The RopGEF KARAPPO Is Essential for the Initiation of Vegetative Reproduction in Marchantia polymorpha

Takuma Hiwatashi, Honzhen Goh, Yukiko Yasui, Li Quan Koh, Hideyuki Takami, Masataka Kajikawa, Hiroyuki Kirita, Takehiko Kanazawa, Naoki Minamino, Taisuke Togawa, Mayuko Sato, Mayumi Wakazaki, Katsushi Yamaguchi, Shuji Shigenobu, Hidehiro Fukaki, Tetsuro Mimura, Kiminori Toyooka, Shinichiro Sawa, Katsuyuki T. Yamato, Takashi UedaDaisuke Urano, Takayuki Kohchi, Kimitsune Ishizaki

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

Many plants can reproduce vegetatively, producing clonal progeny from vegetative cells; however, little is known about the molecular mechanisms underlying this process. Liverwort (Marchantia polymorpha), a basal land plant, propagates asexually via gemmae, which are clonal plantlets formed in gemma cups on the dorsal side of the vegetative thallus [1]. The initial stage of gemma development involves elongation and asymmetric divisions of a specific type of epidermal cell, called a gemma initial, which forms on the floor of the gemma cup [2, 3]. To investigate the regulatory mechanism underlying gemma development, we focused on two allelic mutants in which no gemma initial formed; these mutants were named karappo, meaning “empty.” We used whole-genome sequencing of both mutants and molecular genetic analysis to identify the causal gene, KARAPPO (KAR), which encodes a ROP guanine nucleotide exchange factor (RopGEF) carrying a plant-specific ROP nucleotide exchanger (PRONE) catalytic domain. In vitro GEF assays showed that the full-length KAR protein and the PRONE domain have significant GEF activity toward MpROP, the only ROP GTPase in M. polymorpha. Moreover, genetic complementation experiments showed a significant role for the N- and C-terminal variable regions in gemma development. Our investigation demonstrates an essential role for KAR/RopGEF in the initiation of plantlet development from a differentiated cell, which may involve cell-polarity formation and subsequent asymmetric cell division via activation of ROP signaling, implying a similar developmental mechanism in vegetative reproduction of various land plants. Many plants have the ability to reproduce asexually by producing clonal plantlets directly from vegetative organs. Hiwatashi et al. identify a PRONE-type activator of ROP GTPase as an essential regulator for initiation of plantlet development in the basal land plant Marchantia polymorpha.

Original languageEnglish
Pages (from-to)3525-3531.e7
JournalCurrent Biology
Volume29
Issue number20
DOIs
Publication statusPublished - 2019 Oct 21

All Science Journal Classification (ASJC) codes

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

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