title: Xylan synthesized by Irregular Xylem 14 (IRX14) maintains the structure of seed coat mucilage in Arabidopsis.
abstract: During differentiation, the Arabidopsis seed coat epidermal cells synthesize and secrete large quantities of pectinaceous mucilage into the apoplast, which is then released to encapsulate the seed upon imbibition. In this study, we showed that mutation in Irregular Xylem 14 (IRX14) led to a mucilage cohesiveness defect due to a reduced xylan content. Expression of IRX14 was detected specifically in the seed coat epidermal cells, reaching peak expression at 13 days post-anthesis (DPA) when the accumulation of mucilage polysaccharides has ceased. Sectioning of the irx14-1 seed coat revealed no visible structural change in mucilage secretory cell morphology. Although the total amount of mucilage was comparable with the wild type (WT), the partition between water-soluble and adherent layers was significantly altered in irx14-1, with redistribution from the adherent layer to the water-soluble layer. The monosaccharide composition analysis revealed that xylose content was significantly reduced in irx14-1 water-soluble and adherent mucilage compared with the WT. The macromolecular characteristics of the water-soluble mucilage were modified in irx14-1 with a loss of the larger polymeric components. In accordance, glycome profiling and dot immunoblotting of seed mucilage using antibodies specific for rhamnogalacturonan I (RG I) and xylan confirmed the ultra-structural alterations in the irx14-1 mucilage. Meanwhile, the crystalline cellulose content was reduced in the irx14-1 mucilage. These results demonstrated that IRX14 was required for the biosynthesis of seed mucilage xylan, which plays an essential role in maintaining mucilage architecture potentially through altering the crystallization and organization of cellulose.
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China.
authors.forename: Ruibo
authors.initials: R
authors.lastname: Hu
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China.
authors.forename: Junling
authors.initials: J
authors.lastname: Li
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Wang
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China.
authors.forename: Xun
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China.
authors.forename: Xuanwen
authors.initials: X
authors.lastname: Yang
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Tang
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China.
authors.forename: Guo
authors.initials: G
authors.lastname: He
authors.affiliation: Qingdao Engineering Research Center of Biomass Resources and Environment, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, P.R. China zhougk@qibebt.ac.cn kongyingzhen@163.com.
authors.forename: Gongke
authors.initials: G
authors.lastname: Zhou
authors.affiliation: Key laboratory of Tobacco Genetic Improvement and Biotechnology, Tobacco Research Institute of Chinese Academy of Agricultural Sciences, Qingdao 266101, P.R. China zhougk@qibebt.ac.cn kongyingzhen@163.com.
authors.forename: Yingzhen
authors.initials: Y
authors.lastname: Kong
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism; D003460:Crystallization; D018506:Gene Expression Regulation, Plant; D015151:Immunoblotting; D046911:Macromolecular Substances / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010430:Pentosyltransferases / Q000235:genetics / Q000378:metabolism*; D062087:Plant Mucilage / Q000378:metabolism*; D012639:Seeds / Q000033:anatomy & histology* / Q000378:metabolism*; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water; D014990:Xylans / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D046911:Macromolecular Substances; D062087:Plant Mucilage; D014990:Xylans; D014867:Water; D002482:Cellulose; D014994:Xylose; C571990:IRX14 protein, Arabidopsis; D010430:Pentosyltransferases
keywords: Arabidopsis; IRX14; crystalline cellulose; mucilage; xylan.
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