Toxic effect of phytotoxin sirodesmin PL on Brassica napus (canola) seedling

FR ROSSI; ELLIOT CANDANCE; FERNANDO M. ROMERO; ANDRÉS GÁRRIZ; RUIZ OA

Cordoba

Congreso; XXXII Reunion Argentina XVI Congreso Latinoamericano de Fisiología Vegetal 2018; 2018

SAFV

Leptosphaeria maculans is a hemibiotrophic fungusthat affect a wide numberof horticultural and agronomiccropssuchascolza (Brassica napusssp oleifera).This fungus causes necrosis in leaves and cankers inthestembase and originatesimportanteconomiclosses.The pathogen´svirulence dependslargelyon the productionof secondary metabolites, including the phytotoxinSirodesmin PL.Thistoxin belongsto a wide group ofcompoundsnamed epipolythiodioxopiperazine which arecharacterizedby the presence of an internal disulphidebridge. It has been demonstrated that L. maculans mutantsnon-producing sirodesmin are less virulent onstemsof B. napus. Nevertheless, thetoxicitymechanismsof this toxin is far from being understood. Here we demonstratethat Sirodesmin induces necrotic lesions incotyledons at concentrations ranging 5-50 µM, which isin concordance with cell death levels.The abilityof Sirodesmintocausecell death was abolished when thiscompoundwas maintained in the reduced state by thesimultaneous presence of NaBH4. Sirodesmin inducesROS accumulation as evidenced by DCFDA staining, aswell as H2O2 and superoxide accumulation by DAB andNBTstaining, respectively. Here we demonstratethat thistoxin require functional thiols for its toxicity and that itmodifiestheredoxstatusin plants.