and organ formation. Our measurement of cytokinin species revealed that cis-zeatin is the most abundant cytokinin in Marchantia. We reduced the endogenous cytokinin level by overexpressing the gene for cytokinin oxidase, MpCKX, which inactivates cytokinins, and generated overexpression and knockout lines for type-A (MpRRA) and type-B (MpRRB) response regulators to manipulate the signaling. The overexpression lines of MpCKX and MpRRA, and the knockout lines of MpRRB, shared phenotypes such as inhibition of gemma cup formation, enhanced rhizoid formation and hyponastic thallus growth. Conversely, the knockout lines of MpRRA produced more gemma cups and exhibited epinastic thallus growth. MpRRA expression was elevated by cytokinin treatment and reduced by knocking out MpRRB, suggesting that MpRRA is upregulated by the MpRRB-mediated cytokinin signaling, which is antagonized by MpRRA. Our findings indicate that when plants moved onto land they already deployed the negative feedback loop of cytokinin signaling, which has an indispensable role in organogenesis.

Original languageEnglish
Pages (from-to)1842-1854
Number of pages13
JournalPlant and Cell Physiology
Volume60
Issue number8
DOIs
Publication statusPublished - 2019 Aug 1

Keywords

  • Cytokinin
  • Marchantia polymorpha
  • Organogenesis
  • Plant evolution
  • Response regulator

ASJC Scopus subject areas

  • Physiology
  • Plant Science
  • Cell Biology

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  • Cite this

    Aki, S. S., Mikami, T., Naramoto, S., Nishihama, R., Ishizaki, K., Kojima, M., Takebayashi, Y., Sakakibara, H., Kyozuka, J., Kohchi, T., & Umeda, M. (2019). Cytokinin Signaling Is Essential for Organ Formation in Marchantia polymorpha. Plant and Cell Physiology, 60(8), 1842-1854. https://doi.org/10.1093/pcp/pcz100