COLLETOTRICHUM ACUTATUM PRODUCES A COMPOUND THAT EXERTS OPPOSITE EFFECTS ON THE DEFENSE RESPONSE OF STRAWBERRY PLANTS DEPENDING ON THE PATHOGEN LIFESTYLE

TOMAS GRAU, RH; DIAZ-RICCI, JC

Salta

Congreso; Joint LV Annual SAIB Meeting and XIV PABMB Congress; 2019

The fungal pathogen Colletotrichum acutatum, the causal agent of anthracnose disease causes important economical losses in strawberryfarming worldwide. Crop fungal diseases are usually controlled with fungicides that despite the different origin and chemical nature, arecontaminants of the environment and dangerous for human and animal health. The use of crude or barely purified microbe-derived extractscontaining defense elicitors are interesting alternatives, as they can induce plant defenses with the advantage that they do not require highly135demanding and expensive purification procedures. In this context, we have evaluated the effects on the defense response produced in planta ofthe supernatant obtained from a liquid culture of a virulent isolate (M11) of the hemibiotrophic fungus C. acutatum (M11-CF). Results obtainedshowed that M11-CF is capable to suppress the accumulation of the reactive oxygen species (ROS), and the defense response induced by theprotein AsES against the hemibiotrophic fungus C acutatum. Since M11-CF exhibits the capacity to suppress the oxidative burst, and taking intoaccount that there is a direct correlation between the occurrence of the oxidative burst and the pathogenicity of necrotrophic fungi, wehypothesized that M11-CF may further conferred protection against a necrotrophic pathogen such as B. cinerea. Results indicate that strawberryplants treated with M11-CF induces ethylene accumulation, and up-regulates ethylene-related genes (e.g. FaETR1, FaERS1, FaERF1) causingthe induction of a defense response against B. cinerea. The latter was evidenced by the decrease of the lesion diameter in M11-CF-treated plantsas compared to control plants. In contrast, salicylic acid-related genes (e.g. FaPR1, FaOGBG, FaCHI2-2) did not show changes after thetreatment. This outcome confirms the above mentioned hypothesis about the capacity of M11, and its extracts, to exert opposite effectsdepending on the pathogen tested. That include, to activate a defense response against a necrotrophic pathogen by activating the ethylenepathway, and to suppress a defense response against an hemibiotrophic pathogen by the negative regulation exerted by ethylene on the salicylicacid pathway, and the suppression of the oxidative burst. Results presented here highlights the necessity to make an integral study of themicrobiome present in soils and plant biosphere before applying any bioproduct that would activate the defense response to control crop diseases.