Unravelling the Biochemical and Molecular Priming Effect of a New Yeast-Derived Product: New Perspectives towards Disease Management

Plants constantly face the environment that surrounds them and fight for survival against biotic and abiotic stress factors. To deal with harmful conditions, plants have developed a multilayer defence system, making them capable of recognising threats and promptly recovering from them. This phenomenon, which takes advantage of the "memory effect", is referred to as bio-priming and represents a new frontier in terms of crop protection. Here, we investigated the "indirect" protective mechanisms of a new yeast extract formulate in Vitis vinifera cv. Sangiovese plants at both the biochemical and genic levels. The formulate was applied once a week for three consecutive weeks, and grapevine leaves were sampled from the first to the fifth day after treatment (dat) at every week of the experiment. Increased levels of jasmonic acid (every week at 2 dat; +70% as average) and abscisic acid (at 1 dat of the first week, more than 1.7-fold higher than the control) and the underproduction of salicylic acid (from 2 dat; -18%) confirmed that these signalling molecules/"specialised compounds" are actively involved in the early activation of defence pathways in treated vines. In addition, pr2 and chit1b, two genes involved in regulating hormonal crosstalk, were significantly up-regulated (both in the first and second week of the trial) and were also found to underlie upstream molecular activation. The results obtained by this investigation confirm the use of this new product to prime and protect grapevines from a wide range of fungal and fungal-like plant pathogens through the induction of defence responses.