Optimization of light and temperature in indoor farming to boost anthocyanin biosynthesis and accumulation in Indigo Rose tomato

Abstract

Anthocyanins are a group of flavonoids that are found ubiquitously in fruits and vegetables. They act as antioxidants in plants and are considered to have potential benefits to human health. The tomato cultivar ‘Indigo Rose’ produces purple-skinned fruits that are rich in anthocyanins in fruit peel. The current study focussed on the detection of anthocyanins and examined the expression profiling of anthocyanin biosynthetic and regulatory genes in Indigo Rose fruits grown under semi-closed greenhouse and fully controlled growth chamber conditions. The anthocyanin content in Indigo Rose fruits grown under growth chamber conditions with a long-day photoperiod and ambient temperature was higher than those grown in the greenhouse with a short-day photoperiod and high temperature. Under indoor growth conditions, moderate to high intensity of artificial light (160−240 µmol m⁻² s⁻¹) and relatively low temperature (20−25 °C) promoted anthocyanin production and accumulation in Indigo Rose fruits. The comparative studies on gene expression under different growth conditions also demonstrate that the expression levels of the structural and regulatory genes in the anthocyanin biosynthetic pathway have a positive correlation with the anthocyanin content in the fruit peel. The growth conditions identified in this study could be used to grow Indigo Rose in indoor farming in Singapore, where the tropical climate makes it challenging to set up a tomato plantation in an open field or greenhouse.