Plant Breeding, Wageningen University and Research, Droevendaalsesteeg 1, NL-6708 PB Wageningen, the Netherlands.
The John Bingham Laboratory, NIAB, 93 Lawrence Weaver Road, Cambridge, CB3 0LE, UK.
Plant J. 2021 Apr;106(1):86-94. doi: 10.1111/tpj.15147. Epub 2021 Feb 19.
Most alpha-gliadin genes of the Gli-D2 locus on the D genome of hexaploid bread wheat (Triticum aestivum) encode for proteins with epitopes that can trigger coeliac disease (CD), and several contain a 33-mer peptide with six partly overlapping copies of three epitopes, which is regarded as a remarkably potent T-cell stimulator. To increase genetic diversity in the D genome, synthetic hexaploid wheat lines are being made by hybridising accessions of Triticum turgidum (AB genome) and Aegilops tauschii (the progenitor of the D genome). The diversity of alpha-gliadins in A. tauschii has not been studied extensively. We analysed the alpha-gliadin transcriptome of 51 A. tauschii accessions representative of the diversity in A. tauschii. We extracted RNA from developing seeds and performed 454 amplicon sequencing of the first part of the alpha-gliadin genes. The expression profile of allelic variants of the alpha-gliadins was different between accessions, and also between accessions of the Western and Eastern clades of A. tauschii. Generally, both clades expressed many allelic variants not found in bread wheat. In contrast to earlier studies, we detected the 33-mer peptide in some A. tauschii accessions, indicating that it was introduced along with the D genome into bread wheat. In these accessions, transcripts with the 33-mer peptide were present at lower frequencies than in bread wheat varieties. In most A. tauschii accessions, however, the alpha-gliadins do not contain the epitope, and this may be exploited, through synthetic hexaploid wheats, to breed bread wheat varieties with fewer or no coeliac disease epitopes.
大多数六倍体普通小麦（Triticum aestivum）D 基因组 Gli-D2 位点的α-醇溶蛋白基因编码具有引发乳糜泻（CD）表位的蛋白质，并且几个基因含有一个 33 个氨基酸的肽，其中包含六个重叠的三个表位的部分拷贝，被认为是一种非常有效的 T 细胞刺激物。为了增加 D 基因组的遗传多样性，正在通过杂交普通小麦（AB 基因组）和粗山羊草（D 基因组的祖先后代）的品系来制造合成的六倍体小麦品系。粗山羊草的α-醇溶蛋白多样性尚未得到广泛研究。我们分析了 51 个粗山羊草品系的α-醇溶蛋白转录组，这些品系代表了粗山羊草的多样性。我们从发育中的种子中提取 RNA，并对α-醇溶蛋白基因的第一部分进行 454 扩增子测序。等位变体的表达谱α-醇溶蛋白在品系之间以及粗山羊草的西部和东部支系之间有所不同。通常，两个支系都表达了许多在普通小麦中找不到的等位变体。与早期的研究不同，我们在一些粗山羊草品系中检测到了 33 个氨基酸的肽，这表明它是与 D 基因组一起引入普通小麦的。在这些品系中，含有 33 个氨基酸的肽的转录本的频率低于普通小麦品种。然而，在大多数粗山羊草品系中，α-醇溶蛋白不包含该表位，这可以通过合成的六倍体小麦来利用，从而培育出含有较少或没有乳糜泻表位的普通小麦品种。
