Data di Pubblicazione:
2005
Citazione:
Genetic similarity of flag shoot and ascospore subpopulations of Erysiphe necator in Italy / P. Cortesi, A. Mazzoleni, C. Pizzatti, M.G. Milgroom. - In: APPLIED AND ENVIRONMENTAL MICROBIOLOGY. - ISSN 0099-2240. - 71:12(2005), pp. 7788-7791. [10.1128/AEM.71.12.7788-7791.2005]
Abstract:
The overwintering mode of the grape powdery mildew fungus, Erysiphe necator (syn. Uncinula necator), as mycelium in dormant buds (resulting in symptoms known as flag shoots) or as ascospores in cleistothecia,
affects the temporal dynamics of epidemics early in the growing season. We tested whether distinct genetic groups (I and III) identified previously in E. necator correlate to overwintering modes in two vineyards in Tuscany, Italy, to determine whether diagnostic genetic markers could be used to predict overwintering.
Samples from one vineyard were collected from flag shoots; the other vineyard, 60 km away, had no flag shoots,
and mildew colonies were assumed to be derived from ascospores. Genetic markers putatively diagnostic for
groups I and III showed that both types were common in the flag shoot subpopulation. Both genetic types were
found in the ascospore population, although group III was dominant. We did not find strong genetic differentiation
between the two subpopulations based on inter-simple sequence repeat markers. Although there was
significant (P < 0.001) genetic differentiation between these subpopulations in 1997 and when 1997 and 1998
subpopulations were pooled ( 0.214 and 0.150, respectively), no differentiation was evident between
vineyards in 1998 ( 0.138, P 0.872). Moreover, we did not observe distinct lineages corresponding to
overwintering modes, as observed in previous studies. We could not determine if differentiation resulted from
biological differences or restricted gene flow between the two vineyards. Our samples were taken from both
subpopulations early in the epidemic, while previous studies confounded overwintering mode and sampling
time. These results do not support a strong correlation between overwintering and genetic groups, highlighting
the need to base population biology studies on sound biological and epidemiological knowledge.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Population genetics ; overwintering ; downy mildew ; vitis vinifera
Elenco autori:
P. Cortesi, A. Mazzoleni, C. Pizzatti, M.G. Milgroom
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