Phenotypic and histochemical traits of the interaction between Plasmopara viticola and resistant or susceptible grapevine varieties
Articolo
Data di Pubblicazione:
2012
Citazione:
Phenotypic and histochemical traits of the interaction between Plasmopara
viticola and resistant or susceptible grapevine varieties / S.L. Toffolatti, G. Venturini, D. Maffi, A. Vercesi. - In: BMC PLANT BIOLOGY. - ISSN 1471-2229. - 12(2012 Aug 01), pp. 124.124-124.139.
Abstract:
Grapevine downy mildew, caused by Plasmopara viticola, is a very serious disease affecting
mainly Vitis vinifera cultivated varieties around the world. Breeding for resistance through
the crossing with less susceptible species is one of the possible means to reduce the disease
incidence and the application of fungicides. The hybrid Bianca and some of its siblings are
considered very promising but their resistance level can vary depending on the pathogen
strain. Moreover, virulent strains characterized by high fitness can represent a potential threat
to the hybrid cultivation.
The host response and the pathogen virulence were quantitatively assessed by artificially
inoculating cv Chardonnay, cv Bianca and their siblings with P. viticola isolates derived from
single germinating oospores collected in various Italian viticultural areas. The host
phenotypes were classified as susceptible, intermediate and resistant, according to the Area
Under the Disease Progress Curve caused by the inoculated strain. Host responses in cv
Bianca and its siblings significantly varied depending on the P. viticola isolates, which in turn
differed in their virulence levels. The fitness of the most virulent strain did not significantly
vary on the different hybrids including Bianca in comparison with the susceptible cv
Chardonnay, suggesting that no costs are associated with virulence. Among the individual
fitness components, only sporangia production was significantly reduced in cv Bianca and in
some hybrids. Comparative histological analysis revealed differences between susceptible
and resistant plants in the pathogen diffusion and cytology from 48 h after inoculation onwards. Defence mechanisms included callose depositions in the infected stomata, increase
in peroxidase activity, synthesis of phenolic compounds and flavonoids and the necrosis of
stomata and cells immediately surrounding the point of invasion and determined alterations in
the size of the infected areas and in the number of sporangia differentiated.
Some hybrids were able to maintain an intermediate-resistant behaviour even when
inoculated with the most virulent strain. Such hybrids should be considered for further field
trials.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Disease resistance; Oomycetes; Pathogen fitness
Elenco autori:
S.L. Toffolatti, G. Venturini, D. Maffi, A. Vercesi
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