Biologia 69/12: 1693—1700, 2014 Section Cellular and Molecular Biology DOI: 10.2478/s11756-014-0488-z Accumulation of stilbene compounds and induction of related gene expression by hairy vetch and ryegrass extracts in grape berries Md. Tariqul Islam, Soon-Young Ahn, Md. Zaherul Islam, Seon Ae Kim & Hae Keun Yun* Department of Horticultural Science, Yeungnam University, Gyeongsan 712-749, Republic of Korea; e-mail: haekeun@ynu.ac.kr Abstract: 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. Key words: plant extracts; stilbene compounds; stilbene synthase;Vitis vinifera; Botrytis cinerea. Abbreviations: CHS, chalcone synthase; DMRT, Duncan’s multiple range test; FW, fresh weight; PAL, phenyl alanine ammonia-lyase; RT, reverse transcription; STS, stilbene synthase. Introduction Grape (Vitis spp.), which is one of the most com- mon fruits in the world, is exposed to various bacte- rial, fungal, and viral pathogens (Pearson & Goheen 1988), leading to significant reductions in yields (Mon- tesinos 2007). Botrytis cinerea, the causal agent of grey mold, causes significant economic losses during grape production in Korea from bud break to pre- and post- harvest (Jang et al. 1995). However, chemical control of B. cinerea is often difficult due to the appearance of fungicide resistant strains (Kim et al. 1993). Accord- ingly, it is necessary to develop eco-friendly manage- ment systems, such as antifungal compounds derived from natural organisms including bacteria, fungi, and plants during postharvest management of berries (Bel- hadj et al. 2008). Plant phenolics are a large family of compounds showing mostly antioxidant and antimicrobial activity. Some of these compounds, such as stilbenes, are nat- urally occurring in plants as one of self defence-agents (Chung et al. 2003). These compounds have been found in grapevines (Jimenez et al. 2007), pine trees (Kindl 1985), and peanuts (Chung et al. 2003). Until very re- cently, grapevine was the only stilbene-producing plant whose genome had been sequenced. At least 20 different stilbene synthase (STS) genes have been reported to be expressed in grape following infection with Plasmopara viticola (Richter et al. 2005). It is worth mentioning that the phenylalanine ammonia-lyase (PAL) gene fam- ily encoding the first enzyme of the phenyl propanoids pathway has expanded in parallel to the STS gene fam- ily in Vitis spp. Grapevine and wine are important dietary sources of resveratrol to humans (King et al. 2006). The synthesis of resveratrol in grape berries and leaves is known to be stimulated in response to bi- otic and abiotic stresses (Bavaresco & Fregoni 2001). Moreover, stilbene phytoalexins, such as cis- and trans- resveratrol (Langcake & Pryce 1977), trans- and cis- piceid (Waterhouse & Lamuela-Raventos 1994), ptero- stilbene (Pezet & Pont 1988), and piceatannol (Guer- rero et al. 2010; Piotrowska et al. 2012) have been identified in grapes. Cis- and trans-resveratrol, phar- macologically important stilbenes, are present in grape berry skins during all ripening stages, but are almost completely absent from the pulps (Chong et al. 2009). Chalcone synthase (CHS) and STS are key enzymes involved in the biosynthesis of antimicrobial phytoalex- * Corresponding author c 2014 Institute of Molecular Biology, Slovak Academy of Sciences Unauthenticated Download Date | 7/25/18 12:19 AM