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(a) Mycelium of Allantophomopsis cytisporea colonizing dead tissue of a Calluna vulgaris leaf (scale bar: 20 µm); the bright meandering lines are the cell walls of the puzzle piece-like epidermal cells of C. vulgaris. (b) Interaction between Herpotrichia pinetorum (strain 95-Fi; Schneider et al. 2009) to the left and A. cytisporea (strain A_DA_21_15) to the right after 21 days at 4°C on MEA. Conidia of A. cytisporea strains (c) A_SB_8_12 and (d) A_SB_6_12 in H 2 O stained with fountain pen ink (Pelikan, blue) and observed using phase contrast optics (scale bar: 10 µm); arrowheads indicate the slimy appendages of the conidia.
Source publication
Shoots of Calluna vulgaris, Erica carnea, Juniperus communis subsp. nana, Picea abies, and Pinus mugo subsp. mugo covered with felty, melanized epiphytic mycelia typical for brown felt blight caused by Herpotrichia pinetorum were collected at several locations in the Swiss Alps. Most cultures prepared from the mycelia on J. communis subsp. nana and...
Contexts in source publication
Context 1
... closer look at these shoots revealed the presence of mycelial fragments indicative of the former presence of mycelial mats (Figures 1e, 1f). In addition, examination of leaves under the light microscope showed presence of melanized, septate mycelium on and within the leaves (Figure 2a). Incubation of such leaves usually led to the emergence of A. cytisporea. ...
Context 2
... dimensions did not differ significantly among strains (4.9-7.8 × 1.9-3.0 µm; mean: 6.2 × 2.5 µm) and corresponded well with those of the conidia of A. cytisporea (6-8 × 2-2.5 µm; Carris 1990) and A. lunata (6-9 × 2-3.5 µm; Nag Raj 1993) (Figures 2c, 2d). The conidia of A. lycopodina did not fit because these are distinctly longer and measure (7-)8-15(-17) × 2-3.5 µm (mean: 11.2 × 2.9 µm; Carris 1990). ...
Context 3
... cytisporea did not grow at 28°C or higher, and temperatures 35°C and higher were lethal. Interaction of the two species on MEA at 4°C showed a strong antibiotic effect of H. pinetorum against A. cytisporea expressed by a distinct inhibition zone (Figure 2b). A similar effect was observed at 20°C. ...
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... can now be added to the list of hosts. Extented networks of melanized mycelium of A. cytisporea can be observed in and on dead leaf tissue (Figure 2a). Interestingly, Pietrowski, Flessa, and Rambold (2012) isolated an Allantophomopsis species as an endophyte from C. vulgaris leaves that possesses an ITS identical to that of A. cytisporea strain A_AR_1_06 isolated by Schneider et al. (2009) from an epiphytic mycelial mat on J. communis subsp. ...
Citations
... Petr. is reported to be associated with the snow blight of Calluna vulgaris and Pinus mugo subsp. mugo in the mountainous region in Switzerland, but the pathogenicity is not proven (Sieber 2019). This species is also known to be associated with postharvest disease with some other host species. ...
Gremmenia abietis (Dearn.) Crous (syn: Phacidium abietis) was originally described in North America to accommodate the species associated with snow blight of Abies and Pseudotsuga spp. In Japan, this species was first observed on the dead needles on Abies sachalinensis and Picea jezoensis var. jezoensis in 1969. However, the identity of Japanese species was unclear due to the lack of molecular data and the absence of anamorph description. In this study, we collected fresh specimens from various conifer species (A. sachalinensis, A. veitchii, Pic. jezoensis var. jezoensis, Pic. jezoensis var. hondoensis, Pinus koraiensis, and Pin. pumila) in Japan and revised the taxonomy based on morphological and phylogenetic analyses. Phylogenetic analyses based on nuc rDNA internal transcribed spacer ITS1-5.8S-ITS2 (ITS), nuc 28S rDNA (28S), and RNA polymerase II second largest subunit (RPB2) regions indicated that the species belongs to Phacidiaceae. Conidiomata formed in vitro produced pyriform, hyaline conidia without mucoid appendage, which distinguished the species from phylogenetically related genera. Consequently, we established Chionobium takahashii to accommodate the snow blight fungus in Japan. Further phylogenetic analyses also indicated that C. takahashii includes several distinct clades corresponding to the host genera (Abies, Picea, Pinus). Morphological differences among those clades were unclear, suggesting that C. takahashii may contain host-specific cryptic species.
... One of the most important diseases is brown felt blight caused by Herpotrichia juniperi, which can lead to destruction of natural regenerations in large areas, especially when thick snow cover persists for a long time [13,14]. In places, similar symptoms are caused by Allantophomopsis cytisporea [15]. In some mountain sites the dieback of P. mugo is largely due to the fungi of the genus Armillaria and Heterobasidion, which infect plant roots and cause their rot [16,17]. ...
... Aerial hyphae were hyaline to olive-brown, 2.0 to 7.5 µm thick with circular or oval, intercalary or apical, thin-walled swollen cells 6-17.5 µm in diameter. In the substrate, numerous olive-brown swollen cells, irregular or circular, [8][9][10][11][12][13][14][15][16][17][18][19][20].0 µm in diameter or elongated, 15-25 × 10-12.5 µm were observed. Sexual or asexual morph in vitro were not seen. ...
