Vitis rotundifolia Skin Extract

Breeding for varieties carrying natural resistance (R) against plant-parasitic nematodes is a promising alternative to nematicide ban. In perennial crops, the long plant−nematode interaction increases the risk for R breaking and R durability is a real challenge. In grapevine, the nematode Xiphinema index has a high economic impact by transmitting Grapevine fanleaf virus (GFLV) and, to delay GFLV transmission, rootstocks resistant to this vector are being selected, using Muscadinia rotundifolia in particular as an R source. To optimize in fine this strategy, the durability has been studied under controlled conditions in F1 and BC1 muscadine-derived resistant accessions previously obtained from either hardwood-cutting or in vitro propagation. After inoculation with a mix, in equal proportions, of four lines representative of the X. index diversity, multiplication on plants has been monitored 3 to 6 years. The nematode reproduction factor remained lower than 1 in resistant plants obtained from hardwood cuttings while it increased at values far beyond 1 in resistant plants of in vitro origin. Data for nematode numbers per gram of roots mostly paralleled those obtained for the reproduction factor. The effect of the propagation type on resistance over years was also evaluated for the ratio female/juvenile and the frequency of males. Altogether our results illustrate that the muscadine-derived resistance based on hardwood cuttings is durable. By contrast, in resistant and reference accessions obtained from in vitro, our data suggest that the increased nematode multiplication might be mainly due to the modification of root architecture consecutive to this propagation method.

This study evaluated the total phenolic content, phenolic composition, antioxidant and in vitro antiproliferative properties of seeds and skins of 31 different grape cultivars. These properties of seeds and skins varied greatly among grape cultivars. European grapes had the highest values of phenolic compounds, antioxidant properties in seeds followed by Muscadine > American grapes > Oriental grapes. European grape seed extracts also were the strongest in inhibiting the growth of HepG2 cell, followed by American grapes > Muscadine > Oriental grapes. While these values of the Euro-Asian or Euro-American hybrids fell between the parents. However, the differences of these values in skin extracts among different grape cultivars were not significant. The antiproliferative activities were significantly correlated to the three antioxidant assays and the main phenolic compounds. PRACTICAL APPLICATIONS: This study presents phenolic compounds, antioxidant, and in vitro antiproliferative properties of seeds and skins of 31 different grape cultivars. The information is highly relevant to the ever-increasing need for natural sources of antioxidants or nutraceuticals among consumers. The study also provides information for grape geneticists to breed cultivars with higher nutritional value, and for food scientists to exploit the natural polyphenol antioxidants in various grape pomace.