EFFICIENCY OF NATURAL PRODUCTS IN THE CONTROL OF COLLETOTRICHUM ACUTATUM MONITORED BY REAL-TIME PCR

Strawberry anthracnose, caused by Colletotrichum acutatum J.H. Simmonds, has been reported from most areas of the world where strawberries are grown. The use of chemical phytosanitary products to control fungal diseases has been drastically reduced by EU legislation. For that reason, the development of non-chemical alternatives respectful with the environment and human health is urgent. This study tries to evaluate the effect of two natural products which previously showed a potential as plant defense inductors and in vitro biofungicide activity in the control of C. acutatum. Strawberry plants grown under temperature and humidity controlled conditions were treated with a biofungicide product containing seaweed (Ascophyllum nodosum) and cinnamon (Cinnamomum sp.) extracts (0.5%); a plant defense inductor based on quitosan (0.25%); a chemical fungicide (0.3% Chlorthalonil) as positive control, and water as negative control. 24 h after application of these products, plants were inoculated with a conidial suspension of C. acutatum. Non-treated and non-inoculated plants were used as control of natural occurring infection. The progress of C. acutatum infection was monitored by quantifying the amount of fungi at 24 h, 72 h, 7 days and 15 days after inoculation. A reliable, sensitive and fast TaqMan real-time PCR using dilutions of plant crude extracts, without the need of DNA extraction, was used to detect and quantify C. acutatum in the treated and then inoculated plants. Results demonstrated the efficiency of the assayed natural products in controlling the development of the fungus in the plant up to 15 days after treatment. This real-time PCR method based in the use of plant crude extract allows a rapid and sensitive detection and quantification of low amounts of fungus in the plant, even before the appearance of symptoms.