Stilbene production in response to methyl jasmonate and light in cell cultures of several Vitis species

Stilbenes are secondary metabolites produced by grapevine in response to stress, which play the role of phytoalexins in the plant (1). Recently, stilbenes have received a great deal of attention both for their biological role in the plant and for their well-proven biological activities on human health (1). Plant cell cultures have been investigated for their potential as valuable system for stilbene production (2). Among different elicitors, methyl jasmonate (MeJa) was shown to be the most effective in stimulating stilbene biosynthesis in cell suspension cultures of cultivar Italia (2). In the plant, the accumulation of stilbenes is induced by the presence of phytopathogenic fungi (3) or by abiotic stimuli as UV radiation (4). Different stilbenes produced by grapevine show a synergistic activity, furthermore the quali-quantitative composition of stilbene content determines the resistance against specific pathogens. The species Vitis vinifera includes several cultivars quite different from the genetic point of view, since they are exclusively agamic propagated. Consequently, each of these shows different levels of susceptibility to pathogens, such as Botrytis cinerea, Aspergillus spp. and Plasmopara viticola in relation to the different stilbene profile. Recently, great interest has been also addressed for species of Vitis popularly known as “american grapes”, introduced in Europe as rootstocks due to their resistance against some important pathogens of V. vinifera . At present, resistance mechanisms of the american grapes are still unknown. The few avaiable data has been obtained from samples cultivated in field, where the conditions are not fully under control. Our study is focused on the biosynthesis of stilbenes, firstly resveratrol (the main exponent) and viniferins (resveratrol oligomers), in response to biotic stress in cell cultures of several Vitis species. Stilbene content was compared in cell extracts obtained from Vitis spp. cell lines subjected to elicitation with MeJa, grown under continuous darkness or 16/8 h (light/dark) photoperiod. The main stilbenes involved in resistance against phytopathogenic fungi were identified and quantified by means of HPLC. Unexpectedly, the obtained results indicate that cultivars of V. vinifera have a higher stilbene content than the american grapes. For instance, V. vinifera cv. Malvasia, in response to MeJa, increases the production of total stilbenes from 2.58 to 15.58 mg/g DW while Vitis rupestris cv. du Lot increases from 2.80 to 8.97 mg/g DW. Moreover, cell lines grown under photoperiod accumulate higher levels of total stilbenes, both constitutively and in response to elicitation (e.g. Malvasia: from 8.69 to 37.81 mg/g DW).