Potencial patogênico e recuperação da esporulação de isolados de Pestalotiopsis microspora do eucalipto após longo período de armazenamento

Abstract

The eucalyptus crops can be attacked by several pathogens, mainly fungi, among which, Pestalotiopsis sp. it is known as easily spread fungi, infecting diverse botanical hosts. For their diagnosis and study of their in vitro behavior, often, its isolation is required. However, many plant pathogens isolates, after long periods of storage or successive cuttings lose their pathogenic potential or sporulation capacity, needing the use of recovery techniques, in order to preserve the viability of the microorganism as long as possible. The objective of this study was to evaluate the pathogenic potential and methodologies for recovery of the sporulation of P. microspora isolates that lost its sporulation capacity after subjected to a long storage period. Isolates of P. microspora were kept for a long storage period (14 months) in Petri dish at 10°C. After this period, the isolates colonies showed reduced mycelial growth and none sporulation. The isolates were inoculated on healthy eucalyptus leaves and after ten days, they were subjected to three reisolation methods: scraping of the lesions (S) removing of injured plant tissue fragments, followed by disinfestation (D) and without disinfestation (WD), aiming to evaluate the method that provide better fungal colonies growth. Just after, the purified isolates were evaluated for the recovery of its sporulation ability. After the experiments it was found in the pathogenicity assay that the isolated E-72-02 was higher than the others as the area under the disease progress curve (AUDPC); in reisolation, the methodology without disinfestation (WD) was higher than the others (S and D) as to P. microspora mycelium growth. When evaluating the individual sporulation average, when subjected to the three recovery methods, it was found that all isolates recovered the ability to sporulate, on wath the isolate E-72-03 was higher to the others. At the end of the use of different methods for reisolation, the occurrence of differences among the isolates showed that sporulation is a isolated-dependent feature. The three methods (S, WD and D) allow the sporulation rocovery of P. microspora after these isolates have been subjected to long storage period.