Root-specific CLE19 overexpression and the sol1/2 suppressors implicate a CLV-like pathway in the control of Arabidopsis root meristem maintenance.
In the Arabidopsis shoot apical meristem, an organizing center signals in a non-cell-autonomous manner to specify the overlying stem cells. Stem cells express the small, secreted protein CLAVATA3 (CLV3; ) that activates the CLV1-CLV2 receptor complex, which negatively controls the size of the organizing center. Consistently, CLV3 overexpression restricts shoot meristem size. The root meristem also contains a stem cell organizer, and here we show that localized overexpression in roots of CLE19, encoding a CLV3 homolog, restricts the size of the root meristem. This suggests that CLE19 acts by overactivating an endogenous CLV-like pathway involved in root meristem maintenance. Surprisingly, CLE19 restricts meristem size without directly interfering with organizer and stem cell specification. We isolated mutations in two loci, SOL1 and SOL2, which suppress the CLE19 overexpression phenotype. sol2 plants display floral phenotypes reminiscent of clv weak alleles; these phenotypes suggest that components of a CLV pathway are shared in roots and shoots. SOL1 encodes a putative Zn(2+)-carboxypeptidase, which may be involved in ligand processing.
Casamitjana-Martínez
Eva
E
Developmental Genetics, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands.
Hofhuis
Hugo F
HF
Xu
Jian
J
Liu
Chun-Ming
CM
Heidstra
Renze
R
Scheres
Ben
B
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002268:Carboxypeptidases / Q000235:genetics / Q000378:metabolism; D035264:Flowers / Q000254:growth & development / Q000378:metabolism; D015870:Gene Expression; D017343:Genes, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D018519:Meristem / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D018517:Plant Roots / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013234:Stem Cells / Q000378:metabolism
C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; C401621:CLV2 protein, Arabidopsis; D008565:Membrane Proteins; D020794:Receptor Protein-Tyrosine Kinases; C118166:CLV1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases; D002268:Carboxypeptidases