Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas 78712.
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing 210095, China.
Plant Cell. 2020 Dec;32(12):3706-3722. doi: 10.1105/tpc.20.00320. Epub 2020 Sep 30.
Heterosis or hybrid vigor is widespread in plants and animals. Although the molecular basis for heterosis has been extensively studied, metabolic and proteomic contributions to heterosis remain elusive. Here we report an integrative analysis of time-series metabolome and proteome data in maize () hybrids and their inbred parents. Many maize metabolites and proteins are diurnally regulated, and many of these show nonadditive abundance in the hybrids, including key enzymes and metabolites involved in carbon assimilation. Compared with robust trait heterosis, metabolic heterosis is relatively mild. Interestingly, most amino acids display negative mid-parent heterosis (MPH), i.e., having lower values than the average of the parents, while sugars, alcohols, and nucleoside metabolites show positive MPH. From the network perspective, metabolites in the photosynthetic pathway show positive MPH, whereas metabolites in the photorespiratory pathway show negative MPH, which corresponds to nonadditive protein abundance and enzyme activities of key enzymes in the respective pathways in the hybrids. Moreover, diurnally expressed proteins that are upregulated in the hybrids are enriched in photosynthesis-related gene-ontology terms. Hybrids may more effectively remove toxic metabolites generated during photorespiration, and thus maintain higher photosynthetic efficiency. These metabolic and proteomic resources provide unique insight into heterosis and its utilization for high yielding maize and other crop plants.
杂种优势或杂种优势在动植物中普遍存在。尽管杂种优势的分子基础已经得到了广泛的研究，但代谢和蛋白质组学对杂种优势的贡献仍然难以捉摸。在这里，我们报告了对玉米（）杂种及其自交亲本的时间序列代谢组和蛋白质组数据的综合分析。许多玉米代谢物和蛋白质是昼夜节律调节的，其中许多在杂种中表现出非加性丰度，包括参与碳同化的关键酶和代谢物。与稳健的性状杂种优势相比，代谢杂种优势相对温和。有趣的是，大多数氨基酸表现出负的中亲杂种优势（MPH），即低于双亲的平均值，而糖、醇和核苷代谢物则表现出正的 MPH。从网络的角度来看，光合作用途径中的代谢物表现出正的 MPH，而光呼吸途径中的代谢物表现出负的 MPH，这与杂种中相应途径的非加性蛋白质丰度和关键酶的酶活性相对应。此外，在杂种中上调表达的昼夜表达蛋白在光合作用相关的基因本体论术语中富集。杂种可能更有效地清除光呼吸过程中产生的有毒代谢物，从而保持更高的光合作用效率。这些代谢和蛋白质组学资源为杂种优势及其在高产玉米和其他作物中的利用提供了独特的见解。
