engleski

Hypovirus CHV 1 in Croatia – basis for biological control of chestnut blight

The chestnuts blights fungus, Cryphonectria parasitica(Murr.) Barr., is mainly responsible for the decline of the European chestnut (Castanea sativa Mill.) in Croatia. However , C. parasitica is a host for naturally occuring hypovirus which causes a reduction in fungal virulence and its reproductive capacties, enabling a biological control of the fungal pathogen. Since recovery of the chestnut forests is dependent on the natural occurence of the hypovirulent C. parasitica strains in chestnut populations, we determined the incidence of hypovirulence in the central part of the country. Seventy eight isolates of the filamentous ascomycete C. parasitica were collected from 2004 to 2006, from four populations (Markuševac1, Markuševac2, Samobor, Sljeme). Thirty four of them had white morphology, 19 intermwdiate, and 25 orange. Twenty six isolates (21 white, 2 intermediate and 3 orange) were tested for the presence of double stranded RNA (dsRNA) by cellulose chromtography and electrophoresis on agarose gels. Hypoviral dsRNA of approximately 12.7 kb in lenght was detected in all the white isolated tested. In 4 isolates M-dsRNA was also detected. The identity of the hypoviral isolates was determined by reverse transcription, polymerase chain reaction of two hypoviral open reading amplified products showed little variation among the examined hypoviruses from Croatia. Six patterns were completely identical with that of a hypoviral isolate from a fungus collected in Croatia 22 years ago. Phylogenetic analysis based on the restriction patterns grouped all hypoviruses from Croatia to the subtype I of CHV-1.

Hypovirus, dsRNA, RFLP, Cryphonectria parasitica, fungal virulence

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