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1.
The main objective of this study was to obtain more comprehensive knowledge about the effect of water stress on endophytic fungal communities in asymptomatic and declining cork oak trees. Six asymptomatic and six declining cork oak trees were randomly selected in a natural cork oak forest located in Sardinia, Italy. In February 2003, the soil around three asymptomatic and three declining trees was covered with a circular plastic film to reduce rain water supply with the intention to induce water stress. The remaining six trees served as controls. Predawn xylematic water potential (PWP) was used as water status indicator and measured seasonally. Between July 2003 and June 2004, fungal endophytes were isolated every 2–4 months from twigs, branches and woody tissues. Significant differences in PWP between covered and control trees were detected mainly in autumn. Gas exchange was greatest in asymptomatic control plants. All tissues were colonized by endophytic fungi. Nineteen fungal species were isolated from 1620 plant fragments. Biscogniauxia mediterranea was the most frequently isolated fungus. Its isolation frequency was significantly higher in declining covered trees than in control trees (p < 0.05). Presence of this fungus in asymptomatic control trees was significantly higher in winter than in summer. Water stress seems to reduce species diversity of the endophytic mycobiota in cork oak and to promote proliferation of some potentially pathogenic endophytes. 相似文献
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Fungal endophytes are an important part of the plant microbiome and participate in maintaining the stability of ecosystems. Culture‐based methods are frequently considered in studying fungal communities because of their advantages in providing cultures for further experiments and their low cost. In comparison with next‐generation sequencing methods, their ability to assess fungal diversity is questionable. Here, we show how using two different incubation temperatures can improve the yield of fungal endophytes by culture‐based methods. Diversity, organ preference and spatiotemporal variability of endophytic fungal communities living within Quercus brantii L. were investigated using two different incubation temperatures. To test the effects of using low‐temperature incubation on diversity estimations, twigs and leaves of Quercus brantii were incubated under 25°C and 4°C conditions. Isolation rate and Hill's series of diversity were calculated for each sample. Model‐based analysis was used to evaluate the effects of (a) incubation temperature, (b) organ type and (c) spatiotemporal variations on fungal isolation rate, fungal diversity and community composition. Our results showed a strong organ specificity and temporal dynamics among endophytic fungal communities, but the location of the forest stand had only a limited effect on fungal community composition. Low‐temperature incubation enabled us to improve culture‐based methods by discovering the diversity of cold‐adapted fungal endophytes and a significantly different part of the endophytic communities that is usually missed by customary culturing temperature. The isolation of cold‐adapted endophytes from a semiarid environment opens a new window to further studies on this kind of fungi in such ecosystems. 相似文献
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Endohyphal bacteria from fungal endophytes of the Mediterranean cypress (Cupressus sempervirens) exhibit in vitro bioactivity 
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下载免费PDF全文 Endohyphal organisms of endophytic fungi can induce, or promote, beneficial effects of their respective host fungi to the host plant that harbours them. The Cupressaceae plant family (Coniferales) hosts highly bioactive endophytic fungi. Here, we show that a fraction of such endophytic fungi harbours bioactive endohyphal bacteria with a non‐obligatory symbiotic lifestyle. Indeed, 5 of 16 (31.25%) endophytic fungi of Cupressus sempervirens harboured endofungal bacterial strains of Bacillaceae (G+, Bacilli) and Sphingomonadaceae (G?, α‐Proteobacteria), that is Bacillus pumilus (from the fungi Leptosphaeria CSE211 and Pyrenochaeta CSE134), Bacillus subtilis (from the fungi Leptosphaeria CSE212 and Ascorhizoctonia CSE148) and Sphingomonas paucimobilis (from the fungus Ascorhizoctonia CSE195). Notably, each endophytic fungal species contained only one endofungal bacterial species that was stably maintained in symbiosis over several rounds of subculturing. Moreover, we investigated whether cypress endofungal bacteria (CEB) could benefit their host fungus competing with other fungi and bacteria or the host plant against the invading microorganisms. In vitro assays indicated that CEB possessed antagonistic activity against cypress endophytic and pathogenic microbiome. Also, CEB metabolites and volatile compounds (VOCs) exhibited antifungal and antibacterial activity against the target microbiome. Bioactivity of CEB was less than that of the endophytic microbiome of Cupressaceae, on which we reported earlier. In conclusion, our work is the first to document endohyphal bacteria of fungal endophytes of C. sempervirens and the bioactivity of such endohyphal symbionts. These findings implicate a complicated interrelationship among host plant, endophytic microbiome and endofungal bacteria, which might be of high importance for evolutionary, as well as environmental and agricultural studies. Eventually, endohyphal bacteria may be introduced as a novel source for lead molecule discovery. 相似文献
