Martinez-Marquez, A.; Martins, V.; Selles-Marchart, S.; Geros, H. V.; Corchete, P.; Bru-Martinez, R.

Stilbenes, particularly trans-resveratrol, play a highly relevant defense role in grapevine as phytoalexin induced in response to stress. Metabolism and transport of stilbenes can be conveniently investigated in grapevine cell culture since large amounts of trans-resveratrol are accumulated in the extracellular medium upon treatment with the elicitor methylated cyclodextrin, either alone or combined with methyl jasmonate. Aiming at finding trans-resveratrol transporter candidates a proteomic approach on grapevine cells membrane fractions was performed. The candidate VvABCB15 was functionally characterized. Its stable expression in both yeast and Silybum marianum cells heterologous systems led to increased trans-resveratrol transport in these hosts. Transient expression in Vitis cells showed an enhanced absorbent- or elicitor-assisted accumulation of extracellular trans-resveratrol in both VvABCB15-expressing or VvGSTU10/VvABCB15-coexpressing cell suspension cultures. Experiments of transient expression in Vitis cell suspensions using light-switchable stilbene synthase (pHYH::VvSTS3) and VvABCB15 further confirmed the role of the candidate as trans-resveratrol transporter. VvABCB15-YFP fusion proteins in Nicotiana leaf showed localization in plasma membrane, being consistent with a functional role in trans-resveratrol transport. This is the first report providing evidence for the involvement of an ABC transporter B-type, VvABCB15 in trans-resveratrol transport to the extracellular medium of grapevine cells.