title: Restriction of cell proliferation in internal tissues via the synthesis of very-long-chain fatty acids in the epidermis.
abstract: Very-long-chain fatty acids (VLCFAs) are major components of cuticular wax and are also contained in seed storage triacylglycerols and sphingolipids. Arabidopsis mutants with severe defects in VLCFA synthesis produce fused leaves because of impaired cuticle formation. We recently reported that a small decrease in VLCFA content did not cause growth defects, but instead led to enhanced cell proliferation in internal tissues. We observed that this overproliferation was induced by elevated expression of cytokinin biosynthesis genes, which in turn increased the cytokinin level. Interestingly, VLCFAs are specifically synthesized in the epidermis for cuticular wax secretion, whereas cytokinin biosynthesis mainly occurs in the vasculature. Our results indicate the requirement of VLCFA synthesis in the epidermis for sending non-autonomous signals, thereby suppressing cytokinin biosynthesis in the vasculature. We propose that the interaction between the surface (epidermis) and axis (vasculature) of the plant body fine-tunes cell division activity and restricts organ size in determinate growth.
authors.affiliation: Graduate School of Biological Sciences; Nara Institute of Science and Technology; Ikoma, Nara, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nobusawa
authors.forename: Yoko
authors.initials: Y
authors.lastname: Okushima
authors.forename: Noriko
authors.initials: N
authors.lastname: Nagata
authors.forename: Mikiko
authors.initials: M
authors.lastname: Kojima
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sakakibara
authors.forename: Masaaki
authors.initials: M
authors.lastname: Umeda
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism*; D002455:Cell Division; D049109:Cell Proliferation; D003583:Cytokinins / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis*; D008954:Models, Biological; D038081:Organogenesis; D019441:Plant Epidermis / Q000166:cytology* / Q000378:metabolism*; D058526:Plant Vascular Bundle / Q000166:cytology / Q000378:metabolism
chemical_list: D003583:Cytokinins; D005227:Fatty Acids
keywords: cell proliferation; cytokinin; epidermis; non-autonomous signal; organ growth; organ size; vasculature; very-long-chain fatty acid