The Effect of Copper Toxicity on Two Vitis vinifera Varieties Resistant to Plasmopara viticola Infection - ISRR 2018 10th Symposium for the International Society of Root Research

Silvia Celletti ¹ Stefano Rizzi ^1,2,3 Stefano Nadalini Stefano Nadalini ^1,2,3 Youry Pii ¹ Youry Pii Fabio Valentinuzzi ¹ Tanja Mimmo ¹ Roberto Terzano ⁴ Ignazio Allegretta ⁴ Guido Cipriani ² Oscar Giovannini ³ Ilaria Pertot ^3,5 Stefano Cesco ¹

¹Faculty of Science and Technology, Free University of Bozen-Bolzano, I-39100 Bolzano, Italy
²Dipartimento di Scienze Agroalimentari, Ambientali e Animali, University of Udine, Via delle Scienze 206, 33100, Udine, Italy
³Research and Innovation Centre, Fondazione Edmund Mach (FEM), Via E. Mach 1, 38038, San Michele all'Adige, Italy
⁴Department of Soil, Plant and Food Sciences, University of Bari, Via Amendola 165/A, 70126, Bari, Italy
⁵Center Agriculture Food Environment (C3A), University of Trento, via E. Mach 1, 38038, San Michele all’Adige, Italy

Plasmopara viticola is one of the most relevant pathogen causing severe grapevine production losses worldwide (downy mildew). A wide number of antifungal compounds has been developed in order to protect plants from phytopathogens. Copper (Cu)-based fungicides are commonly used as fungicides against downy mildew. Over time, the high and regular application rate led to an over-accumulation of Cu in the upper soil layers of vineyards, inducing negative effects not only on plants, but also on all organisms living there. The resistant grapevine cultivars need a limited number of fungicide treatments per year and could represent a possible solution to overcome further Cu accumulations in soil and related toxicity.

The aim of the present study is to investigate if soil Cu contamination could interfere with the response of two resistant grapevine varieties (i.e. Sauvignon Kretos and Cabernet Volos) against P. viticola. In particular, both cultivars possess the resistant gene Rpv 12, introgressed in their genome. These two resistant cultivars were exposed to different soil Cu levels, artificially inoculated with the pathogen, and evaluated in terms of resistance to the pathogen and intensity of the disease. In addition, physiological parameters were also assessed.

This work demonstrated that Cu toxicity does not impair the full expression of the resistance against P. viticola in the two tested cultivars. Moreover, although no visual Cu stress symptoms on plants were noticed, the assessment of biomass production, release of root exudates, bioavailability and nutrient uptake revealed that both varieties were responding to Cu stress yet being Cabernet Volos more efficient in tolerating soil Cu contamination than Sauvignon Kretos. Further experiments, involving higher soil Cu levels and a longer inoculum period, could further unravel the mechanisms adopted by the two resistant cultivars in more severe Cu pollution conditions.

Research funded by the Free University of Bolzano (TN2053).