title: Apical meristem exhaustion during determinate primary root growth in the moots koom 1 mutant of Arabidopsis thaliana.
abstract: An indeterminate developmental program allows plant organs to grow continuously by maintaining functional meristems over time. The molecular mechanisms involved in the maintenance of the root apical meristem are not completely understood. We have identified a new Arabidopsis thaliana mutant named moots koom 1 (mko1) that showed complete root apical meristem exhaustion of the primary root by 9 days post-germination. MKO1 is essential for maintenance of root cell proliferation. In the mutant, cell division is uncoupled from cell growth in the region corresponding to the root apical meristem. We established the sequence of cellular events that lead to meristem exhaustion in this mutant. Interestingly, the SCR and WOX5 promoters were active in the mko1 quiescent center at all developmental stages. However, during meristem exhaustion, the mutant root tip showed defects in starch accumulation in the columella and changes in auxin response pattern. Therefore, contrary to many described mutants, the determinate growth in mko1 seedlings does not appear to be a consequence of incorrect establishment or affected maintenance of the quiescent center but rather of cell proliferation defects both in stem cell niche and in the rest of the apical meristem. Our results support a model whereby the MKO1 gene plays an important role in the maintenance of the root apical meristem proliferative capacity and indeterminate root growth, which apparently acts independently of the SCR/SHR and WOX5 regulatory pathways.
authors: Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Apartado Postal 510-3, 62250, Cuernavaca, Morelos, Mexico.
authors: Alejandra
authors: A
authors: Hernández-Barrera
authors: Yamel
authors: Y
authors: Ugartechea-Chirino
authors: Svetlana
authors: S
authors: Shishkova
authors: Selene
authors: S
authors: Napsucialy-Mendivil
authors: Aleš
authors: A
authors: Soukup
authors: Blanca Jazmín
authors: BJ
authors: Reyes-Hernández
authors: Verónica
authors: V
authors: Lira-Ruan
authors: Gaofeng
authors: G
authors: Dong
authors: Joseph G
authors: JG
authors: Dubrovsky
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D018525:Germination; D018398:Homeodomain Proteins / Q000235:genetics; D007210:Indoleacetic Acids / Q000494:pharmacology*; D018519:Meristem / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D009154:Mutation; D010641:Phenotype; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D011401:Promoter Regions, Genetic / Q000235:genetics; D036226:Seedlings / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D015398:Signal Transduction / Q000235:genetics; D055153:Stem Cell Niche; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators; C410510:SHORT ROOT protein, Arabidopsis; D014157:Transcription Factors; C116421:WUSCHEL protein, Arabidopsis