Toxic effect of phytotoxin Sirodesmin PL on Brassica napus (colza) seedlings.

ROSSI F.R.; ELLIOT C.; ROMERO F.M.; GARRIZ, A.; RUIZ O.A.

CORDOBA

Congreso; XXXII REUNIÓN ARGENTINA DE FISIOLOGÍA VEGETAL - XVI CONGRESO LATINOAMERICANO DE FISIOLOGÍA VEGETAL; 2018

SAFV

Leptosphaeria maculans is a hemibiotrophic fungus that affect a wide numberof horticultural and agronomic crops such as colza (Brassica napus ssp oleifera).This fungus causes necrosis in leaves and cankers in the stem base andoriginates important economic losses. The pathogen´s virulence depends largelyon the production of secondary metabolites, including the phytotoxin SirodesminPL. This toxin belongs to a wide group of compounds namedepipolythiodioxopiperazine which are characterized by the presence of aninternal disulphide bridge. It has been demonstrated that L. maculans mutants non-producing sirodesmin are less virulent onstems of B. napus.Nevertheless, the toxicity mechanisms of this toxin is far from beingunderstood. Here we demonstrate that Sirodesmin induces necrotic lesions incotyledons at concentrations ranging 5-50 µM,which is in concordance with cell death levels. The ability of Sirodesminto cause cell death was abolished when this compound was maintained in thereduced state by the simultaneous presence of NaBH4. Sirodesmin induces ROS accumulation as evidenced by DCFDAstaining, as well as H2O2 and superoxide accumulation by DABand NBT staining, respectively. Here we demonstrate that this toxin requirefunctional thiols for its toxicity and that it modifies the redox status inplants.