Pinus mugo plays a significant ecological role in the natural environment at high altitudes in the mountains including the Alps, Pyrenees, Carpathians, and Balkans. In such severe conditions, it is subjected to the harmful effects of various abiotic and biotic factors. In one of the areas of its natural occurrence in Tatra Mts. (southern Poland), for the last few years, a significant intensification of needle disease has been observed. Symptoms similar to those recorded in Tatra Mts. also occur on other Pinus species in Europe and North America, where they are caused by fungi belonging to the genus Elytroderma, Lophodermella, Lophophacidium or Ploioderma (Rhytismataceae). The current paper presents the results of research which was mainly aimed at characterization of disease symptoms observed for the first time in Poland on P. mugo needles, and identification of the main causal agent with use of the morphological and molecular technique. Based on the analyses performed at different times of the year (2015–2020), it was found that dieback symptoms initially appeared only on first-year needles, a few weeks after their development. Symptoms occur on one or both needles in the bundle. The distal parts of the needles died, while the basal parts remained green. In the following year, mainly in June and July, on the previous year’s needles attached to the shoots, mature ascomata can be seen. The fungus Lophodermella sulcigena has been identified as the cause of these symptoms. So far, the related species L. conjuncta has not been found. The morphological features of the pathogen microstructure produced on P. mugo needles are presented. Attention was drawn to certain features that may make its identification difficult, especially in terms of shapes and sizes of ascospores. The phylogenetic position of the identified causal agent in relation to closely related other species was determined. The current results confirmed that L. sulcigena shows great phylogenetic similarity to L. montivaga, which is found in North America. Nine rDNA barcode sequences of L. sulcigena obtained in this work will enrich the NCBI GenBank database. The obtained results, indicating the presence of other fungi in L. sulcigena ascomata, which may limit the spread of its ascospores, were also discussed.
... The best-known snow molds on woody plants are the brown felt blight caused by Herpotrichia pinetorum and the white snow blight caused by Gremmenia infestans. Allantophomopsis cytisporea, previously considered a postharvest pathogen (black rot) of the cranberry (Vaccinium macrocarpum), has been identified in Switzerland on several occasions as a snow mold on various woody plant species in subalpine and alpine regions (Schneider et al., 2009;Sieber, 2019). The main host is common heather (Calluna vulgaris) in which the fungus is a common leaf endophyte (Petrini, 1985). ...
... At one location, it was responsible for all the alleged H. pinetorum symptoms on the dwarf mountain pine. Another location is suspected of being an evolutionary hot spot because two snow mold species that are closely related to A. cytisporea occurred together with A. cytisporea in the same sample: Pseudophacidium ledi and Phacidium lacerum (Sieber, 2019). Interestingly, A. cytisporea can switch from a harmless endophytic lifestyle during the vegetation period to a pathogenic lifestyle below the snow during winter, where it first kills leaves and whole shoots of common heather and then expands to adjacent vegetation, including shoots of conifers. ...
The global leaf surface of woody plants is estimated to be several times as big as the land area. This huge and diverse habitat is colonized by microorganisms whose number of individuals exceeds the number of stars in the universe many times over. Fungi make up a large part of the leaf colonizers. Fungi colonize both the leaf surfaces and the interior of the leaves. Most fungi that penetrate the leaves are harmless symbionts. They are called endophytes. Most tree-leaf endophytes form disjunct inter- and/or intracellular thalli in the leaf tissues. Endophyte communities are diverse. Their composition depends strongly on the host, climate, location, season, and age of the trees and leaves. They play an important role in the defense against pathogens and herbivores and also produce valuable pharmaceutical products (e.g., taxol). Many endophytes are closely related to pathogens but, unlike pathogens, are tolerated or “domesticated” by the host. The mechanism behind this mutual tolerance is still not known.
Forests form rich biodiversity hubs that act as large reservoirs of natural carbon. The spatial and temporal heterogeneity of these complex habitats of forest floors provides ecological services of immense socio-economic importance. However, these socio-economic ecological hotspots are incessantly exposed to multifarious abiotic, biotic, and anthropogenic disturbances, amongst which unpredictable forest pest (i.e., bark beetle) outbreak account for the loss of vegetation and microbiome of measurable quantum. The importance of the microbiome in forming an inseparable functional unit of every host and shaping its interaction with other partners has been well realized. Interestingly, forest pests, including bark beetles, are also reported to rely on their endosymbiotic microbial partners to manipulate tree defense machinery. In contrast, the microbiome forming the holobiont of trees also regulates the overall function and fitness of the host and significantly contributes to tackling these challenging situations. Nevertheless, how the holobiont of trees directly or indirectly influence beetle holobiont is still an enigma. The present review shall elaborate on the role of microbial tools in enhancing tree performance and fitness, which helps counter beetle damage. Besides, it shall also emphasize exploiting the role of microorganisms in acting as biocontrol agents in shielding the trees against beetle destruction. The application of endosymbiont-mediated RNA interference (RNAi) in working with two-tier specificity for controlling beetle devastations shall be discussed as new-age technological advances. All explanations are expected to put forth the potential of the microbial toolbox in offering better and more sustainable beetle management strategies in the future.
