Abstract
CLE (CLAVATA3/ESR) peptides precisely regulate cell proliferation and differentiation by acting as signaling molecules in cell-cell communication. In Arabidopsis, there are 32 CLE genes including CLV3 and CLE41/44, which encode TDIF (Tracheary element differentiation inhibitory factor). However, the roles of most CLE peptides have not been revealed yet. To know novel function of CLE peptides, we comprehensively examined the effects of chemically synthesized CLE peptides on root xylem development. This physiological analysis revealed that CLE peptides inhibited protoxylem vessel formation, independently of root growth arrest. This function was also proved by phenotype analyses of CLE receptor mutant and CLE-overexpressing transgenic plants. Next we performed transcriptome analysis when treated with or without CLE peptides. Interestingly, CLE peptides application reduced the expression levels of type-A ARRs, which negatively regulate cytokinin signal transduction. These results together with data from genetic analysis using cytokinin-related mutants clarified cross-talk between CLE peptides and cytokinin signaling pathways in protoxylem vessel formation.
