Mannan is a class of cell wall polysaccharides widespread in the plant kingdom. Mannan structure and properties vary according to species and organ. The cell walls of cereal grains have been extensively studied due to their role in cereal processing and to their beneficial effect on human health as dietary fiber. Recently, we showed that mannan in wheat (Triticum aestivum) grain endosperm has a linear structure of β-1,4-linked mannose residues. The aim of this work was to study the biosynthesis and function of wheat grain mannan. We showed that mannan is deposited in the endosperm early during grain development, and we identified candidate mannan biosynthetic genes expressed in the endosperm. The functional study in wheat was unsuccessful therefore our best candidate genes were expressed in heterologous systems. The endosperm-specificTaCslA12 gene expressed in Pichia pastoris and in an Arabidopsis thaliana mutant depleted in glucomannan led to the production of wheat-like linear mannan lacking glucose residues and with moderate acetylation. Therefore, this gene encodes a mannan synthase and is likely responsible for the synthesis of wheat endosperm mannan.

中文翻译：

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小麦籽粒胚乳中表达的TaCslA12基因在酵母和拟南芥中表达时可合成小麦样甘露聚糖


甘露聚糖是一类广泛存在于植物界的细胞壁多糖。甘露聚糖的结构和性质因物种和器官而异。由于谷物细胞壁在谷物加工中的作用以及作为膳食纤维对人类健康的有益作用，谷物细胞壁已被广泛研究。最近，我们发现小麦（Triticum aestivum）籽粒胚乳中的甘露聚糖具有β-1,4-连接的甘露糖残基的线性结构。本工作的目的是研究小麦籽粒甘露聚糖的生物合成和功能。我们发现甘露聚糖在谷物发育早期沉积在胚乳中，并且我们鉴定了在胚乳中表达的候选甘露聚糖生物合成基因。小麦的功能研究不成功，因此我们最好的候选基因在异源系统中表达。在毕赤酵母和耗尽葡甘露聚糖的拟南芥突变体中表达的胚乳特异性TaCslA12基因导致产生缺乏葡萄糖残基且具有中等乙酰化的类似小麦的线性甘露聚糖。因此，该基因编码甘露聚糖合酶并且可能负责小麦胚乳甘露聚糖的合成。