Accumulation of stilbene compounds and induction of related gene expression by hairy vetch and ryegrass extracts in grape berries

The present study investigated the accumulation of stilbene compounds ( trans - and cis -resveratrol, piceides, and piceatannol) and induction of gene expression related to their synthesis in the berries of ‘Campbell Early’ and ‘Kyoho’ grapes following treatment with water-based shoot extracts from hairy vetch and ryegrass. Trans -resveratrol was present in substantial amounts (4.1 ± 0.0 to 5.3 ± 0.07 μg/g fresh weight) in ‘Campbell Early’ and (7.6 ± 1.24 to 10.4 ± 0.35 07 μg/g fresh weight) in ‘Kyoho’, whereas trace amounts of cis -resveratrol were detected in treated grape berries. Moreover, the concentration of piceid and piceatannol in berries of both cultivars was markedly enhanced in response to treatment with plant extracts. Accumulation of stilbene compounds in berries increased at 24 h after treatment with the test extracts. Moreover, berries treated with extracts showed increased transcript levels of genes encoding enzymes involved in stilbene compound biosynthesis. Changes in the content of stilbene compounds were correlated with levels of stilbene synthase mRNA, indicating transcriptional control of stilbene synthase activity. Additionally, pre-treatment with the tested extracts resulted in reduced lesion size in berries inoculated with Botrytis cinerea . These results suggest that hairy vetch/ryegrass extracts can be used to elicit resistance responses against pathogen infection in grape berries.