Controlled application of abiotic stress to induce production of valuable specialized metabolites in bell pepper leaves

Abstract

The interdisciplinary project TaReCa aims at identifying abiotic stress treatments to induce increased accumulation of valuable flavonoids in green plant biomass of bell pepper after the last fruit harvest in commercial greenhouses for extraction and industrial utilization. To identify suitable abiotic stresses for induction of flavonoids, different intensities and durations of salt and cold stress treatments were tested with young bell pepper plants. With a combination of salt (200 mmol/L) and cold (18/12 °C day/night) stress, applied for 14 days, we were able to increase total phenolics and flavonoids contents 2- and 4-fold in leaves of young bell pepper plants of two commercially grown lines (cv. Mazurka, cv. Stayer). In addition, target flavonoid metabolites graveobioside A and cynaroside were strongly accumulated in both lines, leading to a 3- and 13-fold induction in leaves of cv. Mazurka. Phenotyping methods based on leaf color and assessment of leaf fluorescence were used to monitor plant stress responses and to develop an easy-to-use method to predict changes in leaf flavonoid or target metabolite content in production greenhouses. This novel approach of valorization of horticultural side-streams has the potential to add value to the bell pepper production