Regulation of Anthocyanin Biosynthesis by Drought and UV-B Radiation in Wild Tomato (Solanum peruvianum) Fruit

Anthocyanins are plant pigments derived from the phenylpropanoid pathway which are produced in many different species, contributing to defense against stresses by their antioxidant properties. Cultivated tomatoes cannot synthesize flavonoids; however, wild tomatoes such as Solanum chilense and Solanum lycopersicoides have anthocyanin pigmented skin. Other wild tomato species such as Solanum peruvianum have been poorly studied concerning anthocyanin accumulation in the fruit. This research is the first to address the regulation of anthocyanin biosynthesis mediated by drought stress and light radiation in S. peruvianum fruit. Transcript accumulation of SpAN2, encoding for a key MYB type transcription factor for the regulation of anthocyanin biosynthesis, was induced in the fruit of plants exposed to drought treatment. In addition, fruit peel accumulates a greater anthocyanin content in water deficit-treated plants. The expression of SpAN2 was also regulated according to sunlight exposure, reaching a higher expression during maximal daily UV radiation and under controlled UV-B treatments. Similar results were observed for the expression of the late flavonoid biosynthetic gene dihydroflavonol 4-reductase (SpDFR). These results suggest that SpAN2 and SpDFR are involved in anthocyanin biosynthesis under drought stress and UV radiation in S. peruvianum.

Automated summary

This research investigates the regulation of anthocyanin biosynthesis in S. peruvianum fruit under drought stress and light radiation. It found that drought treatment induces the expression of SpAN2 and leads to increased anthocyanin accumulation in the fruit peel. Additionally, sunlight exposure and UV-B treatments also regulate the expression of SpAN2 and the late flavonoid biosynthetic gene SpDFR.