engleski

Selection of Cryphonectria parasitica hypovirulent isolates suitable for biological control in Croatia

Chestnut blight, caused by the fungus Cryphonectria parasitica, is responsible for decline of chestnut stands in Croatia. C. parasitica can be infected with hypoviral double-stranded RNA (dsRNA) which reduces its virulence and therefore has the potential for biological control. Since disease is successfully controlled by hypovirulence we wanted to select hypovirulent isolates which could be used for biological control. A total of 338 isolates of C. parasitica were sampled from 10 chestnut Croatian populations. The highest incidence of hypovirulent isolates was observed in continental part of the country (66.6%), while hypovirulence was low in the coastal part of Croatia (12.7%). A sample of 36 Croatian hypovirus isolates was characterized using RT-PCR, RFLP analyses and sequencing. To choose the virus isolate which causes optimal reduction of fungal growth, virulence and reproductive capacities, growth and sporulation of 31 hypovirulent and 4 virulent isolates were estimated in vitro. Unfortunately, there was no statistical difference between the growth and sporulation of most of the C. parasitica isolates infected with CHV-1 subtype I and virus-free isolates, when tested in vitro. Only one virus isolate from Cres reduced the fungal growth statistically and is therefore suitable for biological control. For the estimation of other hypovirus isolates further in vivo studies are necessary.

Castanea sativa; chestnut blight; growth; hypovirulence; sporulation

Hrvatski i engleski