An Evolutionarily Conserved Coreceptor Gene Is Essential for CLAVATA Signaling in Marchantia polymorpha

Abstract

Growth and development of land plants are controlled by CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) family of peptide hormones. In contrast to the genetic diversity of CLE family in flowering plants, the liverwort Marchantia polymorpha possesses a minimal set of CLE, MpCLE1(TDIF homolog), and MpCLE2 (CLV3 homolog). MpCLE1 and MpCLE2 peptides exert distinct function at the apical meristem of M. polymorpha gametophyte via specific receptors, MpTDIF RECEPTOR (MpTDR) and MpCLAVATA1 (MpCLV1), respectively, both belonging to the subclass XI of leucine-rich repeat receptor-like kinases (LRR-RLKs). Biochemical and genetic studies in Arabidopsis have shown that TDR/PXY family and CLV1/BAM family recognize the CLE peptide ligand in a heterodimeric complex with a member of subclass-II coreceptors. Here we show that three LRR-RLK genes of M. polymorpha are classified into subclass II, representing three distinct subgroups evolutionarily conserved in land plants. To address the involvement of subclass-II coreceptors in M. polymorpha CLE signaling, we performed molecular genetic analysis on one of them, MpCLAVATA3 INSENSITIVE RECEPTOR KINASE (MpCIK). Two knockout alleles for MpCIK formed narrow apical meristems marked by promMpYUC2:GUS marker, which were not expanded by MpCLE2 peptide treatment, phenocopying Mpclv1. Loss of sensitivity to MpCLE2 peptide was also observed in gemma cup formation in both Mpclv1 and Mpcik. Biochemical analysis using a Nicotiana benthamiana transient expression system revealed weak association between MpCIK and MpCLV1, as well as MpCIK and MpTDR. While MpCIK may also participate in MpCLE1 signaling, our data show that the conserved CLV3-CLV1-CIK module functions in M. polymorpha, controlling meristem activity for development and organ formation for asexual reproduction.

The wound-activated ERF15 transcription factor drives Marchantia polymorpha regeneration by activating an oxylipin biosynthesis feedback loop

“…4I ). To investigate whether the ectopic concave structures in Mp ERF15 OE function as meristems, we introduced the Mp ERF15 OE expression vector in the apical notch marker line pro Mp YUC2 :GUS ( 36 , 37 ). Overexpression of Mp ERF15 resulted in approximately eight blue GUS dots in the 10-day-old thallus, being significantly more than the four blue dots in the Tak-1 background ( Fig.…”

How was apical growth regulated in the ancestral land plant? Insights from the development of non-seed plants

“…Orthologs of CLV3 , CLV1/BAM1 , RPK2 , and CIK are present in bryophyte genomes, whereas CLV2 and CRN emerged in vascular plants. None of these genes are present in charophyte algae, suggesting that a core CLV signaling network evolved in the ancestor of land plants and was later elaborated during land plant evolution ( Whitewoods et al, 2018 ; Furumizu et al, 2021 ; Takahashi et al, 2021 ). In Physcomitrium , loss-of-function Ppclv1a/1b and Pprpk2 mutants produce an over-proliferation of apical cells at the base of gametophores.…”

“…Moreover, application of synthetic CLV3-like peptides inhibits cell proliferation and causes gametophore dwarfing ( Whitewoods et al, 2018 ). In Marchantia , a CLV3–CLV1–CIK module also regulates gametophytic stem cell proliferation, although in this case positively ( Hirakawa et al, 2020 ; Takahashi et al, 2021 ). Intriguingly, a CLV3 family member that promotes stem cell proliferation in Arabidopsis has been found to repress apical growth in Marchantia ( Hirakawa et al, 2019 ), suggesting a divergence of signaling mechanisms during evolution.…”

KARRIKIN INSENSITIVE2(KAI2)-dependent signaling pathway controls vegetative reproduction inMarchantia polymorpha

“…MpCLE2, the closest homolog of CLAVATA3 (CLV3) of Arabidopsis, affects gemma cup formation through a conserved CLV3-CLV1-CIK module [11,12].…”