Métodos para preservação de Colletotrichum lindemuthianum e Pseudocercospora griseola

Abstract

Microorganisms are used in laboratories around the world and are essential for many research programs. An effective form of conserving microorganisms of economic interest is the preservation in collections. The maintenance and preservation of these cultures must maintain their original characteristics, purity and stability. Many methods are used and described in literature, however, none are efficient and recommended for all fungi. The objective of this work was to evaluate the different short term preservation methods, considering the maintenance of the original characteristics of the C. lindemuthianum and P. griseola. We used nine isolates, being six of them C. lindemuthianum and three of them P. griseola, which were maintained in the following storage methods during 180 days: Castellani, paper strips, silica gel, freezing using 5% and 10% glycerol, with mycelium and spore suspension. We conducted two experiments in a completely randomized design in a subdivide plots and factorial scheme. The following characteristics were evaluated: sporulation rate, germination percentage, mycelia growth index (MGI), colony diameter (CD) and pathogenicity. These characteristics are important to test the efficiency of each storage method. The data obtained were submitted to analysis of variance and the means were compared to the means obtained before the storage by means of the t Student test at 5% of significance. The results obtained showed that the Castellani and paper strips methods are more efficient for the short term storage and maintenance of C. lindemuthianum isolates. However, the cryopreservation methods for mycelium in glycerol in the concentrations of 5% and 10% preserved the evaluated pathogen characteristics, being that the pathogenicity of the C. lindemuthianum isolates was not affected by the different storage methods. All methods showed efficiency in maintaining the P. griseola isolates.