Malate content in wild vitis spp. Demonstrates a range of behaviors during berry maturation

Wild Vitis spp. and their interspecific hybrids are known to have high malate concentrations at sugar maturity as compared to domesticated Vitis vinifera, but it is unknown if differences in malate at harvest among species arise from differences in malate accumulation or degradation. Over two years, fruit from Vitis riparia and Vitis cinerea accessions along with commercial V. vinifera and interspecific hybrid cultivars were collected at multiple time points. In contrast to the well-known biphasic behavior of malate in V. vinifera (preveraison accumulation, postveraison degradation), we observed a range of behaviors for malate in wild species. On average, V. riparia accessions had malate per berry comparable to V. vinifera just prior to veraison, but degraded malate to a much lesser extent. V. cinerea accessions had lower malate prior to veraison than other species but showed an increase in malate from pre-to postveraison. Variation in postveraison malate behavior appears related to diminished malate degradation in the mesocarp of wild Vitis spp. Our results indicate that studies of malate behavior in Vitis spp. and their hybrids should include both pre-and postveraison time points.