CLE polypeptide signaling gene expression in Arabidopsis embryos.

The CLAVATA3 (CLV3)/ESR-related (CLE) family of small polypeptides mediate intercellular signaling events in plants. The biological roles of several CLE family members have been characterized, but the function of the majority still remains elusive. We recently performed a systematic expression analysis of 23 Arabidopsis CLE genes to gain insight into the developmental processes they may potentially regulate during vegetative and reproductive growth. Our study revealed that each Arabidopsis tissue expresses one or more CLE genes, suggesting that they might play roles in many developmental and/or physiological processes. Here we determined the expression patterns of nine Arabidopsis CLE gene promoters in mature embryos and compared them to the known expression patterns in seedlings. We found that more than half of these CLE genes have similar expression profiles at the embryo and seedling stages, whereas the rest differ dramatically. The implications of these findings in understanding the biological processes controlled by these CLE genes are discussed.

Comprehensive analysis of CLE polypeptide signaling gene expression and overexpression activity in Arabidopsis.

Intercellular signaling is essential for the coordination of growth and development in higher plants. Although hundreds of putative receptors have been identified in Arabidopsis (Arabidopsis thaliana), only a few families of extracellular signaling molecules have been discovered, and their biological roles are largely unknown. To expand our insight into the developmental processes potentially regulated by ligand-mediated signal transduction pathways, we undertook a systematic expression analysis of the members of the Arabidopsis CLAVATA3/ESR-RELATED (CLE) small signaling polypeptide family. Using reporter constructs, we show that the CLE genes have distinct and specific patterns of promoter activity. We find that each Arabidopsis tissue expresses at least one CLE gene, indicating that CLE-mediated signaling pathways are likely to play roles in many biological processes during the plant life cycle. Some CLE genes that are closely related in sequence have dissimilar expression profiles, yet in many tissues multiple CLE genes have overlapping patterns of promoter-driven reporter activity. This observation, plus the general absence of detectable morphological phenotypes in cle null mutants, suggest that a high degree of functional redundancy exists among CLE gene family members. Our work establishes a community resource of CLE-related biological materials and provides a platform for understanding and ultimately manipulating many different plant signaling systems.