Tri-arabinosylation facilitates the bioactivity of CLE3 peptide in Arabidopsis

Post-translational modification is critical for the bioactivity of small secreted-signaling peptides. The shoot apical meristem (SAM) activity that defines SAM size is controlled by the CLAVATA3 (CLV3) peptide ligand, which belongs to the CLV3/EMBRYO SURROUNDING REGIONRELATED (CLE) family, and its cognate receptor CLV1. The mature CLV3 peptide is post-translationally modified with tri-arabinose, increasing the binding affinity with CLV1. However, the mature form of most CLE peptides is unknown. Here we apply the synthetic CLE3 peptide with tri-arabinose to clv3 mutant to determine whether the CLE3 peptide can reduce the SAM size. We show that tri-arabinosylated CLE3 peptide exhibits stronger bioactivity in the SAM in a CLV1/BAM1-dependent manner. Our data emphasizes the importance of post-translational modification on peptide signaling, helping to characterize bona fide mature peptides.