Universidad Nacional de Tucumán - Facultad de Bioquímica, Química y Farmacia
August 11, 2014 | 4 ′ 1 ′′
Teachers advance in the use of yeasts capable of reducing the incidence of fruit mildew and stalk rot, fungal diseases which affect lemons after harvest. The researchers isolate yeasts of citrics of plants in Tucumán to use them as biocontrollers and avoid the use of fungicides.
Argentina is the main world exporter of lemons and Tucumán contributes 84% of the total cultivated in a surface of 34,000 hectares, according to the data from the Instituto Nacional de Tecnología Agropecuaria (INTA). Taking into account this reality, a group of researchers from the Facultad de Bioquímica, Química y Farmacia of the Universidad Nacional de Tucumán, who also work in the Planta Piloto de Procesos Industriales Microbiológicos (PROIMI) (Pilot Plant of Microbiological Industrial Processes), developed a working line oriented to find alternatives for the biological control of lemons after harvest.
The topic studied by the biochemists and doctors in Biological Sciences Julián Dib and Verónica Fernández Zenoff with the collaboration of Luciana Contreras, student of the BS in Biotechnology and the biochemist Lydia Garnica, is a new alternative to treat lemons with fungal diseases.
The researchers said to Argentina Investiga that the most common post-harvest diseases which affect citrics are green mildew and blue mildew, caused by Penicillium digitatum and P. italicum, respectively, which get in the fruit through the wounds in the surface. To a lesser extent, citrics are affected by Phomopsis citri, which causes stalk rot.
Contreras said that the work consisted in isolating yeasts from citrics (lemons, oranges, grapefruit and tangerines) of plants in Tucumán which were not treated with fungicides and which could be avoided by the use of these biocontrollers. “In the first stage in vitro tests were carried out in the laboratory in dishes where the yeasts called “killer” were faced with the pathogenic fungi and we got satisfactory results”, said the young researcher. These yeasts are called “killer” because they are capable of killing fungi or pathogenic organisms present in the fruit. She added that in vivo tests were made later. “We inoculated the fruit with the best result yeast in the in vitro stage and with the pathogenic agent to observe the results”, she detailed.
This biological alternative to fight lemon diseases can be fundamental for Tucumán’s producers, as in some countries of the European Union there are phytosanitary barriers for the fruit submitted to treatment with fungicides which could be avoided with the use of these biocontrollers.
Julián Dib explained that one of the main problems after harvest is the loss produced by fungal diseases and that motivated the working team to deal with this area. “Nowadays, there are alternatives to solve this problem through chemical substances like fungicides, but which can have residual effects and cause negative effects on the population. We generate an alternative which is organic production”, he stated.
Dib explained that yeasts are noble organisms which were used for thousands of years to produce wine, beer and bread. “What is good about these yeasts is that they are isolated from the citric plants in Tucumán, we do not bring foreign microorganisms, which is an advantage. Of 400 isolated yeasts, just 15% has showed antagonistic activity from that of these fungi”, described the professional.
“In addition to testing the killer effect of yeasts against pathogenic agents, we classified in parallel yeasts with molecular biology techniques, extract their DNA and amplify a DNA region to investigate”, concluded the thesis work’s co-director.
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