Climate, host and geography shape insect and fungal communities of trees.

Non-native pests, climate change, and their interactions are likely to alter relationships between trees and tree-associated organisms with consequences for forest health. To understand and predict such changes, factors structuring tree-associated communities need to be determined. Here, we analysed the data consisting of records of insects and fungi collected from dormant twigs from 155 tree species at 51 botanical gardens or arboreta in 32 countries. Generalized dissimilarity models revealed similar relative importance of studied climatic, host-related and geographic factors on differences in tree-associated communities. Mean annual temperature, phylogenetic distance between hosts and geographic distance between locations were the major drivers of dissimilarities. The increasing importance of high temperatures on differences in studied communities indicate that climate change could affect tree-associated organisms directly and indirectly through host range shifts. Insect and fungal communities were more similar between closely related vs. distant hosts suggesting that host range shifts may facilitate the emergence of new pests. Moreover, dissimilarities among tree-associated communities increased with geographic distance indicating that human-mediated transport may serve as a pathway of the introductions of new pests. The results of this study highlight the need to limit the establishment of tree pests and increase the resilience of forest ecosystems to changes in climate

Culturable Endophytic Fungi in Fraxinus excelsior and Their Interactions with Hymenoscyphus fraxineus

The species diversity of culturable endophytic fungi was studied in the leaves and twigs of symptomatic and asymptomatic Fraxinus excelsior trees. Endophytic mycobiota was dominated by Ascomycota species, with Pleosporales (44.17%) and Diaporthales (23.79%) endophytes being the most frequently observed in the tree samples. The number of endophytic isolates and species richness varied depending on the sampling date (May and October) and tissue location. Of the 54 species identified based on ITS sequences, 14 were classified as dominant. The most frequently isolated species were Diaporthe eres, followed by Alternaria alternata, Dothiorella gregaria, and Fraxinicola fraxini. The inhibitory effect of 41 species (75 isolates) of endophytes on the radial growth of a Hymenoscyphus fraxineus isolate was studied under in vitro conditions (dual cultures). The radial growth of H. fraxineus was the most inhibited by four endophytic fungi from twigs (Fusarium lateritium, Didymella aliena, Didymella macrostoma, and Dothiorella gregaria). The inhibitory effect of the four isolates was also studied under in planta conditions. The isolates artificially inoculated into the trunks of ash trees reduced the length of necroses formed by H. fraxineus co-inoculated in the same trunks. This effect depended on the isolate, and the inhibition was most prominent only on trunks inoculated with F. lateritium and D. aliena. Although the total length of necrotic lesions formed by the H. fraxineus infection was shorter in the ash trunks co-inoculated with the endophytes, the difference was not significant

The determination of microscopic fungi from chestnut (Castanea sativa Mill.) fruits, leaves, crust and pollen

