Andrias 19 - page 334

270 andrias, 19 (2012)
We can hardly reconstruct the spread of the
fungus in Germany between 2007 and August
2009. We assume, however, that the species has
spread rather slowly and may have reached only
a major part of Baden-Württemberg in September
2009. From 2009 onward, however, the spread of
E. platani could be documented in much detail
and probably better than in any other fungal spe-
cies before in Germany. In 2009 we traced it in
northern Baden-Württemberg (Mannheim) and
in central Baden-Württemberg (Stuttgart), but not
in the south at Lake Constance. Also, the species
could not be recorded in the neighboring states
of Bayern, Hessen and Rheinland-Pfalz the same
year. Negative records were also sent from Nord­
rhein-Westfalen, Saarland and Sachsen-Anhalt.
So most probably, the species had not reached
states other than Baden-Württemberg in 2009.
From this point, the monitoring shown in
Fig. 3 b-d documents the spread of this fungus in
Germany. Considering the northernmost records
in 2009 (Mannheim, Baden-Württemberg) and
in 2011 (Arendsee, Sachsen-Anhalt) the fungus
progressed appr. 190 km/year, i.e. much faster
than in the previous years. Given, that the fungus
was introduced in SW Germany and wandered
also northward to Sachsen-Anhalt, the spread
is even 215 km/year. For powdery mildews with
woody plant hosts, this fast progressing is not
exceptional. We know from powdery mildew epi-
demic spreads of the 19th and the first part of the
20th century (see compilation and description in
Blumer 1967) and more recently introduced spe-
cies such as the elder powdery mildew Erysiphe
vanbruntiana var. sambuci-racemosae (U. Braun)
U. Braun & S. Takam. (Scholler 1996 as Micro-
sphaera sambucicola Henn.) that other powdery
mildews may progress even faster.
Kirschner (2011) provided two possible explana-
tions for the sudden migration northward: Firstly,
the global warming as it is assumed for many
other migrating southern fungal species (e.g.
Scholler & Müller 2008) and secondly, the for-
mation of fruitbodies which are better adapted
to overwintering than mycelium or conidia. They
were first recorded between 2000 and 2002 in
Montenegro (Ranković 2003), in 2006 in Hungary
(Pastirčáková & Pastirčák 2008) and finally 2007
in Switzerland (Fischer et al. 2008) and in Ger-
many. So migrating northward goes along with
the formation of the sexual state. We agree with
this and considering our results we expect this
species to appear in the northernmost European
plane plantations within the next years.
Phylogenetic placement
Molecular phylogenetic analyses of the ITSclearly
place Erysiphe platani within Erysiphe, however,
they do neither resolve well the placement of E.
platani within Erysiphe nor reveal any groups of
species that can be correlated with morphologi-
cal traits or relatedness of host plants.
Fig. 2 shows E. platani forming a subclade to-
gether with three other Erysiphe spp. (E. elevata,
E. magnifica, and E. syringae) on woody plants
of three different families formerly placed in the
genus Microsphaera. This subclade, however,
received only very low support. Many Erysiphe
species have recurved dichotomous branchings
at the end of the fruitbody appendages, so do
all species of this subclade. However, species
previously accommodated in Microsphaera (see
Braun & Takamatsu 2000) and/or having woody
plant hosts also occur in other clades. This has
already been found by previous authors (e.g.
Takamatsu et al. 1999).
Analyses of ITS sequence data may not be suit-
able for resolving the phylogeny of Erysiphe.
However, the analyses including specimens
from distant places in Europe, the USA (Saenz
& Taylor 1999), and Australia (Cunnington et al.
2003) show that Erysiphe platani can clearly be
distinguished by its ITS sequence from other – in
several cases – morphologically similar Erysiphe
species (e.g. E. alphitoides, E. magnifica, E. or-
nata, E. syringae, E. wallrothii). That is in line with
Schoch et al. (2012) who proposed the ITS as
universal DNA barcode marker for fungi.
The genetic distance of Erysiphe platani to its
closest relatives of which ITS sequences are
available is considerable. That may be explained
by a high phylogenetic age of the species, a high
mutation rate or simply by missing data of the
closest relatives.
The relatively high variability of the ITS of speci-
mens from different geographic regions (up to
five bp in four loci) points at the potential of the
ITS as marker in mycogeographical studies of
spreading powdery mildews.
Acknowledgements
We thank the many collaborators for the monitoring of
Erysiphe platani (names listed in chapter 2.2), Alexan ­
dra Pintye for providing literature and Walter Gams and
Roland Kirschner for reviewing the manuscript and
Michael Weiss, Sigisfredo Garnica and Robert Bauer
for providing the molecular lab.