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Article|01 Feb 2021|OPEN
R2R3-MYB transcription factors, StmiR858 and sucrose mediate potato flavonol biosynthesis
Sen Lin1, Rajesh K. Singh1,2, Moehninsi1 & Duroy A. Navarre1,3,
1Irrigated Agriculture Research and Extension Center, Washington State University, Prosser, WA, USA
2Present address: Department of Biotechnology, CSIR-Institute of Himalayan Bioresource Technology, Palampur, Himachal Pradesh 176061, India
3USDA-Agricultural Research Service, Prosser, WA, USA

Horticulture Research 8,
Article number: 25 (2021)
doi: 10.1038/hortres.2021.25
Views: 283

Received: 07 Jul 2020
Revised: 20 Nov 2020
Accepted: 23 Nov 2020
Published online: 01 Feb 2021

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.