|LIN, SEN - Washington State University|
|SINGH, RAJESH - Washington State University|
|HNINSI, MOE - Washington State University|
|Navarre, Duroy - Roy|
Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/24/2020
Publication Date: 2/1/2021
Citation: Lin, S., Singh, R., Hninsi, M., Navarre, D.A. 2021. R2R3-MYB transcription factors, StmiR858 and sucrose mediate potato flavonol biosynthesis. New Phytologist. 8. Article 25. https://doi.org/10.1038/s41438-021-00463-9.
Interpretive Summary: Crop performance is often limited by the types of natural compounds made or not made by the plant. One class of natural compounds are phenylpropanoids and plants can make thousands of different types. These compounds have diverse roles in plants, including in plant defenses, abiotic stress resistance and plant development. They are also dietarily desirable, having numerous health-promoting effects including in cardiovascular health, gut health, mental acuity, longevity and they can be anti-inflammatory. Some potatoes contain much higher amounts of these compounds than others, but the reasons for the differences are not fully understood. Scientists at Washington State University and ARS scientists in Prosser, WA discovered several factors that control the type and amount of phenylpropanoids in potatoes. These factors include transcription factors, a microRNA and sucrose. A better understanding of what controls the types and amounts of phenylpropanoids in potatoes will allow the development of potatoes that have optimized content, for both crop performance and human health.
Technical Abstract: 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