Zhang Wei, Zhang Mingyi, Zhu Xianwen, Cao Yaping, Sun Qing, Ma Guojia, Chao Shiaoman, Yan Changhui, Xu Steven S, Cai Xiwen
Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA.
Department of Computer Science, North Dakota State University, Fargo, ND, 58108-6050, USA.
Theor Appl Genet. 2018 Feb;131(2):365-375. doi: 10.1007/s00122-017-3007-0. Epub 2017 Nov 1.
This work pinpointed the goatgrass chromosomal segment in the wheat B genome using modern cytogenetic and genomic technologies, and provided novel insights into the origin of the wheat B genome. Wheat is a typical allopolyploid with three homoeologous subgenomes (A, B, and D). The donors of the subgenomes A and D had been identified, but not for the subgenome B. The goatgrass Aegilops speltoides (genome SS) has been controversially considered a possible candidate for the donor of the wheat B genome. However, the relationship of the Ae. speltoides S genome with the wheat B genome remains largely obscure. The present study assessed the homology of the B and S genomes using an integrative cytogenetic and genomic approach, and revealed the contribution of Ae. speltoides to the origin of the wheat B genome. We discovered noticeable homology between wheat chromosome 1B and Ae. speltoides chromosome 1S, but not between other chromosomes in the B and S genomes. An Ae. speltoides-originated segment spanning a genomic region of approximately 10.46 Mb was detected on the long arm of wheat chromosome 1B (1BL). The Ae. speltoides-originated segment on 1BL was found to co-evolve with the rest of the B genome. Evidently, Ae. speltoides had been involved in the origin of the wheat B genome, but should not be considered an exclusive donor of this genome. The wheat B genome might have a polyphyletic origin with multiple ancestors involved, including Ae. speltoides. These novel findings will facilitate genome studies in wheat and other polyploids.
这项研究利用现代细胞遗传学和基因组技术确定了小麦B基因组中的节节麦染色体片段，为小麦B基因组的起源提供了新的见解。小麦是一种典型的异源多倍体，具有三个同源亚基因组（A、B和D）。亚基因组A和D的供体已被确定，但亚基因组B的供体尚未确定。节节麦（基因组为SS）一直被争议性地认为可能是小麦B基因组的供体候选者。然而，节节麦S基因组与小麦B基因组之间的关系仍 largely obscure。本研究采用综合细胞遗传学和基因组学方法评估了B和S基因组的同源性，并揭示了节节麦对小麦B基因组起源的贡献。我们发现小麦1B染色体与节节麦1S染色体之间存在显著同源性，但B和S基因组的其他染色体之间不存在同源性。在小麦1B染色体（1BL）长臂上检测到一个起源于节节麦的片段，其跨越约10.46 Mb的基因组区域。发现1BL上起源于节节麦的片段与B基因组的其余部分共同进化。显然，节节麦参与了小麦B基因组的起源，但不应被视为该基因组的唯一供体。小麦B基因组可能具有多系起源，涉及多个祖先，包括节节麦。这些新发现将促进小麦和其他多倍体的基因组研究。
