Inhibition of Botrytis cinerea and accumulation of stilbene compounds by light-emitting diodes of grapevine leaves and differential expression of defense-related genes

Grey mold (Botrytis cinerea) is one of the most common diseases to attack grapes, causing serious damage during grape production. In the present study, the effects of light-emitting diodes (LED) on the suppression of fungal growth, defense related gene expression and accumulation of stilbenic compounds were investigated. Irradiation with blue and red light inhibited lesion development relative to fluorescent light in detached leaves. Treatment of detached leaves with LED light, especially blue and red, resulted in accumulation of stilbenic compounds and differential expression of genes involved in defense response. Among five stilbenic compounds, concentrations of trans- and cis-piceid were higher than those of trans- and cis-resveratrol, as well as piceatannol in both 'Campbell Early' and 'Kyoho' leaves treated with blue and red light. The gene expression of beta-1,3 glucanase (Glu), osmotin (OSM), pathogen-related protein 4a (PR4a), protease inhibitor-like protein (PILP), thaumatin-like protein (TLP), glutathione-S-transferase (GST), phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), and stilbene synthase (STS) were highly upregulated under blue and red LED light. The results reported here will facilitate development of alternative methods to enhance the accumulation of resveratrol compound and protect grapevine from fungal pathogen infections.