CLE-like (CLEL) peptides control the pattern of root growth and lateral root development in Arabidopsis

Abstract

CLE peptides, named for the CLV3/ESR-related peptide family, participate in intercellular-signaling pathways. Here we investigated members of the CLE-like (CLEL) gene family that encode peptide precursors recently designated as root growth factors [Matsuzaki Y et al. (2010) Science 329:1065-1067]. CLEL precursors share a similar domain structure with CLE precursors (i.e., they contain a putative Nterminal signal peptide and a C-terminal conserved 13-amino-acid CLEL motif with a variable middle portion). Our evidence shows that, unlike root growth factor, CLEL peptides are (i) unmodified and (ii) function in the regulation of the direction of root growth and lateral root development. Overexpression of several CLEL genes in Arabidopsis resulted in either long roots or long and wavy roots that also showed altered lateral root patterning. Exogenous application of unmodified synthetic 13-amino-acid peptides derived from two CLEL motifs resulted in similar phenotypic changes in roots of wild-type plants. In CLEL peptide-induced long roots, the root apical meristem (RAM) was enlarged and consisted of an increased number of cells, compared with wild-type root apical meristems. The wavy-root phenotype appeared to be independent of other responses of the roots to the environment (e.g., gravitropism, phototropism, and thigmotropism). Results also showed that the inhibition of lateral initiation by CLEL overexpression was not overcome by the application of auxin. These findings establish CLEL as a peptide family with previously unrecognized regulatory functions controlling the pattern of root growth and lateral root development in plants.peptide hormone | root waving | cell division | signal transduction | synthetic peptides S ecreted peptides are important signals in intercellular communication in plants. They elicit signaling pathways that determine the identity and activity of adjacent cells and, in so doing, regulate the structure and function of plant tissues and organs. Secreted peptides are typically derived by proteolytic processing of precursor proteins. They act as signaling ligands, triggering downstream cellular signaling cascade reactions upon binding to a receptor-like kinase (RLK) and/or a receptor-like protein at the plasma membrane (1).The largest group of such peptides identified so far, CLE, named for the CLV3/ESR-related gene family, is thought to function as a 12-or 13-amino-acid (aa) peptide ligand that regulates meristem activity in shoots and roots as well as in vascular tissues (2-6). In several studies, the 12-and 13-aa peptides encoded by specific CLE genes have been detected in plants, and synthetic forms have been shown to functionally mimic the overexpression of corresponding genes (3-6). Accumulated evidence also indicates that secreted peptides are commonly subjected to a variety of posttranslational modifications, such as proline hydroxylation, hydroxyproline arabinosylation, and tyrosine sulfation (3-7).All CLE precursors contain an N-terminal signal peptide and a 14-aa conserved C-terminal...

RGF1 INSENSITIVE 1 to 5, a group of LRR receptor-like kinases, are essential for the perception of root meristem growth factor 1 in Arabidopsis thaliana

“…To test this hypothesis, we treated both Col-0 and the rgi1,2,3,4 quadruple mutant with synthesized sulfated RGF1. Consistent with previous reports, wild-type seedlings showed altered gravitropism response, reduced lateral root formation, and dramatically increased number of meristem cortex cells after the treatment [25][26][27]53]. The quadruple mutant, on the other hand, showed no gravitropism alteration, unchanged lateral root formation, and subtly increased number of meristem cortex cells (Figure 5A-5D).…”

“…For simplicity, we use RGFs hereafter. Like CLE precursor proteins, RGF precursors also contain two major domains, an N-terminal signal peptide sequence and a C-terminal RGF peptide domain [26]. The active peptides contain about 13 amino acids with an Asp-Tyr signature critical for tyrosine sulfation, which is required for the activity of RGFs [25].…”

“…This family of peptides was initially designated as ROOT MERI-STEM GROWTH FACTORS (RGFs) [25]. The same family of peptides was also named CLEL because of the CLEL motifs at their C-termini [26], or GOLVEN (GLV) as transgenic plants overexpressing RGF precursor genes showed wavy root phenotypes on slanted plates, suggesting their roles in regulating plant gravitropic responses [27]. RGF/CLEL/GLV peptide family contains 11 members [28].…”

Drought stress differentially regulates the expression of small open reading frames (sORFs) in Arabidopsis roots and shoots

“…30 For example, peptides belonging to the GLV/RGF/CLEL secreted peptide family have been demonstrated to be involved in plant developmental-related phenomenon, such as the development of root hairs, root meristem maintenance; as well as gravitropism. 20,31 Further experimentation is required to confirm whether or not drought-responsive sORFs encode functional peptides and to elucidate the mechanisms through which these peptides work. In summary, the current study identified sORFs that may represent new players that are involved in the response of soil grown Arabidopsis roots and shoots to drought stress.…”

“…Arabidopsis CLE like (CLEL) genes encode precursors of peptide hormones. [20][21][22] While analyzing the microarray data, we focused on sORFs that were up-regulated in roots at day 7 of the drought stress treatment (q-value <0.1, fold change 2) and divided them into 2 categories; sORFs upregulated only in roots (Fig. 3), and sORFs up-regulated in both roots and shoots (Fig.…”