Dual CLAVATA3 peptides in Arabidopsis shoot stem cell signaling

Abstract

Plant shoot stem cell pool is constantly maintained by a negative feedback loop through peptide-receptor mediated signaling pathway. CLAVATA3 (CLV3) encode a 96 amino-acid protein which is processed to 12-amino-acid or arabinosylated 13-amino-acid peptides, acting as a ligand signal to regulate stem cell homeostasis in the shoot apical meristem (SAM). Although arabinosylated 13-amino-acid CLV3 peptide (CLV3p) shows more significant binding affinity to its receptors and biological activities in the SAM, the physiological function of two mature forms of CLV3p remained an unresolved puzzle in the past decade due to the technical difficulties of arabinosylation modification in the peptide synthesis. Here, we analyzed the role of two mature CLV3 peptides with newly synthesized arabinosylated peptide. Beside shoot meristem phenotypes, arabinosylated CLV3p showed the conventional trait of CLV2-dependent root growth inhibition. Moreover, both 12-amino-acid and arabinosylated 13-amino-acid CLV3 peptides have analogous activities in shoot stem cell signaling. Notably, we demonstrated that non-arabinosylated 12-amino acid CLV3p can affect shoot stem cell signaling at the physiological level unlike previously suggested (Ohyama et al., 2009; Shinohara and Matsubayashi, 2013; Shinohara and Matsubayashi, 2015). Therefore, these results support the physiological role of the 12-amino-acid CLV3p in shoot stem cell signaling in the deficient condition of arabinosylated 13-amino-acid CLV3p in Arabidopsis thaliana.

Look Closely, the Beautiful May Be Small: Precursor-Derived Peptides in Plants

“…In contrast to tomato, the Arabidopsis hpat1 hpat2 hpat3 triple mutant does not have an enlarged meristem (101,128), suggesting that a requirement for PTM of the CLV3 peptide may not be conserved across plant species or that arabinosylation of Arabidopsis CLV3 is not essential for its biological activity (134). Recent research showed a higher binding affinity of the arabinosylated Arabidopsis CLV3 to the CLV1 receptor; however, both the arabinosylated and the non-arabinosylated CLV3 peptides were able to rescue a clv3-2 mutant phenotype at the same concentration, providing evidence that both CLV3 peptides are functional in Arabidopsis (82).…”

Mitogen-activated protein kinases MPK3 and MPK6 are required for stem cell maintenance in the Arabidopsis shoot apical meristem

“…The shoot apex tissues were harvested, fixed and embedded using the same procedures as for the SAM arrest assay (Kim et al 2017). Antigen unmasking using sodium citrate was conducted according to the manufacturer's instructions (Zymed).…”

“…For measurement of the SAM size, seedlings were grown on MS plate for 1 week and transferred into new MS plates with 10 μM estradiol under a 12 h light/12 h dark photoperiod for 10 days. Shoot apices of seedlings were sampled and fixed in 4% paraformaldehyde/4% DMSO solution at 4°C for 16 h. Paraffin embedding and sections were performed as described previously (Kim et al 2017). Sectioned samples were stained with 0.1% Giemsa (Sigma) for 2 min and rinsed briefly with water.…”

Predicting and Clustering Plant CLE Genes with a New Method Developed Specifically for Short Amino Acid Sequences

“…Interestingly, the in uence of these post-translational modi cations varies in different species. For instance, posttranslational modi cations are critical for the activity of the CLV3 peptides in tomato but not in Arabidopsis [14,15]. Typically, the mature forms of CLE peptides are recognized by plasma membranelocalized leucine-rich repeat receptor-like kinases (LRR-RLK) or receptor-like proteins (LRR-RLP) [16][17][18].…”