Flavonols and other phenylpropanoids protect plants from biotic and abiotic stress and are dietarily desirable because of their health-promoting properties. The ability to develop new potatoes (Solanum tuberosum) with optimal types and amounts of phenylpropanoids is limited by lack of knowledge about the regulatory mechanisms. Exogenous sucrose increased flavonols, whereas overexpression of the MYB StAN1 induced sucrolytic gene expression. Heterologous StAN1 protein bound promoter fragments from sucrolytic genes (SUSY1 and INV1). Two additional MYBs and one microRNA were identified that regulated potato flavonols. Overexpression analysis showed MYB12A and C increased amounts of flavonols and other phenylpropanoids. Endogenous flavonol amounts in light-exposed organs were much higher those in the dark. Expression levels of StMYB12A and C were high in flowers but low in tubers. Transient overexpression of miR858 altered potato flavonol metabolism. Endogenous StmiR858 expression was much lower in flowers than leaves and correlated with flavonol amounts in these organs. Collectively, these findings support the hypothesis that sucrose, MYBs, and miRNA control potato phenylpropanoid metabolism in a finely tuned manner that includes a feedback loop between sucrose and StAN1. These findings will aid in the development of potatoes with phenylpropanoid profiles optimized for crop performance and human health.

黄酮醇和其他苯丙烷类化合物可保护植物免受生物和非生物胁迫，并且由于它们具有促进健康的特性，因此在饮食上是合乎需要的。由于缺乏对调节机制的了解，限制了开发具有最佳类型和数量的苯丙烷类化合物的马铃薯（马铃薯）的能力。外源蔗糖增加了黄酮醇，而MYB StAN1的过表达诱导了糖分解基因的表达。异源StAN1蛋白结合了糖脂分解基因（SUSY1和INV1）的启动子片段。鉴定出另外两种MYB和一种microRNA可以调节马铃薯黄酮醇。过表达分析显示MYB12A和C黄酮醇和其他苯基丙烷的含量增加。光照器官中的内源性黄酮醇含量要高得多。StMYB12A和C的表达水平在花中较高，而在块茎中较低。miR858的瞬时过表达改变了马铃薯黄酮醇的代谢。花中的内源性StmiR858表达远低于叶，并且与这些器官中的黄酮醇含量相关。总的来说，这些发现支持以下假设：蔗糖，MYB和miRNA以微调的方式控制马铃薯苯丙烷的代谢，包括蔗糖和StAN1之间的反馈环。这些发现将有助于开发具有针对作物生长性能和人类健康而优化的苯丙氨酸类特征的马铃薯。