title: The conflict between cell proliferation and expansion primarily affects stem organogenesis in Arabidopsis.
abstract: Plant shoot organs such as stems, leaves and flowers are derived from specialized groups of stem cells organized at the shoot apical meristem (SAM). Organogenesis involves two major processes, namely cell proliferation and differentiation, whereby the former contributes to increasing the cell number and the latter involves substantial increases in cell volume through cell expansion. Co-ordination between the above processes in time and space is essential for proper organogenesis. To identify regulatory factors involved in proper organogenesis, heavy-ion beam-irradiated de-etiolated (det) 3-1 seeds have been used to identify striking phenotypes in the A#26-2; det3-1 mutant. In addition to the stunted plant stature mimicking det3-1, the A#26-2; det3-1 mutant exhibited stem thickening, increased floral organ number and a fruit shape reminiscent of clavata (clv) mutants. DNA sequencing analysis demonstrated that A#26-2; det3-1 harbors a mutation in the CLV3 gene. Importantly, A#26-2; det3-1 displayed cracks that randomly occurred on the main stem with a frequency of approximately 50%. Furthermore, the double mutants clv3-8 det3-1, clv1-4 det3-1 and clv2-1 det3-1 consistently showed stem cracks with frequencies of approximately 97, 38 and 35%, respectively. Cross-sections of stems further revealed an increase in vascular bundle number, cell number and size in the pith of clv3-8 det3-1 compared with det3-1. These findings suggest that the stem inner volume increase due to clv mutations exerts an outward mechanical stress; that in a det3-1 background (defective in cell expansion) resulted in cracking of the outermost layer of epidermal cells.
authors.affiliation: Department of Biology, Tokyo Gakugei University, Koganei-shi, 184-8501 Japan These authors contributed equally to this work.
authors.forename: Saori
authors.initials: S
authors.lastname: Maeda
authors.affiliation: Department of Biology, Tokyo Gakugei University, Koganei-shi, 184-8501 Japan These authors contributed equally to this work.
authors.forename: Shizuka
authors.initials: S
authors.lastname: Gunji
authors.affiliation: Department of Biology, Tokyo Gakugei University, Koganei-shi, 184-8501 Japan These authors contributed equally to this work.
authors.forename: Kenya
authors.initials: K
authors.lastname: Hanai
authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan.
authors.forename: Tomonari
authors.initials: T
authors.lastname: Hirano
authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Kazama
authors.affiliation: Department of Biology, Tokyo Gakugei University, Koganei-shi, 184-8501 Japan.
authors.forename: Iwai
authors.initials: I
authors.lastname: Ohbayashi
authors.affiliation: RIKEN Nishina Center, 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Abe
authors.affiliation: Graduate School of Science and Technology, Kumamoto University, Chuo-ku, 860-8555 Japan.
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Sawa
authors.affiliation: Department of Biological Sciences, Graduate School of Science, University of Tokyo, Bunkyo-ku, 113-0033 Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Tsukaya
authors.affiliation: Department of Biology, Tokyo Gakugei University, Koganei-shi, 184-8501 Japan ferjani@u-gakugei.ac.jp.
authors.forename: Ali
authors.initials: A
authors.lastname: Ferjani
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D049109:Cell Proliferation; D048429:Cell Size; D035264:Flowers / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008854:Microscopy, Electron; D009154:Mutation; D063246:Organogenesis, Plant / Q000502:physiology*; D010641:Phenotype; D018547:Plant Stems / Q000166:cytology* / Q000235:genetics / Q000254:growth & development*; D017346:Protein Serine-Threonine Kinases; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: 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
keywords: Arabidopsis; Mechanical stress; Organogenesis; Stem; Stem cracking; clavata; det3-1