Induction of polyphenols in seedlings of Vitis vinifera cv. Monastrell by the application of elicitors

Contamination problems arising from the use of pesticides in viticulture have raised concerns. One of the alternatives to reduce contamination is the use of elicitors, molecules capable of stimulating the natural defences of plants, promoting the production of phenolic compounds (PC) that offer protection against biotic and abiotic stress. Previous studies on Cabernet-Sauvignon seedlings demonstrated that foliar application of elicitors methyl jasmonate (MeJ) and benzothiadiazole (BTH) increased proteins and PC involved in grapevine defence mechanisms. However, no trials had been conducted on Monastrell seedlings, a major winegrape variety in Spain. To address this gap, a trial was conducted to assess whether MeJ and BTH application could enhance the biosynthesis of PC involved in the defense mechanisms of Monastrell seedlings. The trial involved grapevine seedlings of the Monastrell variety grown in individual pots in a controlled environment. Four treatments were administered, including water (control), MeJ, BTH, and a combination of MeJ and BTH. Leaf samples were collected at various time intervals, and the quantification of stilbenes and flavonols was carried out. The results demonstrated that the elicitor treatments positively influenced the biosynthesis of stilbenes and flavonols. The application of MeJ led to significant increases in the production of key grapevine antimicrobial stilbenes, as well as some flavonols, particularly at 18-hours after treatment. These increases remained above control levels throughout the trial. The effects of BTH and MeJ+BTH treatments were less pronounced compared to MeJ alone, with the highest increase observed at 24-hours after treatment. However, they were always greater than the control. Overall, the findings suggest that the application of MeJ and BTH has the potential to improve the defence mechanisms of Monastrell vines, reducing reliance on chemical treatments. Further research is needed to validate the elicitor activity of MeJ and BTH against common grapevine diseases.