Quantitative Multilevel Analysis of Central Metabolism in Developing Oilseeds of Oilseed Rape during in Vitro Culture
Quantitative Multilevel Analysis of Central Metabolism in Developing Oilseeds of Oilseed Rape during in Vitro Culture
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DOI：
10.1104/pp.15.00385
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发表时间：
2015-07-01
期刊：
影响因子：
7.4
通讯作者：
Rolletschek, Hardy
中科院分区：
文献类型：
--
作者：
Schwender, Joerg;Hebbelmann, Inga;Rolletschek, Hardy
种子是许多食品、饲料和燃料产品的基础。种子产量、成分和质量的持续提高需要更好地理解发育中的种子如何将碳和氮供应转化为储存。目前对这一过程的了解通常基于这样的前提，即转录调控通过酶浓度直接转化为通量。为了突出代谢控制，我们探讨了油菜（Brassica napus）离体培养发育胚碳分配的基因型差异。我们确定的生物量组成，以及79净通量，77种代谢产物的水平，和26种酶的活性，特别注重在9个选定的种质资源的中央代谢。总的来说，我们观察到的生物质组成部分的脂质和淀粉之间的权衡。随着基因型谱中脂质含量的增加，质体脂肪酸合成和糖酵解通量随之增加，而糖酵解中间产物减少。脂质/淀粉的权衡没有反映在蛋白质组水平，指出（翻译后）代谢控制的意义。酶活性/流量和代谢产物/流量的相关性表明，质体丙酮酸激酶发挥流量控制和脂质/淀粉的权衡是最有可能介导的磷酸果糖激酶和ADP-葡萄糖焦磷酸化酶的变构反馈调节。定量数据还用于计算体内质量作用比、反应平衡和代谢物周转时间。化合物如环状3 '，5'-AMP和蔗糖-6-磷酸被鉴定为可能参与迄今未知的代谢控制机制。本研究为中枢代谢的研究提供了丰富的定量数据来源。
Seeds provide the basis for many food, feed, and fuel products. Continued increases in seed yield, composition, and quality require an improved understanding of how the developing seed converts carbon and nitrogen supplies into storage. Current knowledge of this process is often based on the premise that transcriptional regulation directly translates via enzyme concentration into flux. In an attempt to highlight metabolic control, we explore genotypic differences in carbon partitioning for in vitro cultured developing embryos of oilseed rape (Brassica napus). We determined biomass composition as well as 79 net fluxes, the levels of 77 metabolites, and 26 enzyme activities with specific focus on central metabolism in nine selected germplasm accessions. Overall, we observed a tradeoff between the biomass component fractions of lipid and starch. With increasing lipid content over the spectrum of genotypes, plastidic fatty acid synthesis and glycolytic flux increased concomitantly, while glycolytic intermediates decreased. The lipid/starch tradeoff was not reflected at the proteome level, pointing to the significance of (posttranslational) metabolic control. Enzyme activity/flux and metabolite/flux correlations suggest that plastidic pyruvate kinase exerts flux control and that the lipid/starch tradeoff is most likely mediated by allosteric feedback regulation of phosphofructokinase and ADP-glucose pyrophosphorylase. Quantitative data were also used to calculate in vivo mass action ratios, reaction equilibria, and metabolite turnover times. Compounds like cyclic 3',5'-AMP and sucrose-6-phosphate were identified to potentially be involved in so far unknown mechanisms of metabolic control. This study provides a rich source of quantitative data for those studying central metabolism.