Persistence and spatial autocorrelation of clones of Erysiphe necator overwintering as mycelium in dormant buds in an isolated vineyard in northern Italy
Articolo
Data di Pubblicazione:
2008
Citazione:
Persistence and spatial autocorrelation of clones of Erysiphe necator overwintering as mycelium in dormant buds in an isolated vineyard in northern Italy / P. Cortesi, C. Pizzatti, D. Bertocchi, M.G Milgroom. - In: PHYTOPATHOLOGY. - ISSN 0031-949X. - 98:2(2008), pp. 148-152. [10.1094/PHYTO-98-2-0148]
Abstract:
The population structure of the grape powdery mildew fungus, Erysiphe necator (formerly Uncinula necator), has been hypothesized to vary from being clonal to highly diverse and recombining. We report here on the structure of an E. necator population sampled during a 4-year period from an isolated vineyard in northern Italy (Voghera, Pavia
Province). We obtained 54 isolates of E. necator that overwintered asexually as mycelium in grapevine buds and caused severe symptoms on
the emerging shoots, known as flag shoots. All isolates were genotyped for mating type, four multilocus polymerase chain reaction (PCR)-based
markers (a total of 64 loci were scored), and two single-copy loci designed to identify genetic subgroups in E. necator. All isolates had the
same mating type and single-locus alleles that correlate to isolates from flag shoots in other areas. Only 2 of the 64 loci scored from multilocus
markers were polymorphic; 46 of the 54 isolates had the same multilocus haplotype. Seven isolates had a second haplotype that was recovered over
3 years, and only a single isolate was found with a third haplotype. Both variant haplotypes differed from the main clonal haplotype by single loci. Spatial autocorrelation analyses showed that vines with flag shoots were not aggregated within years, but they were aggregated between consecutive
years. These results demonstrate that this subpopulation of E. necator on flag shoots is composed of a single clonal lineage that has persisted for at least 4 years. We speculate that the lack of diversity in the flag shoot
subpopulation in this vineyard is the result of restricted immigration from surrounding areas and genetic drift operating through founder effects and
periodic bottlenecks. We propose a model that integrates epidemiology and population genetics to explain the variation observed in genetic
structure of E. necator flag shoot subpopulations from different vineyards or viticultural regions.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Oidium tuckeri; Overwintering; Population structure; Vitis vinifera
Elenco autori:
P. Cortesi, C. Pizzatti, D. Bertocchi, M.G. Milgroom
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