title: Effect of silicon deficiency on secondary cell wall synthesis in rice leaf.
abstract: Rice (Oryza sativa L.) is a typical Si-accumulating plant and is able to accumulate Si up to >10 % of shoot dry weight. The cell wall has been reported to become thicker under Si-deficient condition. To clarify the relationship between Si accumulation and cell wall components, the physical properties of, and macromolecular components and Si content in, the pectic, hemicellulosic, and cellulosic fractions prepared from rice seedlings grown in hydroponics with or without 1.5 mM silicic acid were analyzed. In the absence of Si (the -Si condition), leaf blades drooped, but physical properties were enhanced. Sugar content in the cellulosic fraction and lignin content in the total cell wall increased under -Si condition. After histochemical staining, there was an increase in cellulose deposition in short cells and the cell layer just beneath the epidermis in the -Si condition, but no significant change in the pattern of lignin deposition. Expression of the genes involved in secondary cell wall synthesis, OsCesA4, OsCesA7, OsPAL, OsCCR1 and OsCAD6 was up-regulated under -Si condition, but expression of OsCesA1, involved in primary cell wall synthesis, did not increase. These results suggest that an increase in secondary cell wall components occurs in rice leaves to compensate for Si deficiency.
authors.affiliation: Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8571, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Atsuko
authors.initials: A
authors.lastname: Nakamura
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Iwai
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ishii
authors.forename: Jian Feng
authors.initials: JF
authors.lastname: Ma
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Yokoyama
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Nishitani
authors.forename: Shinobu
authors.initials: S
authors.lastname: Satoh
authors.forename: Jun
authors.initials: J
authors.lastname: Furukawa
mesh_terms: D002473:Cell Wall / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002482:Cellulose / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018527:Hydroponics / Q000379:methods; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D010368:Pectins / Q000235:genetics / Q000378:metabolism; D059828:Plant Cells / Q000187:drug effects / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D011134:Polysaccharides / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000187:drug effects / Q000502:physiology; D012824:Silicic Acid / Q000494:pharmacology; D012825:Silicon / Q000032:analysis / Q000378:metabolism*
chemical_list: D011134:Polysaccharides; D012824:Silicic Acid; C007916:hemicellulose; D010368:Pectins; D002482:Cellulose; D012825:Silicon