Glycosyltransferase Genes Involved in Xyloglucan Biosynthesis

Minmin Xie, Jiangtao Chao, Yingzhen Kong

Chinese Bulletin of Botany 2015, 50 (5): 644-. DOI: 10.11983/CBB14172

Abstract （1070）

HTML （12）

PDF（pc）（326KB）（1596）

The hemicellulosic polysaccharide xyloglucan (XyG), found in the primary cell walls of most plants, plays important roles in structural organization of plant cell walls and regulation of growth and development. Recent research in structural characterization of XyGs from different plant species revealed the diversification of XyG during plant evolution. This paper reviews progress in studies of glycosyltransferase genes involved in XyG biosynthesis. Most of the XyG-specific glycosyltransferases have been identified, and some of them appear to form a complex for involvement in XyG biosynthesis. We discuss how changes in XyG structure affect plant growth and development.

拟南芥中有3个参与木葡聚糖侧链合成的基因, 即MUR3 (MURUS3)、XLT2和XUT1 (xyloglucan- specific galacturonosyltransferase 1)。进化分析显示这3个基因彼此高度同源, 都位于GT47家族的同一个分支上(图2)。它们都转移糖基到木聚糖基的O-2位置, 但专一性不同, 拟南芥MUR3特异地转移半乳糖基到木葡聚糖的第3个木糖基上, 分别催化XXXG和XLXG为XXLG和XLLG; 而拟南芥XLT2特异地转移半乳糖基到木葡聚糖的第2个木糖基上, 分别催化XXXG和XXLG为XLXG和XLLG (Madson, 2003; Li et al., 2004; Jensen et al., 2012)。XUT1编码的半乳糖醛酸转移酶则催化形成β-D-GalpA-1,2-a-D-Xylp支链, 由于XUT1仅在根毛中特异表达, 因此最早被命名为ROOT HAIR SPECIFIC8 (RHS8)。进一步对XUT1 T-DNA插入突变体的研究表明, 当该基因缺失后, 拟南芥根毛的正常伸长受到抑制, 表明XUT1参与合成的这种酸性木葡聚糖结构Y在根毛细胞的延伸过程中起重要作用(Peña et al., 2012)。