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Leaves of Japanese beech (Fagus crenata) were collected monthly during the vegetation period at five sites in the Tohoku district in Japan to isolate endophytic fungi. Leaves were also collected only once at two additional sites. Two endophytic fungi were dominant, a Discula species and a sterile mycelium. This result strongly suggests that these two fungi are generally associated with leaves of the Japanese beech at different sites. At most sites the isolation frequency of Discula sp. was greatest in June and gradually decreased from July to October whereas the isolation frequency of the sterile mycelium increased during the vegetation period and remained at a high isolation frequency in October. Spores of Discula sp. were released for a very short time in late May, just after the disappearance of the snow cover on the forest floor. These spores may be important for the infection of newly sprouting leaves. 相似文献
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In recent years, a considerable number of studies have harnessed the power of genomics to decipher the role of pathogenesis‐related (PR) proteins in plant defence against various biotic and abiotic stresses. Chitinases are PR antifungal proteins expressed constitutively at low levels in plants and induced during biotic pressures and are demonstrated to be involved in the plant defence responses. Remarkable induction of chitinase enzymes by various abiotic agents (salicylic acid, jasmonic acid, ethylene and ozone) and biotic components (pathogens, insect pest, fungal cell wall components and oligosaccharides) is well demonstrated in plants. Several reviews on plant chitinase expression during host–pathogen interaction are available for annual species, whilst reports of their expression in tree species are limited to a few woody perennials: Populus, Pinus, Picea, Eucalyptus, Castanea and Pseudotsuga. The aim of this paper is to review the induction of chitinase during various stresses and developmental processes in forest tree species. 相似文献
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Etiologic of shoot dicback of young larches in the subalpine zone. I, Studies to possibles fungi-infections . Infection experiments with Ascocalyx laricina (Ettlinger) Schläpfer-Bernhard and research on endophytic fungi of old and young larch trees showed that infection by this particular fungus can be ruled out as the cause of shoot dieback. 相似文献
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The species composition of the endophytic mycobiota in leaves of Japanese beech trees (Fagus crenata) and the sources for leaf infections were studied in a forest reserve situated in central eastern Honshu, Japan. To clarify the mechanism of infection of leaves, half of the branches were covered with polyethylene bags and species composition and levels of endophytic fungal infection were then compared with those of unbagged controls. Isolations were carried out from the leaves, petioles, and current‐year twigs of both, bagged and unbagged branches. Additionally, species composition was detected in overwintered terminal buds of beech trees and in the leaves of potted seedlings that had been placed in the field in different seasons. The species assemblage of the unbagged leaves, petioles, and current‐year twigs was dominated by Mycosphaerella buna, Ascochyta fagi, Periconiella sp., and Tritirachium sp. Other frequently recovered species were Xylaria sp., Phomopsis sp., and Tubakia dryina. Mycosphaerella buna and A. fagi were never isolated from leaves on bagged branches. A. fagi was, however, detected on both bagged and unbagged petioles and current‐year twigs at comparatively low isolation frequencies. The detection of Periconiella sp. on all occasions in both bagged and unbagged leaves was a characteristic feature that differs from those of the other three dominant endophytic fungi. The fungus was also detected without significant differences in bagged and unbagged petioles and current‐year twigs on most sampling dates. Furthermore, Periconiella sp. was isolated from immature twigs inside the bud scales. Tritirachium sp. was frequently detected in unbagged leaves and petioles and in both bagged and unbagged current‐year twigs, and rarely in bagged leaves and petioles, but was never recovered from terminal buds. The results of the potted seedling experiments revealed that all four dominant species had airborne inocula. The infection of leaves by M. buna occurs exclusively by airborne propagules, i.e. ascospores in spring and conidia in autumn. In Periconiella sp. hyphal growth of the fungus from immature twigs inside the buds into the leaf tissues was suggested in addition to infection by airborne inocula. Tritirachium sp. hyphae were suggested to grow from previous‐ to current‐year twigs. Ascochyta fagi was present in the outermost scales of overwintered terminal buds, but no systemic growth of the fungus into the petioles and current‐year twigs was observed. Our technique of covering the branches before new leaves unfolded was effective in preventing infection by airborne inocula of endophytic fungi. 相似文献
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Ophiostomatoid fungi are carried by various bark beetles. However, very little is known about the role of these fungi in conifer roots. We studied ophiostomatoid fungi in roots of dying and dead Pinus sylvestris trees and tested the potential phytotoxicity of some isolates using a sensitive bioassay with Lepidium sativum in Poland. Fungi were identified based on their morphology and DNA sequencing. Three ophiostomatoid fungi, Leptographium procerum, Sporothrix inflata and Ophiostoma pallidulum, were isolated from the roots. The most abundant soil‐borne fungus, S. inflata, and relatively rare O. pallidulum were isolated for the first time from roots of dying and dead pine trees. The frequency of S. inflata and O. pallidulum correlated with tree decline. The fungi were isolated more frequently from roots of dead than dying trees. Sporothrix inflata and O. pallidulum slightly reduced the stem and root growth of L. sativum. Leptographium procerum reduced more significantly root than stem growth. This species reduced root elongation 32–54% after 10–17 days of incubation. 相似文献
