title: CELLULOSE SYNTHASE-LIKE A2, a glucomannan synthase, is involved in maintaining adherent mucilage structure in Arabidopsis seed.
abstract: Mannans are hemicellulosic polysaccharides that are considered to have both structural and storage functions in the plant cell wall. However, it is not yet known how mannans function in Arabidopsis (Arabidopsis thaliana) seed mucilage. In this study, CELLULOSE SYNTHASE-LIKE A2 (CSLA2; At5g22740) expression was observed in several seed tissues, including the epidermal cells of developing seed coats. Disruption of CSLA2 resulted in thinner adherent mucilage halos, although the total amount of the adherent mucilage did not change compared with the wild type. This suggested that the adherent mucilage in the mutant was more compact compared with that of the wild type. In accordance with the role of CSLA2 in glucomannan synthesis, csla2-1 mucilage contained 30% less mannosyl and glucosyl content than did the wild type. No appreciable changes in the composition, structure, or macromolecular properties were observed for nonmannan polysaccharides in mutant mucilage. Biochemical analysis revealed that cellulose crystallinity was substantially reduced in csla2-1 mucilage; this was supported by the removal of most mucilage cellulose through treatment of csla2-1 seeds with endo-β-glucanase. Mutation in CSLA2 also resulted in altered spatial distribution of cellulose and an absence of birefringent cellulose microfibrils within the adherent mucilage. As with the observed changes in crystalline cellulose, the spatial distribution of pectin was also modified in csla2-1 mucilage. Taken together, our results demonstrate that glucomannans synthesized by CSLA2 are involved in modulating the structure of adherent mucilage, potentially through altering cellulose organization and crystallization.
authors.affiliation: Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Energy Genetics, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, P.R. China.
authors.forename: Li
authors.initials: L
authors.lastname: Yu
authors.forename: Dachuan
authors.initials: D
authors.lastname: Shi
authors.forename: Junling
authors.initials: J
authors.lastname: Li
authors.forename: Yingzhen
authors.initials: Y
authors.lastname: Kong
authors.forename: Yanchong
authors.initials: Y
authors.lastname: Yu
authors.forename: Guohua
authors.initials: G
authors.lastname: Chai
authors.forename: Ruibo
authors.initials: R
authors.lastname: Hu
authors.forename: Juan
authors.initials: J
authors.lastname: Wang
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hahn
authors.forename: Gongke
authors.initials: G
authors.lastname: Zhou
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism; D003460:Crystallization; D018506:Gene Expression Regulation, Plant; D008040:Genetic Linkage; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008351:Mannans / Q000096:biosynthesis*; D009154:Mutation / Q000235:genetics; D010368:Pectins / Q000378:metabolism; D062087:Plant Mucilage / Q000378:metabolism* / Q000648:ultrastructure; D021381:Protein Transport; D012639:Seeds / Q000201:enzymology* / Q000378:metabolism* / Q000648:ultrastructure; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D029681:Arabidopsis Proteins; D008351:Mannans; D062087:Plant Mucilage; D049452:Green Fluorescent Proteins; C022901:(1-6)-alpha-glucomannan; D010368:Pectins; D002482:Cellulose; C000593207:CELLULOSE SYNTHASE-LIKE A2 protein, Arabidopsis; D005964:Glucosyltransferases; C478648:cellulose synthase