"Stemphylium lycopersici isolates secrete phytotoxic compounds as a result of their interaction with tomato plant extracts

BARTEL, LAURA C.; MEDINA, ROCIO; LUCENTINI, CÉSAR G.; SAPARRAT, MARIO C. N.; BALATTI, PEDRO A.

Pittsburgh

Congreso; Plant Health 2022; 2022

The American Phytopathological Society (APS)

Tomato (Solanum lycopersicum L.), a common worldwide cultivated vegetable, isaffected by many pathogens. In Argentina is relevant the Tomato grey leaf spot, afungal disease caused by Stemphylium lycopersici. Previously, we found that isolates ofS. lycopersici differ in growth, sporulation and aggressiveness as well as in their profileof volatile and soluble secreted compounds. We hypothesized that the presence of plantsubstances modifies the synthesis of soluble secreted compounds by S. lycopersiciassociated with virulence. The isolates CIDEFI 213 and CIDEFI 216 were used, whichdiffer in virulence capacity. Supplemented CZAPEK was made by the addition ofextract of leaves of 45-days-old tomato plants cv. TL 42,524 (Syngenta) in CZAPEKmedia. Isolates were grown on CZAPEK and supplemented CZAPEK media (14days). The supernatants were recovered and soluble compounds were extracted,evaporated and re-dissolved in methanol HPLC-grade. The compounds profiles were analysed by HPLC/DAD and phytotoxicity of the fungal extracts was evaluated. TheUV profiles of the isolates were similar in both culture conditions sharing several peaks.One peak was qualitatively higher (5X) when CIDEFI 216 grown in supplementedmedia, while others changed slightly. Phytotoxicity tests showed higher necrosis whenCIDEFI 216 extracts from supplemented media was used. On the contrary, nodifferences were observed for CIDEFI 213 neither between UV profiles nor toxicitytests. These results suggest that plant substances modify the synthesis of S. lycopersicimetabolites related with its virulence.