College of Horticulture, Sichuan Agricultural University, Chengdu 611130, China.
Institute of Pomology & Olericulture, Sichuan Agricultural University, Chengdu 611130, China.
Int J Mol Sci. 2022 Jul 1;23(13):7375. doi: 10.3390/ijms23137375.
Anthocyanin content is important for both the external and internal fruit quality of cultivated strawberries, but the mechanism of its accumulation in pinkish-skinned and white-fleshed strawberries is puzzling. Here, we found that the factor determining variation in the flesh color was not the but the in the cultivated strawberry Benihoppe and its white-fleshed mutant Xiaobai. Compared with Benihoppe, there was no significant difference in the coding sequence and expression level of in Xiaobai's flesh. Instead, the transcription of was dramatically inhibited. The combined analyses of transcriptomics and metabolomics showed that the differential genes and metabolites were significantly enriched in the phenylpropanoid biosynthesis pathway. Furthermore, the transient overexpression of greatly restored anthocyanins' accumulation in Xiaobai's flesh and did not produce additional pigment species, as in Benihoppe. The transcriptional repression of was not directly caused by promoter methylations, lncRNAs, or microRNAs. In addition, the unexpressed , which resulted in the loss of cyanidin 3-O-glucoside in the flesh, was not due to methylation in promoters. Our findings suggested that the repression of was responsible for the natural formation of pinkish-skinned and white-fleshed strawberries.
花色苷含量对栽培草莓的外观和内在品质都很重要，但粉红皮白肉草莓中花色苷积累的机制仍令人费解。本研究发现，决定果肉颜色变异的不是 ，而是栽培草莓‘Benihoppe’及其白肉突变体‘Xiaobai’中的 。与‘Benihoppe’相比，‘Xiaobai’果肉中 的编码序列和表达水平没有显著差异。相反， 的转录水平被显著抑制。转录组学和代谢组学的综合分析表明，差异基因和代谢物在苯丙烷生物合成途径中显著富集。此外， 的瞬时过表达极大地恢复了‘Xiaobai’果肉中花色苷的积累，并且没有像‘Benihoppe’那样产生额外的色素种类。 转录抑制不是由启动子甲基化、lncRNA 或 microRNA 直接引起的。此外，未表达的 导致果肉中失去矢车菊素 3-O-葡萄糖苷，这也不是由于启动子甲基化造成的。本研究结果表明， 抑制是导致自然形成粉红皮白肉草莓的原因。
