Wheat progenitors metagenome using bacterial, fungal, eukaryotic and oomycetes targeted primers. Wheat metagenome

Modern hexaploid bread wheat has been derived by human selection from at least 3 diploid ancestors. We sought to understand the effects of this domestication on the rhizosphere microbiome by recapitulating the hybridization event, which occurred over the last ten thousand years with the formation of synthetic hexaploid wheat (SHW) by introducing the DD genome of Aegilops tauschii into tetraploid Triticum durum. The rhizosphere communities of 22 wheat accessions (wild: T. dicoccoides, Ae. tauschii, modern: T. aestivum, T. durum, and synthetic: Synthetic Hybrid Wheat lines (SHW) and back-cross lines (BC)) were then analyzed. Major differences occurred in the prokaryotic community between bulk soil and the rhizosphere of different plants, with subtler differences in the eukaryotic community. AM fungi (Glomeromycota) were present in all wheat lines, but especially abundant in the diploid Ae. tauschii. The fungal communities of the synthetic hexaploid lines were more similar to the parental species Ae. tauschii than to the other hexaploid lines, indicating the DD genome plays a major role in selection of several fungal genera and Nematoda. Furthermore, domestication has influenced the contribution of the DD genome on the selection of the wheat microbiome indicating it is at least partly under plant genetic control. Understanding this is an important first step in incorporating the soil microbiome into plant breeding.

现代六倍体面包小麦经人类选育驯化，起源于至少3个二倍体祖先物种。本研究通过重现这一发生在近万年间的杂交事件——即通过将节节麦（Aegilops tauschii）的DD基因组导入四倍体硬粒小麦（Triticum durum）中以构建合成六倍体小麦（Synthetic Hybrid Wheat, SHW）——旨在解析此次驯化过程对根际微生物组的影响。随后，研究人员对22份小麦种质材料的根际群落进行了分析，其中野生材料包括野生二粒小麦（T. dicoccoides）、节节麦（Ae. tauschii）；现代栽培材料包括普通小麦（T. aestivum）、硬粒小麦（T. durum）；合成材料包括合成六倍体小麦品系（SHW）与回交品系（back-cross lines, BC）。原核生物群落在非根际土壤与不同植株根际间存在显著差异，而真核生物群落的差异则相对微弱。丛枝菌根真菌（AM fungi, 球囊菌门Glomeromycota）在所有小麦品系中均有分布，但在二倍体节节麦Ae. tauschii中丰度尤高。合成六倍体小麦品系的真菌群落与其亲本物种节节麦的相似度，高于与其他六倍体小麦品系的相似度，这表明DD基因组在多个真菌属与线虫动物门（Nematoda）类群的筛选中发挥了核心作用。此外，驯化过程影响了DD基因组对小麦微生物组的筛选贡献，这说明小麦微生物组至少部分受植物遗传调控。解析这一机制，是将土壤微生物组纳入植物育种体系的重要第一步。