DNA-free editing to improve stress resilience of wine grape genotypes recalcitrant-to-regeneration

The pinking of in white wine is the turning of color from yellow to salmon hue. White wines obtained from certain grape varieties (e.g. Chardonnay, Sauvignon blanc, Riesling, Trebbiano di Lugana) showed to be susceptible to pinking [1] that has been evaluated by an assay providing the addition of hydrogen peroxide. Even if its appearance does not seem to affect the sensory properties [2], strategies are necessary for its removal. Nowadays, the treatment with polyvinylpolipirroline (PVPP) was reported to significantly decrease the pink color [3].

Carbaryl is an acetylcholine esterase inhibitor-type insecticide used for pest control on grapevine. We repeatedly observed the occurrence of interveinal leaf necrosis following carbaryl spray application in a Vitis rupestris x Vitis riparia F1 hybrid progeny vineyard. Spray applications induced necrosis in this progeny under both Missouri and New York field conditions an approximate one-to-one sensitive-to-insensitive segregation ratio and with 42% concordance. Results of subsequent in vitro experiments established causality between carbaryl treatment and leaf necrosis and confirmed the pattern of segregation observed in the field. We consistently map this phenotype to a major QTL on chromosome 16 of the female parent V. rupestris ‘B38’ regardless of whether we used field or in vitro-generated phenotype data.

Temperature is a key environmental factor affecting grape primary and secondary metabolites. Even if several mesoscale studies have already been conducted on temperature
especially within a Protected Designation of Origin area, few data are available at an intra-block scale. The present study aimed at i) assessing the variability in bunch zone air temperature within a single vineyard block and the temporal stability of temperature spatial patterns, ii) understanding temperature drivers and
iii) identifying the impact of temperature on grape berry attributes.

Traditionally, non-saccharomyces yeasts were deemed undesirable in winemaking, for this reason, it is a common practice to add sulphites to prevent their proliferation during the initial stages of vinification. However, the current research on yeast diversity has unveiled numerous non-saccharomyces strains possessing advantageous traits that enrich the sensory profile of wines. The genus hanseniaspora is often associated with wine fermentation and is also commonly found on grapes.

Using viticultural and enological techniques to increase aromatics in white wine is a prized yet challenging technique for commercial wine producers. Equally difficult are challenges encountered in hastening phenolic maturity and thereby increasing color intensity in red wines. The ability to alter organoleptic and visual properties of wines plays a decisive role in vintages in which grapes are not able to reach full maturity, which is seen increasingly more often as a result of climate change. A new, yeast-based product on the viticultural market may give the opportunity to increase sensory properties of finished wines. Manufacturer packaging claims these yeast derivatives intensify wine aromas of white grape varieties, as well as improve phenolic ripeness of red varieties, but the effects of this application have been little researched until now. The current study applied the yeast derivative, according to the manufacture’s instructions, to the leaves of both neutral and aromatic white wine varieties, as well as on structured red wine varieties. Chemical parameters and volatile aromatics were analyzed in grape musts and finished wines, and all wines were subjected to sensory analysis by a tasting panel. Collective results of all analyses showed that the application of the yeast derivative in the vineyard showed no effect across all varieties examined, and did not intensify white wine aromatics, nor improve phenolic ripeness and color intensity in red wine.