InterPro domain: IPR037495

This entry includes CLAVATA3/ESR (CLE)-related protein 41/42/44 (CLE41/42/44) from Arabidopsis and TDIF from Zinnia violacea. TDIF functions as a phloem-derived, non-cell-autonomous signal that controls stem cell fate in the procambium [ 1 ].

Tracheary element differentiation inhibition factor (TDIF; CLE41/CLE44 peptide) and CLE42 peptide of Arabidopsis have almost identical amino acid sequences and act as inhibitors of tracheary element differentiation. TDIF/CLE41/CLE44 promote the proliferation of vascular cells and prevent them from differentiating into xylem by regulating WOX4 expression through the TDR/PXY receptor [ 2 , 2 , 3 ]. CLE42 binds PXL2 (PXY-like 2) [ 4 ]. TDIF-related peptides also have activity to enhance axillary bud formation [ 5 ].

The CLE proteins share a C-terminal CLE domain with CLV3, a small secreted polypeptide that is active as a ligand and has a function in shoot apical meristem maintenance [ 6 ]. In general, the CLE-related proteins are C-terminally processed to generate an active CLE peptide [ 7 ]. These small secreted peptide hormones then function in a variety of developmental and physiological processes [ 8 , 9 ]. CLV3 and other A-type CLE peptides are involved in the suppression of stem cell development in root and shoot development, in contrast to the B-type CLE peptides, CLE41 and CLE44, in the case of Arabidopsis, which are not [ 10 ].

1. Non-cell-autonomous control of vascular stem cell fate by a CLE peptide/receptor system. Proc. Natl. Acad. Sci. U.S.A. 105, 15208-13
2. TDIF peptide signaling regulates vascular stem cell proliferation via the WOX4 homeobox gene in Arabidopsis. Plant Cell 22, 2618-29
3. CLE peptides in vascular development. J Integr Plant Biol 55, 389-94
4. CLE42 binding induces PXL2 interaction with SERK2. Protein Cell 8, 612-617
5. A novel function of TDIF-related peptides: promotion of axillary bud formation. Plant Cell Physiol. 52, 1354-64
6. The Arabidopsis CLV3-like (CLE) genes are expressed in diverse tissues and encode secreted proteins. Plant Mol. Biol. 51, 415-25
7. Evidence for functional conservation, sufficiency, and proteolytic processing of the CLAVATA3 CLE domain. Plant Physiol. 140, 726-33
8. CLE signaling systems during plant development and nematode infection. Plant Cell Physiol. 53, 1989-99
9. Gain-of-function phenotypes of many CLAVATA3/ESR genes, including four new family members, correlate with tandem variations in the conserved CLAVATA3/ESR domain. Plant Physiol. 140, 1331-44
10. Plant CLE peptides from two distinct functional classes synergistically induce division of vascular cells. Proc. Natl. Acad. Sci. U.S.A. 105, 18625-30