EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
EFS12- Book of abstracts - Contact
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SESSION 5: DISEASE CONTROL AND FORECASTING MODELS<br />
P125 - The potential <strong>of</strong> bi<strong>of</strong>ungicides in controlling<br />
soil born pathogen on tomato by inducing defense<br />
response<br />
W. Jendoubi 1 , R. Rodriguez 2 , W. Hamada 1<br />
1 Laboratory <strong>of</strong> Genetics, National Agronomic Institute <strong>of</strong> Tunisia; 2 Sustainable Agro Solutions S.A,<br />
Almacelles (Lleida), Spain<br />
Email: w_hamada@yahoo.com<br />
Some bio-fungicides were characterized for the mode <strong>of</strong> action and their<br />
effectiveness in controlling soil born disease on tomato. Five natural products<br />
containing seaweed, carbohydrates, phosphite, chitosan and the beneficial<br />
bacterium Pseudomonas putida were compared to salicylic acid used as<br />
reference as known to be involved in defense response pathway. Their indirect<br />
mode <strong>of</strong> action was analyzed by application <strong>of</strong> the products on the plants before<br />
challenging with the pathogen. The telluric fungus Fusarium oxysporum f. sp.<br />
radicis Lycopersici (FORL) and the tomato crop were used as model <strong>of</strong> study.<br />
Due to the difficulty <strong>of</strong> monitoring the efficacy <strong>of</strong> products in the amended soil, a<br />
hydroponic system was adopted. After the application <strong>of</strong> either the tested or the<br />
reference products, the effectiveness is evaluated based on the development <strong>of</strong><br />
disease symptoms on shoots and roots <strong>of</strong> the attacked plants. In order to<br />
understand better the mode <strong>of</strong> action <strong>of</strong> these bio-fungicides in planta, analysis <strong>of</strong><br />
the release <strong>of</strong> the secondary metabolites specific <strong>of</strong> plant defense such as soluble<br />
phenolics was undertaken and showed an accumulation <strong>of</strong> these compounds in<br />
leaves <strong>of</strong> treated tomato plants. RT-PCR analysis <strong>of</strong> expression <strong>of</strong> the gene<br />
encoding phenyl-amenia-lyase (PAL), encoding the synthesis <strong>of</strong> phytoalexin<br />
representing parts <strong>of</strong> these compounds, confirmed the results found earlier.<br />
Accordingly, the resistance observed in treated plants may be a direct result to<br />
the accumulation <strong>of</strong> several phenolic compounds. Similarly peroxidase activity<br />
has been assessed in leaves and roots <strong>of</strong> treated and inoculated tomato plants by<br />
FORL. This analysis showed a remarkable increase <strong>of</strong> peroxidase activity in<br />
treated and inoculated plants which is more significant in roots than in leaves. RT-<br />
PCR analysis performed on the gene encoding peroxidase (PR9) confirmed the<br />
results obtained following the peroxidase activity. Molecular analysis was also<br />
undertaken in order to explain the mechanism that may be the basis <strong>of</strong> the type <strong>of</strong><br />
reaction observed. This analysis was based on monitoring the expression <strong>of</strong> three<br />
genes encoding for three PR proteins namely PR2, PR4 and PR1and a gene that<br />
lies upstream <strong>of</strong> all proteins PRs (NPR1). Follow up <strong>of</strong> the gene expression<br />
showed accumulation <strong>of</strong> the PR proteins depending on the applied product. Thus,<br />
we can conclude that part <strong>of</strong> the resistance observed may be explained by the<br />
accumulation <strong>of</strong> transcripts <strong>of</strong> PR4, PR2 and PR1 after products application.<br />
Keywords: bi<strong>of</strong>ungicides, plant defense activator, Fusarium<br />
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