Liu Lifeng, Paulitz Jonathan, Pauly Markus
Energy Biosciences Institute (L.L., J.P., M.P.) andDepartment of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720.
Energy Biosciences Institute (L.L., J.P., M.P.) andDepartment of Plant and Microbial Biology (M.P.), University of California, Berkeley, California 94720
Plant Physiol. 2015 Jun;168(2):549-60. doi: 10.1104/pp.15.00441. Epub 2015 Apr 13.
The predominant structure of the hemicellulose xyloglucan (XyG) found in the cell walls of dicots is a fucogalactoXyG with an XXXG core motif, whereas in the Poaceae (grasses and cereals), the structure of XyG is less xylosylated (XXGGn core motif) and lacks fucosyl residues. However, specialized tissues of rice (Oryza sativa) also contain fucogalactoXyG. Orthologous genes of the fucogalactoXyG biosynthetic machinery of Arabidopsis (Arabidopsis thaliana) are present in the rice genome. Expression of these rice genes, including fucosyl-, galactosyl-, and acetyltransferases, in the corresponding Arabidopsis mutants confirmed their activity and substrate specificity, indicating that plants in the Poaceae family have the ability to synthesize fucogalactoXyG in vivo. The data presented here provide support for a functional conservation of XyG structure in higher plants.
在双子叶植物细胞壁中发现的半纤维素木葡聚糖（XyG）的主要结构是具有XXXG核心基序的岩藻糖基半乳糖木葡聚糖，而在禾本科植物（草类和谷类）中，XyG的结构木糖基化程度较低（XXGGn核心基序）且缺乏岩藻糖基残基。然而，水稻（Oryza sativa）的特化组织中也含有岩藻糖基半乳糖木葡聚糖。水稻基因组中存在拟南芥（Arabidopsis thaliana）岩藻糖基半乳糖木葡聚糖生物合成机制的直系同源基因。这些水稻基因，包括岩藻糖基转移酶、半乳糖基转移酶和乙酰转移酶，在相应的拟南芥突变体中的表达证实了它们的活性和底物特异性，表明禾本科植物具有在体内合成岩藻糖基半乳糖木葡聚糖的能力。本文提供的数据支持了高等植物中XyG结构的功能保守性。
