engleski

Chestnut genotype plays a significant role in the recovery from chestnut blight disease

Chestnut blight is caused by an aggressive ascomycete Cryphonectria parasitica, which was introduced from Asia to Europe in XX century. The Asian chestnut species are tolerant to this pathogen, but in Europe C. parasitica has been continuously reducing the number and yield of Castanea sativa trees for decades. The emergence of naturally occurring dsRNA virus, Cryphonectria hypovirus 1 (CHV1), reduces fungal virulence and its capacity to reproduce via spores ; causing the phenomenon called hypovirulence. As a consequence, naturally growing C. sativa trees infected with hypovirulent strains of fungus usually recover or show much weaker symptoms of infection. A relatively high frequency of hypovirulent strains of the fungus and, consequently, recovered chestnut trees were observed in Croatian forest populations. However, „Lovran marrons“, a special breed of chestnuts primarily grown for the production of large, high quality fruits, do not seem to recover. A substantially higher incidence of aggressive, expanding cankers was observed on the marrons than on the naturally-growing trees, although there was no significant difference between the population structures of C. parasitica isolates from marrons and those from naturally growing trees in regard to vegetative incompatibility types or CHV1 prevalence. Furthermore, the chestnuts and marrons were of the same age and growing intermixed in the same area, nullifying physiological and/or ecological factors that might influence the recovery of the trees. Therefore, it seems that the marron genotype is especially vulnerable and its ability to recover is limited even when CHV1 is widespread in C. parasitica population.

chestnut; Cryphonectria parasitica; genotype; hypovirulence

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