FIRST RECORDS OF TELEOMORPH OF AN INVASIVE FUNGUS ERYSIPHE MACLEAYAE (ERYSIPHALES) IN UKRAINE

It is reported that in 2015 an invasive powdery mildew fungus, Erysiphe macleayae (Erysiphales, Ascomycota), formerly known in Ukraine only in its anamorph stage, began to form mature fruiting bodies on Chelidonium majus and Macleaya microcarpa (Papaveraceae). Morphologically, they are almost identical to the chasmothecia of Slovak specimens. Ukrainian materials are also similar to E. macleayae samples described from China although having slightly larger chasmothecia and slightly smaller asci and ascospores. Teleomorph of the fungus was found in three localities in the city of Kiev and Kiev Region. Another species of Macleaya, M. cordata, was infected only by the anamorph of E. macleayae. The specimens studied are stored in the National Herbarium of M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine (KW). The authors assume that formation of fruiting bodies of E. macleayae may be caused by an extremely hot summer in 2015. Another possible explanation is that a new biotype of E. macleayae has migrated from South Asia into Ukraine and subsequently formed mature chasmothecia through the sexual process with the indigenous European populations of the fungus.


Materials and methods
In the autumn of 2015, powdery mildew samples on Chelidonium majus and Macleaya microcarpa, which contained not only mycelium, conidia and conidiophores, but also fruiting bodies, were collected in Kyiv and Kyiv Region.At the same time, on M. cordata only anamorphic stage of this fungus was found.The studied materials are listed below, following the characteristics of E. macleayae anamorph and teleomorph.The specimens are stored in the National Herbarium of M.G.Kholodny Institute of Botany, National Academy of Sciences of Ukraine (KW).The fungus was studied and photographed under a light microscope «Primo Star» (Carl Zeiss, Germany) with the camera «Canon A 300» and the software «AxioVision 4.7».Only herbarium specimens were used.The mycelium, conidiophores and conidia removed from the surface of infected leaves by a transparent adhesive tape.To restore shape and size, a piece of tape with these fungus structures was put in a droplet of 40 % lactic acid solution on a microscope slide (sticky side up), covered with a cover glass, gently heated to boiling point, then examined under the light microscope.Chasmothecia were prepared and studied in a drop of distilled water.
Digital data were treated statistically when n was ≥ 30 for each character.

Results and discussion
As noted by R. Cook and U. Braun (2012), E. macleayae is characterized by very small fruiting bodies with long appendages and large ascospores.Morphologically, Ukrainian materials are almost identical to Slovak specimens of this fungus, which have recently been reported by Pastirčáková et al. (2016).Our samples are also close to the specimens of E. macleayae described from China (Zheng, Chen, 1981) although having slightly larger chasmothecia and smaller asci and ascospores.Below are description of the holomorph of the fungus and corresponding illustrations (Figure).Sydowia 34: 290. 1981 Mycelium at first greyish, very thin, not conspicuous, mostly on the upper side of the leaf, on the underside almost absent, then forming circular to irregular white patches, later confluent, also on stems and infructescences.Hyphae branched, septate, hyaline, thin-walled.Hyphal appressoria two times lobed to nipple-shaped, solitary or opposite doubled.Conidiophores erect, 80-145 μm, mainly 3-or 4-cell, foot-cells some flexuous, 20-30 × 6-8 μm, producing conidia singly, Pseudoidium type.Conidia elongated ellipsoid, almost cylindrical or cylindrical, hyaline, without fibrosin bodies, 32-53 × 8.5-16 μm, length to width ratio 2.2-4.8, with the mesh surface.Chasmothecia mostly gregarious or of a continuous layer on the upper side of the leaf, less often scattered on the lower side of the leaf, petioles and sometimes stalks (on C. majus), or mainly on the lower side of the leaf in diffuse groups (on M. microcarpa), hemispherical, depressed below, 80-109 μm diam.
In 2015, we made a comparative study of E. macleayae on C. majus and M. cordata.As a result, it was determined that dynamics of the affection of these hosts was somewhat different.Thus, on the former host the mycelium of the fungus appears much earlier than on the latter.Symptoms of powdery mildew lesions were observed on C. majus in early July, while on M. cordata only in early September.First, the fungus infected mostly the upper side of leaves of C. majus, then in the period of seed formation it spread to the stem.Fruit bodies formed in early September on both sides of the lower, older leaves of plants.They first appeared on leaflets, located closer to the base of the petioles and much less on the base of leafstalks.Typically, on the upper leaflets fruiting bodies are missing.On M. cordata, the fungus first developed mainly on the upper side of the leaves of the lower tier, then also on the flowering part of the stem.Chasmothecia were not formed.In addition, a slight difference in the shape of conidia of the fungus on these hosts was noticed.Thus, the ratio of length to width for C. majus averaged 2.5, whereas for M. cordata 2.2.However, these indicators fit well within the scope of this feature variation (2.2-4.8)shown previously for Ukrainian material (Heluta, Kravchuk, 2015).
There were some differences in the formation of fruiting bodies on C. majus and M. microcarpa.On the former host, they developed mainly on the upper side of the leaf as a continuous layer ( latter mainly on the lower side, in the form of diffuse spots (Figure , d).
The authors can not reliably explain why E. macleayae, which for many years developed only anamorphic stage in Europe, with one exception on Meconopsis cambrica (L.) Vig., began to form fruiting bodies.We have already noted similar cases for other powdery mildews.For example, the anamorph of East Asian E. arcuata U. Braun, V.P. Heluta & S. Takam.was recorded by one of the authors of this article in 1977 (Heluta, 1989).However, the fungus began intensively to form fruiting bodies, simultaneously in different parts of Europe, only in 2005 (Braun et al., 2006).We can propose two hypotheses concerning the cause of the development of E. macleayae teleomorph.Presumably formation of fruiting bodies of this fungus was provoked by the extremely hot summer in 2015.If this assumption is correct, then obviously in cooler seasons the fungus will again develop exclusively anamorph.Another possible explanation is that a new biotype of E. macleayae has migrated from South Asia into Ukraine and subsequently formed complete chasmothecia through the sexual process with the indigenous European populations of the fungus.In this case, fruiting bodies in the future will be observed annually.