Indagini epidemiologiche, fenotipiche e genotipiche di popolazioni del fungo Cryphonectria parasitica nel comprensorio dei Monti Cimini
Author(s)
Pasquini, Barbara
Date Issued
February 27, 2009
Type
Doctoral Thesis
Abstract
Cryphonectria parasitica, the causal agent of the chestnut blight, is one of the major disease of
chestnut trees worldwide also the cause of the decline of the chestnut in the Monti Cimini areas.
The frequency of normal and altered phenotypes did not changed consistently in the last 20 years,
suggesting that sexual reproduction is strongly limited or absence. However, the study of vegetative
compatibility revealed the presence of six groups of compatibility present typically, some only in
Northern Italy and others in South Italy alone and bearing each five polymorfic loci feature that, in
the case of sexual reproduction potentially would allow the differentiation of new v-c groups in the
investigated populations. The aims of this work are: assessing the reproductive ability of the fungus
in field, through the verification of the production of gamic reproduction and their vitality structures
determining the number of present compatibility in the offspring of the perithecia groups and study
the genetic variability; the presence of both sexual mating type was finally analysed and the
presence of heterocaryon.
Results indicate a constant presence of stromata with perithecia on "deadly cancers. The analysis of
the vitality of the perithecia, showed a remarkable capacity of maturation of the peritechia and
expulsion of the produced ascospores. The quantification of the ascospores and their ability to
germination have however shown in all cases limited. The vegetative compatibility tests between
the offspring of the perithecia obtained, showed segregation between all the tested progeny and the
analysis of vegetative compatibility European groups showed a similar distribution to that obtained
from previous work. Both mating types were found in all perithecia, making potentially possible
recombination trought sexual reproduction. The majority of the analysed perithecia also shows the
presence of heterocaryon. Results indicate a still stationary situation, but the presence of sexual
reproduction and sexual both structures maintain high risk of resurgence of the disease to the
differentiation of new vc-types trought sexual recombination or introduction from new areas.
Hopefully then a regulation throught forestry activities and trading of chestnut products between
areas with different populations of the fungus.
Additional information
Dottorato di ricerca in Protezione delle piante
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