Culture conditions of Stemphylium lycopersici impacts isolates virulence

MEDINA, ROCIO; FRANCO, MARIO; LUCENTINI, CÉSAR; LOPEZ, SILVINA; REPARAZ, JUAN; GAUNA, JUAN; SAPARRAT, MARIO; BALATTI, PEDRO

Montevideo

Congreso; X Encuentro Latinoamericano y del Caribe de biotecnología agropecuaria y xi simposio REDBIO Argentina.; 2019

REDBIO

Stemphylium solani, S. lycopersici and S. botryosum are the causal agents of tomato grey leafspot, a disease with high incidence and severity within tomato production areas that has arelevant economic impact. Necrotrophic fungi of the genus Stemphylium synthesizesecondary metabolites including host (HSTs) and non-host specific toxins (non-HSTs). Thepurpose is to study the metabolites synthesized and secreted by S. lycopersici isolate CIDEFI216 when it is cultured under different conditions and their effect on plant tissue. CIDEFI-216was grown on media such as V8, potato dextrose agar (PDA) and potato dextrose broth aloneor amended with a filtered macerate of a susceptible tomato hybrid leaves (PDB and PDBs).After 14 days of growth, cultures were lyophilized, mixed with water, sonicated for 3 hours andlike liquid broth cultures filtered (0.22 um). Leaflets of tomato and leaves of pepper wereplaced on water-soaked filter paper in plastic Petri dishes. Then they were wounded with aneedle and treated with extracts as well as filtered supernatants. Extracts of V8 grown culturesprovoked larger lesions on tomato leaflets than those of PDA grown cultures after five days ofincubation. However, the necrotrophic effect was larger when leaflets were treated withextracts from PDB grown cultures. On pepper leaves typical symptoms of grey leaf spot onlydeveloped with the supernatant of cultures grown on V8 media. Evidently, CIDEFI- 216synthetize and secrete HSTs and non-HSTs, which is dependent on the culture conditions aswell as the presence of a macerate of leaves.