Abstract
Communication between plant cells and their biotic environment is largely dependent on the function of plasma membrane localized receptor-like kinases (RLKs). Major players in this communication within root meristems are secreted peptides, including CLAVATA3/EMBRYO SURROUNDING REGION40 (CLE40). In the distal root meristem, CLE40 acts through the receptor like kinase (RLK) ARABIDOPSIS CRINKLY4 (ACR4) and the leucine-rich repeat (LRR) RLK CLAVATA1 (CLV1) to promote cell differentiation. In the proximal meristem, CLE40 signalling requires the LRR receptor-like protein (RLP) CLAVATA2 (CLV2) and the membrane localized pseudokinase CORYNE (CRN), and serves to inhibit cell differentiation. The molecular components that act immediately downstream of the CLE40-activated receptors are not yet known. Here we show that active CLE40 signalling triggers the release of intracellular Ca2+ leading to increased cytosolic Ca2+ concentration ([Ca2+]cyt) in a subset of proximal root meristem cells. This rise in [Ca2+]cyt depends on the CYCLIC NUCLEOTIDE GATED CHANNEL 9 (CNGC9), CLV1, the CLV1-related BARELY ANY MERISTEM1 (BAM1), CLV2 and CRN. The precise function of changes in [Ca2+]cyt are not yet known, but might form a central part of a fine-tuned response to CLE40 peptide that serves to integrate root meristem growth with stem cell fate decisions and initiation of lateral root primordia.
Competing Interest Statement
The authors have declared no competing interest.