ELUCIDATION OF THE PHYSIOLOGICAL ACTIVITY OF LEAF METABOLITES FROM Schinopsis ON Fusarium graminearum, ETHIOLOGICAL AGENT OF CEREAL EAR ROTS

SAMPIETRO, D.A.; ARISTIMUÑO FICOSECO, M.E.; AUDENAERT, K.; VATTUONE, M.A.; CATALAN,C.A.N.

TUCUMAN

Congreso; XXXI ANNUAL SCIENTIFIC MEETING OF TUCUMAN BIOLOGY ASSOCIATION; 2014

TUCUMAN BIOLOGY ASSOCIATION

Schinopsis species from northwest Argentina contain alkylcatechols and terpenoids with inhibitory activity on mycelia growth and spore germination of Fusarium. The action mechanism of these substances could be different or similar to that of commercial fungicides. The aim of this work was to characterize the impact of these metabolites on physiological processes of Fusarium graminearum. Fractions ALK (mix of alkylcatechols), LUPf (lupeol) and M1 (a mix of alkylcatechols and lupeol) were obtained from leaves of Schinopsis lorentzii and S. marginata. The effect of these fractions (250, 125, 62 y 31 μg/ml) was evaluated on suspensions of 106 macroconidia/ml on F. graminearum after 4, 12 and 24 hs. Spore germination and production of H2O2 were evaluated at each time. Production of deoxynivalenol (DON) was determined at the same concentracions after 7 days of fungal growth in trichothecene inducing liquid medium. Prothioconazol was included as positive control. At sublethal dosis, ALK, LUPf and M1 inhibited DON production. With respect to the negative control, ALK and M1 produce a decrease in the release of H2O2 while LUPf had no a significant effect. Prothioconazol, at the sameconcentrations and conditions, increased DON accumulation and H2O2 production. ALK, M1 and prothioconazol did not change the spatial pattern of emergence of the macroconidial germ tubes. The antifungal activity of alkylcatechols and prothioconazol was related to a break in the growth dominance exerted by the end cells in the macroconidia. However, the mentioned phenolic lipids had a different mechanism of antifungal activity because they did not trigger anoxidative burst as prothioconazole did during or before DON production.