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.
Highlights
CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) peptides are a family of peptide hormones in land plants, mediating cell-to-cell communication in the plant body (Murphy et al, 2012; Hirakawa and Sawa, 2019; Fletcher, 2020)
In Arabidopsis, specific bioactivities of TDIF and CLV3 are attributed to the difference in a few amino acids between them, which are mediated by two distinct groups of receptors, TDIF RECEPTOR/PHLOEM INTERCALTED WITH XYLEM (TDR/PXY) and CLAVATA1/BARELY ANY MERISTEMs (CLV1/BAMs), respectively (Fletcher et al, 1999; DeYoung et al, 2006; Fisher and Turner, 2007; Hirakawa et al, 2008, 2017; Ogawa et al, 2008; Rodriguez-Villalon et al, 2014; Shimizu et al, 2015; Shinohara and Matsubayashi, 2015; Crook et al, 2020)
Since the genetic analysis suggests that MpCLAVATA3 INSENSITIVE RECEPTOR KINASE (MpCIK) may function as a coreceptor for MpCLV1 for the perception of MpCLE2 peptide, we examined the biochemical interaction between MpCIK and MpCLV1 proteins expressed in a Nicotiana benthamiana transient expression system, which has been utilized to analyze the interaction of CLV and CLAVATA3 INSENSITIVE RECEPTOR KINASEs (CIKs) receptors of Arabidopsis (Kinoshita et al, 2010; Betsuyaku et al, 2011; Hu et al, 2018)
Summary
CLAVATA3/EMBRYO SURROUNDING REGION-related (CLE) peptides are a family of peptide hormones in land plants, mediating cell-to-cell communication in the plant body (Murphy et al, 2012; Hirakawa and Sawa, 2019; Fletcher, 2020). In bryophytes, which are distantly related to flowering plants in the land plant lineage (Morris et al, 2018; Puttick et al, 2018), relatively low number of CLE genes are encoded in the genome, providing simplified models to study the function of CLE genes (Bowman et al, 2017; Whitewoods et al, 2018). MpCLE1-MpTDR signaling acts as a negative regulator of cell proliferation at the apical notch, while MpCLE2-MpCLV1 signaling functions as a positive regulator of stem cell activity in the apical notch (Hirakawa et al, 2019, 2020)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
