Grapevine downy mildew, caused by the biotrophic oomycetePlasmopara viticola, is one of the most important diseases in modern viticulture. The search for sustainable disease control measure is of extreme importance, thus becoming imperative to fully characterize the mechanisms leading to an incompatible interaction. We have previously shown that lipid signalling events play an important role in grapevine’s response to this pathogen, namely through changes in linolenic acid content, lipid peroxidation and jasmonic acid synthesis. Here, we have characterized the modulation of lipid metabolism in leaves from twoV. viniferacultivars (resistant and susceptible toP. viticola) in the first hours after pathogen inoculation. Prior to pathogen inoculation both genotypes present an inherently different fatty acid composition that is highly modulated in the resistant genotype after pathogen challenge. Such changes involve modulation of phospholipase A activity suggesting that the source of lipids mobilized upon pathogen infection are the chloroplast membranes. This work thus provides original evidence on the involvement of lipid signalling and phospholipases in grapevine immune responses to pathogen infection. The results are discussed considering the implications on the plant’s physiological status and the use of discriminating lipid/fatty acids pattern in future selection procedures of cultivars.

Grapevine downy mildew, caused by the biotrophic oomycete Plasmopara viticola, is one of the most severe and devastating diseases in viticulture. Unravelling the grapevine defence mechanisms is crucial to develop sustainable disease control measures. Here we provide new insights concerning fatty acid’s (FA) desaturation, a fundamental process in lipid remodelling and signalling. Previously, we have provided evidence that lipid signalling is essential in the establishment of the incompatible interaction between grapevine and Plasmopara viticola. In the first hours after pathogen challenge, jasmonic acid (JA) accumulation, activation of its biosynthetic pathway and an accumulation of its precursor, the polyunsaturated α-linolenic acid (C18:3), were observed in the leaves of the tolerant genotype, Regent. This work was aimed at a better comprehension of the desaturation processes occurring after inoculation. We characterised, for the first time in Vitis vinifera, the gene family of the FA desaturases and evaluated their involvement in Regent response to Plasmopara viticola. Upon pathogen challenge, an up-regulation of the expression of plastidial FA desaturases genes was observed, resulting in a higher content of polyunsaturated fatty acids (PUFAs) of chloroplast lipids. This study highlights FA desaturases as key players in membrane remodelling and signalling in grapevine defence towards biotrophic pathogens.

The domesticated species Vitis vinifera L. harbours many cultivars throughout the world that present distinctive phenology and grape quality. Not only have the grapes been used for human consumption, but the leaves are also used as a source of bioactive compounds and are present in the diets of several Mediterranean countries. We have selected seven different cultivars and performed elemental, fatty acid (FA) and pigment profiling. Total reflection X-ray fluorescence (TXRF) enabled the identification of 21 elements. Among them, Na, Ca and K were highly represented in all the cultivars and Zn was prevalent in V. vinifera cv. ‘Pinot noir’ and ‘Cabernet sauvignon’. Through gas chromatography, six FAs were identified, including omega-3 and omega-6 FA, the most abundant mainly in V. vinifera cv. ‘Tinta barroca’, ‘Pinot noir’ and ‘Cabernet sauvignon’. FA composition was used to determine nutritional quality parameters, namely atherogenic, thrombogenic, hypocholesterolemic/hypercholesterolemic and peroxidisability indexes as well as oxidability and oxidative susceptibility. Grapevine leaves were highlighted as a suitable source of health-promoting lipids. Given the popularity of “green” diets, we have also performed a leaf pigment analysis. Seventeen pigments including chlorophylls, trans-lutein, b-carotene and zeaxanthins were detected. ‘C19’ presented the highest content of most of the detected pigments.