Ve čtyřech slovenskych regionech byly studovany vztahy medzi rostlinou a mikroorganismy s ohledem na stanoveni mykofl ory u Castanea sativa Mill. (ořechy, kůra, listi a pyl) a jejich vliv na hostitelsky organismus. V experimentech bylo izolovano 7 rodů a 10 druhů mikroskopickych hub z ořechů, kůry a listi. Bylo zjištěno, že izolaty z pylu Castanea sativa Mill. byly zastoupeny osmi rody a jedenacti druhy mikroskopickych hub. U izolatů ořechů se nejčastěji vyskytovaly druhy Alternaria alternata (36,4%), Cladosporium cladosporioides (43,7%), Fusarium oxysporium (23,8 %) a Rhizopus stolonifer (22,2%). U izolatů listů se nejčastěji vyskytovaly druhy Alternaria alternata (49,7%) a Cladosporium cladosporioides (34,7%) a kůry se nejčastěji vyskytovaly druhy Alternaria alternata (35,1%) a Cladosporium cladosporioides (35,9%). Druhy Alternaria alternata (54,8%) a Cladosporium cladosporioides (50,9%) byly nejčastěji vyskytujici se mikroskopicke houby pylu. Na zakladě dalšich taxonomickych určeni z rodů Aspergillus byly izolovany a identifi kovany zastupci druhů A. fl avus, A. fumigatus, A. ochraceus, A. terreus a A. versi. Z rodu Fusarium byl izolovan druh F. oxysporum a z rodu Penicillium byly izolovany druhy P. crustosum a P. glabrum. Zdůrazňujeme, že izolovane rody Aspergillus, Fusarium a Penicillium, jsou považovany za nejvyznamnějši producenty mykotoxinů. Typičti producenti mykotoxinů z rodů Penicillium, Alternaria, Fusarium a Aspergillus byli detekovani na čerstvych ořechach, listech, kůře a pylu při laboratorni teplotě. U všech testovanych časti Castanea sativa Mill. bylo zaznamenano vysoke procento plisňove kontaminace. Rody Alternaria, Cladosporium, Penicillium a Fusarium byly převladajici ve všech izolatech rostliny. Některe z rodů (např. Cladosporium, Alternaria a Penicillium) jsou potencialnimi alergeny, za předpokladu vysoke produkce konidii. Pokročile kaženi ořechů by mohlo mit nepřiznivy učinek na zdravi personalu, ktery naklada s těmito komoditami. Zvlaštni opatřeni by měla byt přijata během sklizně, čištěni, třiděni, baleni, přepravě, skladovani a uvaděni zboži na trh. Chlazeni je důležite pro udrženi kvality a prodlouženi trvanlivosti, i když některe druhy mohou růst při nizkych teplotach. Plody, ktere jsou citlive na nizke teploty, by měly byt uvaděny na trh rychle, aby se zabranilo houbove kontaminaci a potencialni tvorbě mykotoxinů a tim souvisejicimu vzniku zdravotniho rizika.The plant-microbial interactive relations with respect to determination of the mycofl ora of the Castanea sativa Mill. nuts, crust, leaves and pollen and their eff ect on the host organism in four Slovak regions were studied. In the experiments were isolated 7 genera and 10 species of microscopic fungi from the nut, crust and leaves. It was found, that isolates from the Castanea sativa Mill. pollen were represented by 8 genera and 11 species of microscopic fungi. Alternaria, Cladosporium, Mucor and Rhizopus appeared to be the most frequently occurring genera of nuts, leaves and crust. Acremonium, Alternaria, Cladosporium, Fusarium, Penicillium and Trichoderma are the most frequently fungi of pollen. On the base of further taxonomic determination from the genera Aspergillus were isolated and identifi ed representatives of species A. fl avus, A. fumigatus, A. ochraceus, A. terreus and A. versicolor. From the genera Fusarium was isolated F. oxysporum and from Penicillium genera were isolated P. crustosum and P. glabrum. It is necessary to underline that the isolated genera Aspergillus, Fusarium and Penicillium are considered as the most important producers of mycotoxins

Culturable Endophytic Fungi in <i>Fraxinus excelsior</i> and Their Interactions with <i>Hymenoscyphus fraxineus</i>

The species diversity of culturable endophytic fungi was studied in the leaves and twigs of symptomatic and asymptomatic Fraxinus excelsior trees. Endophytic mycobiota was dominated by Ascomycota species, with Pleosporales (44.17%) and Diaporthales (23.79%) endophytes being the most frequently observed in the tree samples. The number of endophytic isolates and species richness varied depending on the sampling date (May and October) and tissue location. Of the 54 species identified based on ITS sequences, 14 were classified as dominant. The most frequently isolated species were Diaporthe eres, followed by Alternaria alternata, Dothiorella gregaria, and Fraxinicola fraxini. The inhibitory effect of 41 species (75 isolates) of endophytes on the radial growth of a Hymenoscyphus fraxineus isolate was studied under in vitro conditions (dual cultures). The radial growth of H. fraxineus was the most inhibited by four endophytic fungi from twigs (Fusarium lateritium, Didymella aliena, Didymella macrostoma, and Dothiorella gregaria). The inhibitory effect of the four isolates was also studied under in planta conditions. The isolates artificially inoculated into the trunks of ash trees reduced the length of necroses formed by H. fraxineus co-inoculated in the same trunks. This effect depended on the isolate, and the inhibition was most prominent only on trunks inoculated with F. lateritium and D. aliena. Although the total length of necrotic lesions formed by the H. fraxineus infection was shorter in the ash trunks co-inoculated with the endophytes, the difference was not significant