A novel NADPH-dependent aldehyde reductase gene from Vigna radiata confersresistance to the grapevine fungal toxin eutypine

Eutypine, 4-hydroxy-3-(3-methyl-3-butene-1-ynyl) benzyl aldehyde, is a toxi n produced by Eutypa lata, the causal agent of eutypa dieback of grapevines . It has previously been demonstrated that tolerance of some cultivars to t his disease was correlated with their capacity to convert eutypine to the c orresponding alcohol, eutypinol, which lacks phytotoxicity. We have thus pu rified to homogeneity a protein from Vigna radiata that exhibited eutypine- reducing activity and have isolated the corresponding cDNA. This encodes an NADPH-dependent reductase of 36kDa that we have named Vigna radiata eutypi ne-reducing enzyme (VR-ERE), based on the capacity of a recombinant form of the protein to reduce eutypine into eutypinol. The strongest homologies (8 6.8%) of VR-ERE at the amino acid level were found with CPRD14 a drought-in ducible gene of unknown function, isolated from Vigna unguiculata and with an aromatic alcohol dehydrogenase (71.7%) from Eucalyptus gunnii. Biochemic al characterization of VR-ERE revealed that a variety of compounds containi ng an aldehyde group can act as substrates. However, the highest affinity w as observed with 3-substituted benzaldehydes. Expression of a VR-ERE transg ene in Vitis vinifera cells cultured in vitro conferred resistance to the t oxin. This discovery opens up new biotechnological approaches for the gener ation of grapevines resistant to eutypa dieback.