Tomato is an important economic crop all over the world. Volatile flavors in tomato fruit are key factors influencing consumer liking and commercial quality. However, the regulatory mechanism controlling the volatile flavors of tomatoes is still not clear. Here, we integrated the metabolome and transcriptome of the volatile flavors in tomato fruit to explore the regulatory mechanism of volatile flavor formation, using wild and cultivated tomatoes with significant differences in flavors. A total of 35 volatile flavor compounds were identified, based on the solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). The content of the volatiles, affecting fruit flavor, significantly increased in the transition from breaker to red ripe fruit stage. Moreover, the total content of the volatiles in wild tomatoes was much higher than that in the cultivated tomatoes. The content variations of all volatile flavors were clustered into 10 groups by hierarchical cluster and Pearson correlation analysis (PCC). The fruit transcriptome was also patterned into 10 groups, with significant variations both from the mature green to breaker fruit stage and from the breaker to red ripe fruit stage. Combining the metabolome and the transcriptome of the same developmental stage of fruits by co-expression analysis, we found that the expression level of 1 182 genes was highly correlated with the content of volatile flavor compounds, thereby constructing two regulatory pathways of important volatile flavors. One pathway is tetrahydrothiazolidine -hydroxylase ()-dependent, which is regulated by two transcription factors (TFs) from the bHLH and AP2/ERF families, controlling the synthesis of 2-isobutylthiazole in amino acid metabolism. The other is lipoxygenase ()-dependent, which is regulated by one TF from the HD-Zip family, controlling the synthesis of hexanal and ()-2-heptenal in fatty acid metabolism. Dual-luciferase assay confirmed the binding of bHLH and AP2/ERF to their structural genes. The findings of this study provide new insights into volatile flavor formation in tomato fruit, which can be useful for tomato flavor improvement.

中文翻译：

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转录组和代谢组的整合揭示了番茄果实成熟过程中挥发性风味形成的调节机制


番茄是全世界重要的经济作物。番茄果实中的挥发性风味是影响消费者喜好和商业质量的关键因素。然而，控制番茄挥发性风味的调控机制仍不清楚。在此，我们利用风味差异显着的野生和栽培番茄，整合番茄果实中挥发性风味物质的代谢组和转录组，探讨挥发性风味形成的调控机制。基于固相微萃取-气相色谱-质谱法(SPME-GC-MS)，共鉴定出35种挥发性风味化合物。影响果实风味的挥发物含量在果实从破壳期到红熟期的过渡期间显着增加。而且，野生番茄中挥发物的总含量远高于栽培番茄。通过层次聚类和皮尔逊相关分析（PCC）将所有挥发性风味物质的含量变化分为10组。果实转录组也分为 10 组，从成熟的绿色到破壳果阶段以及从破壳到红成熟果实阶段都有显着差异。通过共表达分析，结合水果同一发育阶段的代谢组和转录组，发现1 182个基因的表达水平与挥发性风味化合物的含量高度相关，从而构建了两条重要挥发性风味物质的调控通路。一种途径是四氢噻唑烷羟化酶 () 依赖性的，该途径受 bHLH 和 AP2/ERF 家族的两种转录因子 (TF) 调节，控制氨基酸代谢中 2-异丁基噻唑的合成。 另一种是脂氧合酶()依赖性的，由HD-Zip家族的一个TF调节，控制脂肪酸代谢中己醛和()-2-庚烯醛的合成。双荧光素酶测定证实了 bHLH 和 AP2/ERF 与其结构基因的结合。这项研究的结果为番茄果实中挥发性风味的形成提供了新的见解，这对于改善番茄风味很有用。