Culture conditions of Stemphylium lycopersici impacts isolates virulence

MEDINA, ROCIO; FRANCO, MARIO EMILIO ERNESTO; GUSTAVO LUCENTINI; LÓPEZ, SILVINA MARIANELA YANIL; JUAN MANUEL REPARAZ; GAUNA JUAN; SAPARRAT, MARIO CARLOS NAZARENO; BALATTI, PEDRO ALBERTO

Montevideo

Congreso; X ENCUENTRO LATINOAMERICANO Y DEL CARIBE DE BIOTECNOLOGÍA AGROPECUARIA Y XI SIMPOSIO REDBIO ARGENTINA.; 2019

INSTITUTO NACIONAL DE INVESTIGACIÓN AGROPECUARIA - URUGUAY

Stemphylium solani, S. lycopersici and S. botryosum are the causal agents of tomatogrey leaf spot, a disease with high incidence and severity within tomato production areasthat has a relevant economic impact. Necrotrophic fungi of the genus Stemphyliumsynthesize secondary metabolites including host (HSTs) and non-host specific toxins(non-HSTs). The purpose is to study the metabolites synthesized and secreted by S.lycopersici isolate CIDEFI-216 when it is cultured under different conditions and theireffect on plant tissue. CIDEFI-216 was grown on media such as V8, potato dextrose agar(PDA) and potato dextrose broth alone or amended with a filtered macerate of asusceptible tomato hybrid leaves (PDB and PDBs). After 14 days of growth, cultureswere lyophilized, mixed with water, sonicated for 3 hours and like liquid broth culturesfiltered (0.22 um). Leaflets of tomato and leaves of pepper were placed on water-soakedfilter paper in plastic Petri dishes. Then they were wounded with a needle and treatedwith extracts as well as filtered supernatants. Extracts of V8 grown cultures provokedlarger 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 spotonly developed with the supernatant of cultures grown on V8 media. Evidently, CIDEFI-216 synthetize and secrete HSTs and non-HSTs, which is dependent on the cultureconditions as well as the presence of a macerate of leaves.