Microsatellite markers for population studies of the ascomycete Phyllosticta ampelicida, the pathogen causing grape black rot

Grape black rot, caused by the homothallic ascomycete Phyllosticta ampelicida, is a disease originating from North America and is widespread in Europe. To investigate population structure and epidemics of this pathogen, we developed 11 microsatellite markers. A multiplex PCR assay was used to amplify genomic DNA from environmental samples including mummified berries and foliar lesions, and from fungal cultures. Environmental samples were collected from five countries (Switzerland, France, Germany, Luxembourg and the USA), and consisted of 64 different genotypes. Five additional genotypes were identified from pure cultures isolated in Switzerland and Germany. The allele rarefaction approach indicated that French vineyards in the region of Bordeaux displayed the greatest mean allelic richness, probably related to the fact that France is the country where the disease was first reported outside North America, in 1885. Our results also suggest the absence of links between the species/cultivar of Vitis hosts and the infecting P. ampelicida genotypes. This is the first report of development of microsatellite markers and their deployment for population studies of P. ampelicida.ISSN:0031-9465ISSN:1593-209

Historical museum specimens reveal the loss of genetic and morphological diversity due to local extinctions in the endangered water chestnut Trapa natans L. (Lythraceae) from the southern Alpine lake area

Freshwater aquatic plants have increased extinction risks due to strong human pressure and the patchy nature of their habitats. However, their unclear population structure frequently hinders conservation planning. To investigate population subdivision and risks to long-term survival of such species, we combined genetic, morphometric and biogeographical approaches to the example of the endangered water chestnut Trapa natans (Lythraceae) from the southern Alpine lake area (Insubria). Amplified fragment length polymorphism (AFLP) of seven extant local stands revealed similar and intermediate levels of genetic diversity, of which c. 97% was partitioned within lakes. Thus, no signs of strong genetic drift and associated loss of genetic diversity were found, despite a reduction of c. 52% of local populations since the early 19th century. Nuclear ribosomal sequences (ITS1-5.8S rRNA-ITS2) combined with a morphometric study of nuts (based on fresh and historical museum material) revealed the presence of two genetically and morphologically slightly distinct lineages, one of which went extinct during the 20th century after a prolonged period of hyper-eutrophication. Taken together, our results indicate the current presence of one large Insubric Trapa population. To prevent genetic risks to survival associated with small population size and increasing fragmentation due to past extinctions, freshwater managers should preserve the large census sizes still present in many Insubric lakes and reduce eutrophication

Historical museum specimens reveal the loss of genetic and morphological diversity due to local extinctions in the endangered water chestnut Trapa natans L. (Lythraceae) from the southern Alpine lake area

Freshwater aquatic plants have increased extinction risks due to strong human pressure and the patchy nature of their habitats. However, their unclear population structure frequently hinders conservation planning. To investigate population subdivision and risks to long-term survival of such species, we combined genetic, morphometric and biogeographical approaches to the example of the endangered water chestnut Trapa natans (Lythraceae) from the southern Alpine lake area (Insubria). Amplified fragment length polymorphism (AFLP) of seven extant local stands revealed similar and intermediate levels of genetic diversity, of which c. 97% was partitioned within lakes. Thus, no signs of strong genetic drift and associated loss of genetic diversity were found, despite a reduction of c. 52% of local populations since the early 19th century. Nuclear ribosomal sequences (ITS1-5.8S rRNA-ITS2) combined with a morphometric study of nuts (based on fresh and historical museum material) revealed the presence of two genetically and morphologically slightly distinct lineages, one of which went extinct during the 20th century after a prolonged period of hyper-eutrophication. Taken together, our results indicate the current presence of one large Insubric Trapa population. To prevent genetic risks to survival associated with small population size and increasing fragmentation due to past extinctions, freshwater managers should preserve the large census sizes still present in many Insubric lakes and reduce eutrophication