The use of δ¹³C as an indicator of water use efficiency for the selection of drought tolerant grapevine varieties

The wine spoilage caused by Brettanomyces bruxellensis is one of the global concerns for winemakers. Detecting the presence of B. bruxellensis using routine laboratory culture techniques becomes challenging when cells enter the viable but not culturable (VBNC) state. This study aims to investigate the impact of p-coumaric acid (a volatile phenol precursor) and micronutrients on B. bruxellensis’ culturability, viability, and volatile phenol production under sulfite stress. In red wine, exposure to a high sulfite dose (100.00 mg L-1 potassium metabisulfite) resulted in immediate cell death, followed by a recovery of culturability after two weeks.

Rootstocks were the first sustainable and environmentally friendly strategy to cope with a major threat for Vitis vinifera cultivation. In addition to providing Phylloxera resistance, they play an important role in protecting against other soil-borne pests, such as nematodes, and in adapting V. vinifera to limiting abiotic conditions. Today viticulture has to adapt to ongoing climate change whilst simultaneously reducing its environmental impact. In this context, rootstocks are a central element in the development of agro-ecological practices that increase adaptive potential with low external inputs. Despite the apparent diversity of the Vitis genus, only few rootstock varieties are used worldwide and most of them have a very narrow genetic background. This means that there is considerable scope to breed new, improved rootstocks to adapt viticulture for the future.

The fungicidal effect of UV-C radiation (100-280 nm wavelength) is well known, but its applicability for the control of pathogenic molds of grapes is conditioned by its effect on the host and by the risks inherent in its handling[1].
As an alternative, the effect in vitro of UV-B radiation (280-315 nm) on the main pathogenic molds of grapes has been studied: Botrytis cinerea, Aspergillus niger, Penicillium expansum and Rhizopus stolonifer.

Vine growth circumstances are becoming warmer and drier because of climate change. Higher temperatures advance ripening to a point in the season less conducive to the production of fine wine, while drought reduces yields (Van Leeuwen et al., 2019). Several wine-producing regions around the world have already recognized threats to their viticultural viability (Santos et al., 2020). An economical and cost-effective strategy for adaptation is the employment of late-ripening, drought-resistant plant material (varieties, clones, and rootstocks).

Recently, foliar treatments with mineral-based compounds have shown positive effects on grapevine production by protecting grape from thermal excesses and reducing the decoupling between technological and phenolic maturity caused by climate change. Unraveling the effect of mineral particle applications on grape-associated microbes is pivotal for successful wine processing, due to the influence of the microbiota on wine composition and stability. To our knowledge, this is the first work that comprehensively studied the effects of kaolin and chabasite-rich zeolitites treatments on grape-related microorganisms (by real-time PCR quantification of total fungi, Hanseniospora uvarum, Metschnikowia pulcherrima, plant-associated bacteria and lactic acid bacteria), the expression of genes related to the flavonoid biosynthesis (PAL1, CHS1, F3H2, DFR, LDOX, UFGT, MYBA1, GST4, FLS4 genes) and the berry composition (°Brix, pH, acidity and anthocyanin concentrations) in cv. Sangiovese during ripening in two growing seasons (2019 and 2020).