A novel NADPH-dependent aldehyde reductase gene fromVigna radiataconfers resistance to the grapevine fungal toxin eutypine.

Summary:Eutypine, 4-hydroxy-3-(3-methyl-3-butene-1-ynyl) benzyl aldehyde, is a toxin produced byEutypa lata,the causal agent of eutypa dieback of grapevines. It has previously been demonstrated that tolerance of some cultivars to this disease was correlated with their capacity to convert eutypine to the corresponding alcohol, eutypinol, which lacks phytotoxicity. We have thus purified to homogeneity a protein fromVigna radiatathat exhibited eutypine-reducing activity and have isolated the corresponding cDNA. This encodes an NADPH-dependent reductase of 36 kDa that we have namedVigna radiataeutypine-reducing enzyme (VR-ERE), based on the capacity of a recombinant form of the protein to reduce eutypine into eutypinol. The strongest homologies (86.8%) of VR-ERE at the amino acid level were found with CPRD14, a drought-inducible gene of unknown function, isolated fromVigna unguiculataand with an aromatic alcohol dehydrogenase (71.7%) fromEucalyptus gunnii. Biochemical characterization of VR-ERE revealed that a variety of compounds containing an aldehyde group can act as substrates. However, the highest affinity was observed with 3-substituted benzaldehydes. Expression of aVR-EREtransgene inVitis viniferacells culturedin vitroconferred resistance to the toxin. This discovery opens up new biotechnological approaches for the generation of grapevines resistant to eutypa dieback.. [ABSTRACT FROM AUTHOR]