Moore Katie L, Tosi Paola, Palmer Richard, Hawkesford Malcolm J, Grovenor Chris R M, Shewry Peter R
School of Materials, University of Manchester, Manchester, UK.
School of Agriculture Policy and Development, Reading University, Reading, UK.
Plant Biotechnol J. 2016 Sep;14(9):1876-82. doi: 10.1111/pbi.12549. Epub 2016 Mar 15.
Wheat is a major source of protein in the diets of humans and livestock but we know little about the mechanisms that determine the patterns of protein synthesis in the developing endosperm. We have used a combination of enrichment with (15) N glutamine and NanoSIMS imaging to establish that the substrate required for protein synthesis is transported radially from its point of entrance in the endosperm cavity across the starchy endosperm tissues, before becoming concentrated in the cells immediately below the aleurone layer. This transport occurs continuously during grain development but may be slower in the later stages. Although older starchy endosperm cells tend to contain larger protein deposits formed by the fusion of small protein bodies, small highly enriched protein bodies may also be present in the same cells. This shows a continuous process of protein body initiation, in both older and younger starchy endosperm cells and in all regions of the tissue. Immunolabeling with specific antibodies shows that the patterns of enrichment are not related to the contents of gluten proteins in the protein bodies. In addition to providing new information on the dynamics of protein deposition, the study demonstrates the wider utility of NanoSIMS and isotope labelling for studying complex developmental processes in plant tissues.
小麦是人类和牲畜饮食中蛋白质的主要来源，但我们对决定发育中的胚乳中蛋白质合成模式的机制知之甚少。我们结合使用（15）N谷氨酰胺富集和纳米二次离子质谱成像技术，确定蛋白质合成所需的底物从胚乳腔的入口点径向运输穿过淀粉胚乳组织，然后集中在糊粉层下方紧邻的细胞中。这种运输在籽粒发育过程中持续发生，但在后期可能会变慢。尽管较老的淀粉胚乳细胞往往含有由小蛋白质体融合形成的较大蛋白质沉积物，但相同细胞中也可能存在高度富集的小蛋白质体。这表明在较老和较年轻的淀粉胚乳细胞以及组织的所有区域中，蛋白质体的起始过程是连续的。用特异性抗体进行免疫标记表明，富集模式与蛋白质体中的面筋蛋白含量无关。除了提供有关蛋白质沉积动态的新信息外，该研究还证明了纳米二次离子质谱和同位素标记在研究植物组织复杂发育过程中的更广泛用途。
