Carrari Fernando, Baxter Charles, Usadel Björn, Urbanczyk-Wochniak Ewa, Zanor Maria-Ines, Nunes-Nesi Adriano, Nikiforova Victoria, Centero Danilo, Ratzka Antje, Pauly Markus, Sweetlove Lee J, Fernie Alisdair R
Max-Planck-Institut für Molekulare Pflanzenphysiologie, 14476 Golm-Postdam, Germany.
Plant Physiol. 2006 Dec;142(4):1380-96. doi: 10.1104/pp.106.088534. Epub 2006 Oct 27.
Tomato (Solanum lycopersicum) is a well-studied model of fleshy fruit development and ripening. Tomato fruit development is well understood from a hormonal-regulatory perspective, and developmental changes in pigment and cell wall metabolism are also well characterized. However, more general aspects of metabolic change during fruit development have not been studied despite the importance of metabolism in the context of final composition of the ripe fruit. In this study, we quantified the abundance of a broad range of metabolites by gas chromatography-mass spectrometry, analyzed a number of the principal metabolic fluxes, and in parallel analyzed transcriptomic changes during tomato fruit development. Metabolic profiling revealed pronounced shifts in the abundance of metabolites of both primary and secondary metabolism during development. The metabolite changes were reflected in the flux analysis that revealed a general decrease in metabolic activity during ripening. However, there were several distinct patterns of metabolite profile, and statistical analysis demonstrated that metabolites in the same (or closely related) pathways changed in abundance in a coordinated manner, indicating a tight regulation of metabolic activity. The metabolite data alone allowed investigations of likely routes through the metabolic network, and, as an example, we analyze the operational feasibility of different pathways of ascorbate synthesis. When combined with the transcriptomic data, several aspects of the regulation of metabolism during fruit ripening were revealed. First, it was apparent that transcript abundance was less strictly coordinated by functional group than metabolite abundance, suggesting that posttranslational mechanisms dominate metabolic regulation. Nevertheless, there were some correlations between specific transcripts and metabolites, and several novel associations were identified that could provide potential targets for manipulation of fruit compositional traits. Finally, there was a strong relationship between ripening-associated transcripts and specific metabolite groups, such as TCA-cycle organic acids and sugar phosphates, underlining the importance of the respective metabolic pathways during fruit development.
番茄（Solanum lycopersicum）是肉质果实发育和成熟过程中一个经过充分研究的模型。从激素调节的角度来看，番茄果实的发育已得到很好的理解，色素和细胞壁代谢的发育变化也得到了很好的表征。然而，尽管代谢在成熟果实的最终组成中具有重要意义，但果实发育过程中代谢变化的更普遍方面尚未得到研究。在本研究中，我们通过气相色谱 - 质谱法定量了多种代谢物的丰度，分析了一些主要的代谢通量，并同时分析了番茄果实发育过程中的转录组变化。代谢谱分析揭示了发育过程中初级和次级代谢物丰度的显著变化。代谢物的变化反映在通量分析中，该分析显示成熟过程中代谢活性普遍下降。然而，代谢物谱存在几种不同的模式，统计分析表明，同一（或密切相关）途径中的代谢物丰度以协调的方式变化，表明代谢活性受到严格调控。仅代谢物数据就允许研究通过代谢网络的可能途径，例如，我们分析了抗坏血酸合成不同途径的操作可行性。当与转录组数据结合时，揭示了果实成熟过程中代谢调节的几个方面。首先，很明显转录本丰度在功能组之间的协调不如代谢物丰度严格，这表明翻译后机制在代谢调节中占主导地位。尽管如此，特定转录本和代谢物之间存在一些相关性，并且鉴定出了几种新的关联，这些关联可为操纵果实组成性状提供潜在靶点。最后，成熟相关转录本与特定代谢物组之间存在很强的关系，例如三羧酸循环有机酸和糖磷酸酯，这强调了各自代谢途径在果实发育过程中的重要性。
