title: HAM proteins promote organ indeterminacy: but how?
abstract: HAIRY MERISTEM (HAM) proteins, members of the GRAS family of transcriptional regulators, are essential for maintenance of indeterminate growth in flowering plant shoots, loss-of-function ham mutants exhibiting a strikingly novel phenotype of shoot meristem arrest and differentiation. Specific cellular/molecular functions of HAM proteins underlying meristem maintenance are unknown. In this review, I highlight findings from recent analyses of Arabidopsis ham (Atham) loss-of-function phenotypes, including that HAM function limits the generation of clonally-derived meristem layers and that HAM function regulates CLAVATA3 expression. I consider how this new information both refines our understanding of the role of HAM proteins in regulating meristem structure and function, and may also suggest possible downstream HAM protein transcriptional targets. Finally, I note the significant phenotypic overlap between Atham phenotypes, and aintegumenta/anintegumenta-like6 double mutant phenotypes, suggesting meristem regulatory functions common to, and possible genetic interactions between, HAM and AINTEGUMENTA.
authors.affiliation: Biology Department, The College of William and Mary, Williamsburg, VA, USA. emengs@wm.edu
authors.forename: Eric M
authors.initials: EM
authors.lastname: Engstrom
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018519:Meristem / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D018520:Plant Shoots / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C099055:AINTEGUMENTA protein, Arabidopsis; C118167:AT2G27250 protein, Arabidopsis; D029681:Arabidopsis Proteins; D014157:Transcription Factors