Key laboratory of Molecular Epigenetics of Ministry of Education (MOE), Northeast Normal University, Changchun, 130024, China.
BMC Plant Biol. 2019 May 7;19(1):188. doi: 10.1186/s12870-019-1796-9.
The BBAA subgenomes of hexaploid common wheat are structurally intact, which makes it possible to extract the BBAA subgenomes to constitute a novel plant type, namely, extracted tetraploid wheat (ETW). ETW displays multiple abnormal phenotypes such as massively reduced biomass and abnormal spike development, compared to extant tetraploid wheat with a BBAA genome. The genetic, biochemical and physiological basis underlying the phenotypic abnormality of ETW remains unknown.
To explore the biochemical basis of these phenotypic abnormalities, we analysed the metabolomic and proteomic profiles and quantified 46 physiological traits of ETW in comparison with its common wheat donor (genome BBAADD), and a durum tetraploid wheat cultivar (genome BBAA). Among these three types of wheat, ETW showed a saliently different pattern of nutrient accumulation and seed quality, markedly lower concentrations of many metabolites involved in carbohydrate metabolism, and higher concentrations of many metabolites related to amino acids. Among the metabolites, changes in shikimate and sucrose were the most conspicuous. Higher levels of shikimate and lower levels of sucrose influence many metabolic processes including carbohydrate and amino acid metabolism, which may contribute to the phenotypic abnormalities. Gene expression assay showed downregulation of a shikimate degradation enzyme (5-enolpyruvylshikimate-3-phosphate synthase) coding gene and upregulation of several genes coding for the sucrose hydrolysis enzyme, which could explain the higher levels of shikimate and lower levels of sucrose, respectively.
Our results suggest that significant and irreversible biochemical changes have occurred in the BBAA subgenomes of common wheat during the course of its co-evolution with the DD subgenome at the hexaploid level.
六倍体普通小麦的 BBAA 亚基因组结构完整，这使得提取 BBAA 亚基因组构成新型植物类型（即提取的四倍体小麦，ETW）成为可能。与具有 BBAA 基因组的现存四倍体小麦相比，ETW 表现出多种异常表型，如生物量大幅减少和穗发育异常。ETW 表型异常的遗传、生化和生理基础尚不清楚。
为了探讨这些表型异常的生化基础，我们分析了 ETW 的代谢组学和蛋白质组学图谱，并与普通小麦供体（基因组 BBAADD）和硬粒小麦四倍体品种（基因组 BBAA）比较，量化了 46 种生理特性。在这三种小麦中，ETW 表现出明显不同的养分积累和种子质量模式，涉及碳水化合物代谢的许多代谢物浓度明显降低，许多与氨基酸相关的代谢物浓度较高。在这些代谢物中，莽草酸和蔗糖的变化最为明显。较高的莽草酸水平和较低的蔗糖水平影响许多代谢过程，包括碳水化合物和氨基酸代谢，这可能导致表型异常。基因表达分析表明，莽草酸降解酶（5-烯醇丙酮酰莽草酸-3-磷酸合酶）编码基因下调，蔗糖水解酶编码基因上调，这分别可以解释莽草酸水平升高和蔗糖水平降低的原因。
我们的结果表明，在普通小麦与 DD 亚基因组在六倍体水平共同进化的过程中，BBAA 亚基因组发生了显著且不可逆转的生化变化。
