Unveiling the Shield: Decoding UPSIDE®-Induced Biochemical Responses Against Botrytis cinerea in Grapevine

Giulia Scimone¹Lorenzo Mariotti¹Zuzana Gelová²Lisa Milanollo²Claudia Pisuttu^1*Elisa Pellegrini¹Cristina Nali¹

• ¹Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy
• ²Kwizda Agro GmbH, Vienna, Austria

This study aims to investigate biochemical changes on grapevine induced by the application of UPSIDE® (U), a new yeast-based product developed for organic viticulture. Foliar spray applications of U were carried out once a week for three consecutive weeks on potted grapevines (U+), while other plants were sprayed with sterile water (U-). At the end of the treatments, half plants from each group were Botrytis cinerea (Bc+)- or mock-inoculated (Bc-). Fully expanded leaves were sampled at 24 hours after each spray, and at 1-, 3-, 24-and 48-hours post inoculation (hpi), and then used for biochemical analysis and microscopic observations. In U+/Bc-plants, hydrogen peroxide levels increased at all analysis times (+50% on average), along with a 3-fold rise in ethylene/jasmonic acid (Et/JA) ratio at 3 hpi, in comparison to U-/Bc-. In U-/Bc+ plants, the Et/JA ratio remained high throughout the experiment, peaking at 48 hpi, while salicylic acid (SA) dropped at 1 hpi (more than 7-fold and –42%, respectively, compared to U-/Bc-ones). Similarly, U+/Bc+ plants showed increased levels of Et/JA ratio from 3 to 48 hpi and abscisic acid at 3 hpi (5-and 16-fold, respectively, compared to U-/Bc-), with a SA decrease at 1 hpi (–63%, in comparison to U-/Bc-). Microscopic observations revealed fully hyphal spread on U-/Bc+ leaves, while U+/Bc+ showed only slightly formed and misshaped germ tubes. Results confirmed the potential of U in triggering plant defense responses, thus protecting grapevine leaves against Bc.