Biotechnology of Natural Products, Technische Universität München, Liesel-Beckmann-Str. 1, 85354 Freising, Germany.
Institute for Biology I, RWTH Aachen University, Worringer Weg 3, 52074 Aachen, Germany.
Sci Rep. 2017 Mar 22;7:45113. doi: 10.1038/srep45113.
Strawberry fruits (Fragaria vesca) are valued for their sweet fruity flavor, juicy texture, and characteristic red color caused by anthocyanin pigments. To gain a deeper insight into the regulation of anthocyanin biosynthesis, we performed comparative metabolite profiling and transcriptome analyses of one red-fruited and two natural white-fruited strawberry varieties in two tissues and three ripening stages. Developing fruit of the three genotypes showed a distinctive pattern of polyphenol accumulation already in green receptacle and achenes. Global analysis of the transcriptomes revealed that the ripening process in the white-fruited varieties is already affected at an early developmental stage. Key polyphenol genes showed considerably lower transcript levels in the receptacle and achenes of both white genotypes, compared to the red genotype. The expression of the anthocyanidin glucosyltransferase gene and a glutathione S-transferase, putatively involved in the vacuolar transport of the anthocyanins, seemed to be critical for anthocyanin formation. A bHLH transcription factor is among the differentially expressed genes as well. Furthermore, genes associated with flavor formation and fruit softening appear to be coordinately regulated and seem to interact with the polyphenol biosynthesis pathway. This study provides new information about polyphenol biosynthesis regulators in strawberry, and reveals genes unknown to affect anthocyanin formation.
草莓果实（Fragaria vesca）因其甜美的水果风味、多汁的质地和由类黄酮色素引起的特征性红色而备受重视。为了更深入地了解花色苷生物合成的调控机制，我们对一个红色果实和两个天然白色果实的草莓品种在两个组织和三个成熟阶段进行了比较代谢组学和转录组学分析。三种基因型的发育果实已经在绿色花托和瘦果中表现出明显的多酚积累模式。对转录组的全面分析表明，白色品种的成熟过程在早期发育阶段就已经受到影响。与红色基因型相比，关键的多酚基因在白色两种基因型的花托和瘦果中的转录水平要低得多。花色苷葡萄糖基转移酶基因和谷胱甘肽 S-转移酶的表达，可能参与花色苷的液泡运输，似乎对花色苷的形成至关重要。bHLH 转录因子也是差异表达基因之一。此外，与风味形成和果实软化相关的基因似乎被协调调控，并与类黄酮生物合成途径相互作用。本研究提供了草莓中多酚生物合成调控因子的新信息，并揭示了一些未知的影响花色苷形成的基因。
