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ŠUMARSKI LIST 3-4/2019 str. 12     <-- 12 -->        PDF

species specific primers for PCR amplification either, as there were no visible PCR products on agarose gels besides positive controls included in each reaction.
With total of 15 different fungal taxa present in less than 40% of samples (in 58 out of 160 in total), narrow-leaved ash seeds revealed relatively good health status in comparison with common ash (Fraxinus excelsior) seeds analysed in similar European studies, where larger number of taxa were identified in smaller number of samples and with averagely higher individual presence frequency (Cleary et al. 2013, Hayatgheibi 2013).
Species of the most frequently detected genus in this research, Alternaria sp., haven’t caused visible symptoms on seeds although the identified Alternaria alternata and Alternaria tenuissima are reported as seed pathogens on Betula spp. and Robinia pseudoacacia L. (Lilja 1979, Sunita 1998) and causative agents of Malus spp. and Punica granatum L. fruit rot during storage (Zambounis et al. 2015). Alternaria alternata has also been found in symptomatic bark, wood and buds of declining Fraxinus excelsior (Pukacki and Przybył 2005, Davydenko et al. 2013, Kowalski et al. 2016), indicating that it can act as an opportunistic pathogen in already declining ash tissue, possibly in the narrow-leaved ash seeds as well if they are under the influence of negative biotic and abiotic factors while on a tree or stored in unfavourable conditions after the harvest. Other frequently detected species, Sphaerulina berberidis, has so far been reported only as leaf endophyte of several tree species (Eo et al. 2014) and most probably has the same role in the narrow-leaved ash seeds since it hasn’t induced any visible symptoms in the analysed samples.
The remainder of identified species in narrow-leaved ash seeds were present in only one to three samples, but included some of the well known tree pathogens such as Phomopsis velata (synonym Diaporthe eres) and Botryosphaeria stevensii (synonym Diplodia mutila), which were also found in Fraxinus excelsior seeds in Latvia and Sweden (Cleary et al. 2013). Former is known for causing stem canker and dieback of several tree species (Quaroni et al. 1980, Anagnostakis 2007, Thomidis and Michailides 2009), fruit deterioration (Ristić et al. 2016) and being present in necrotic tissue and collar rots of Fraxinus excelsior (Kowalski et al. 2016, Langer 2017). Latter is known as a parasite involved in bark necrosis, canker formation and dieback of Fraxinus excelsior and Fraxinus ornus L., Quercus spp. and other tree species (Ragazzi et al. 1999, Przybył 2002, Sidoti and Granata 2004, Sims et al. 2016). Some of identified species are reported to be seed or fruit pathogens on other plant species, like Fusarium oxysporum on Robinia pseudoacacia seeds (Sunita 1999), Cladosporium cladosporioides on tobacco seeds (Nicotiana tabacum L.) (Wang et al. 2014) and stored hazelnuts (Corylus avellana L.) (Moghaddam and Taherzadeh 2007), and Cladosporium herbarum on stored figs (Ficus carica L.) (Montealegre et al. 2000) and Prunus spp. fruits (Tonini and Capriotti 1996). Venturia fraxini, known primarily as endophyte (Schlegel et al. 2016), but