Grey mold, Botrytis cinerea, is one of the most important fungal pathogens. It is estimated to cause losses of over £88 million per year in the UK tomato and cut flower industries alone, due to high fungicide cost, reduced yield and quality of produce. Broad host range, quiescent life cycle and resistance to fungicides are main challenges of Bortytis control. An industrial-academic research partnership was therefore formed to develop commercially applicable, non-chemical method to control Botrytis in pre-harvest environments.
The method is based on the principle of hormesis, where a beneficial effect (biotic stress tolerance) results from exposure to low doses of an agent (UV light) that is otherwise toxic or lethal at higher doses. It consists of short pulses of extremely high intensity broad spectrum light (UV-VIS-IR) applied to vegetative part of tomato plant. Light treatment elicits stress responses leading to increased plant defenses in subsequent Botrytis inoculation and reduced disease symptoms. We have optimized the dose of pulsed light to induce maximum resistance and minimum or no damage to the plants. The disease progression in treated plants was reduced by 25-40%. We determined the longevity of light induced resistance and tested its applicability in different tomato cultivars. The method is being validated in production tomato greenhouse where Botrytis control and effect on yield are tested on a large scale.
To understand the molecular basis of pulsed light induced resistance we have performed transcriptome analysis (RNA-seq) of treated plants different at time points following the light treatment. Additionally, response to Botrytis inoculation was compared between treated and control plants. Involvement of ROS and ethylene signaling in light induced resistance was highlighted.
Here developed technique could present environmentally friendly, sustainable, zero residue alternative to Botrytis control in industrial horticulture.