The starchy endosperm of the mature wheat grain comprises three major cell types, namely sub-aleurone cells, prismatic cells and central cells, which differ in their contents of functional components: gluten proteins, starch, cell wall polysaccharides (dietary fibre) and lipids. Gradients are established during grain development but may be modified during grain maturation and are affected by plant nutrition, particularly nitrogen application, and environmental factors. Although the molecular controls of their formation are unknown, the high content of protein and low content of starch of sub-aleurone cells, compared to the other starchy endosperm cells types, may result from differences in developmental programming related to the cells having a separate origin (from anticlinal division of the aleurone cells). The gradients within the grain may be reflected in differences in the compositions of mill streams, particularly those streams enriched in the central and outer cells of the starchy endosperm, respectively, allowing the production of specialist flours for specific end uses.

中文翻译：

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小麦籽粒淀粉胚乳功能成分的空间分布


成熟小麦籽粒的淀粉胚乳包括三种主要细胞类型，即亚糊粉细胞、棱柱细胞和中央细胞，其功能成分含量不同：面筋蛋白、淀粉、细胞壁多糖（膳食纤维）和脂质。梯度是在谷物发育过程中建立的，但在谷物成熟过程中可能会发生变化，并受到植物营养（特别是氮肥施用）和环境因素的影响。尽管其形成的分子控制尚不清楚，但与其他淀粉胚乳细胞类型相比，亚糊粉层细胞的高蛋白质含量和低淀粉含量可能是由于与具有单独起源的细胞相关的发育程序的差异造成的（来自糊粉细胞的垂垂分裂）。谷物内的梯度可能反映在研磨流的成分差异上，特别是那些分别富含淀粉胚乳的中心和外细胞的流，从而允许生产用于特定最终用途的专用面粉。