ABSTRACT
The present study was conducted to compare different laboratory preservation methods and to realize physiological characterization of Verticillium sp. For the viability tests, samples of V. dahliae from eggplants, tomato, peanuts, okra plants and Solanum gilo, as well as V. albo-atrum from potato plants preserved by periodic transfers, Castellani’s method or distilled water, liophylization and mineral oil were transferred to culture media PDA and AA. Only 4 isolates had samples preserved by liophylization, and only 1 isolate had samples in mineral oil (OM). Upon culture growth, experimental inoculations in soil were conducted for the tests of pathogenicity in the original host. For the morphologic characterization, the cultures were cultured in Czapeck culture medium and for physiological characterization the cultures were inoculated in the various hosts from which they had been isolated. The results showed that Castellani’s method is the most efficient to preserve this fungus genus, because the plants inoculated with samples preserved by this method presented symptoms more quickly and the pathogen was more aggressive. In Czapeck, IB02/01 and IB247 presented the greatest amount of microslerotia, as the entire back of the plate presented black coloration. The cultures IB669, IB829 and IB752 had white and delicate mycelium with a little formation of microesclerotia. Isolate IB7/75 presented a mycelium without microeslerotia. The crossed inoculations showed that okra plants were more susceptible, while the peanut, tomato and eggplant were less susceptible, only infected by the original isolate. Isolate IB7/75 (V. albo-atrum), was able to cause infection in potato plants (original host) and also infected cucumber plants, used for the differentiation of species V. dahliae and V. albo-atrum, proving the correct identification of this culture.
KEY WORDS
Laboratory preservation; fungi; viability; pathogenicity and cross inoculations
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