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Hakimeh Ziaie Juybari Mohammad Ali Tajick Ghanbary Heshmatollah Rahimian Kaivan Karimi Mahdi Arzanlou 《Forest Pathology》2019,49(6)
A total of 4,009 endophytic fungal isolates were recovered from healthy leaves, bark and xylem of Citrus sinensis in different seasons and age‐classes. Corresponding to those factors, the majorities of fungal isolates were recovered from leaves, 2‐yr‐old trees and winter, respectively. Fungal isolates were initially categorized based on cultural and morphological characters, and representatives of each morphotype were subjected to molecular identifications based on ITS‐rDNA and β‐tubulin sequences. All isolates obtained in this study belonged to the phyla Ascomycota and Basidiomycota assigned to 30 fungal taxa. The most abundant fungal species were Alternaria spp. Species diversity indices of Margalef richness and Shannon–Wiener revealed a high diversity of fungal taxa recovered from leaf and during winter. Frequency (%) of fungal endophytes was highest in winter followed by summer, autumn, and spring significantly, whereas the corresponding sequence was winter, autumn, summer and spring for the diversity of endophytic fungi. Overall, the results of this study based on the community and diversity of endophytic fungal species in C. sinensis showed that the type of plant tissue, season of sampling and age of tree play a driving role on their abundance while their diversity was mainly dependent on the type of plant tissue, season of sampling than on the age of tree. 相似文献
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The aim of this study was to describe endophytic fungal communities residing in five mangrove species (Sonneratia caseolaris, Sonneratia hainanensis, Sonneratia ovata, Sonneratia Paracaseolaris, Sonneratia apetala) collected at the south coast of China. The colonization frequency (CF) of endophytes in roots, stems and leaves was measured and the structures of endophytic communities were investigated, using endophytic fungal diversity indices and similarity coefficients. We found high biodiversity and tissue specificity of endophytic fungi. A total of 391 fungal isolates were identified using morphological and molecular methods. We recovered a total of 39 distinct endophytic species, of which Cytospora, Diaporthe, Fusarium, Glomerella, Mycosphaerella, Phoma, Phomopsis and Stemphylium were the dominant fungal taxa. Most recovered species were found on more than one host species but the dominant species differed according to host and tissue type. 相似文献
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Immunodepletion of α‐plurivorin effector leads to loss of virulence of Phytophthora plurivora towards Fagus sylvatica 下载免费PDF全文
下载免费PDF全文 R. J. D. Dalio F. Fleischmann A. Chambery R. Eichmann N. S. Massola Jr S. F. Pascholati W. Osswald 《Forest Pathology》2017,47(5)
Phytophthora species secrete several proteins during their interaction with plants. Some of these proteins manipulate host metabolism favouring infection, while others can be recognized by plants thus triggering defence. Elicitins are known to elicit plant defences, leading to resistance. Here, we characterized the elicitin α‐plurivorin and proved that it was essential for the virulence of Phytophthora plurivora towards Fagus sylvatica. The immunodepletion of this peptide impaired its penetration into host tissue and in parallel P. plurivora lost its ability to colonize beech roots. Furthermore, the lack of α‐plurivorin inside the host led to an up‐regulation of several defence‐related genes of both salicylic acid and jasmonate/ethylene pathways, suggesting that α‐plurivorin might act as an effector‐triggered susceptibility during infection. Consequently, plants survived infection with P. plurivora after α‐plurivorin immunodepletion, whereas the majority of the infected control plants had died at the end of the experiment. Because canonical elicitins are ubiquitously secreted by many Phytophthora species, it is possible that these molecules may play a similar role in other susceptible interactions, being a potential target for controlling Phytophthora diseases. 相似文献
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Characterization of Cylindrocarpon‐like species associated with litter in the old‐growth beech forests of Central Europe 下载免费PDF全文
下载免费PDF全文 R. Jankowiak H. Stępniewska J. Szwagrzyk P. Bilański G. Gratzer 《Forest Pathology》2016,46(6):582-594
Cylindrocarpon‐like fungi are globally distributed plant pathogens and have a wide range of host species. However, very little is known about the species that live in the topsoil of forests and their potential role in reducing the natural regeneration of tree species, particularly of forest trees that produce abundant fruit only once every few years. To enhance our understanding of the species that inhabit the topsoil, we studied the diversity and pathogenicity of Cylindrocarpon‐like fungi inhabiting the litter in old‐growth mixed‐beech forests in the Carpathians (Poland) and in the Alps (Austria), and in a managed beech stand in the Krakowsko‐Cz?stochowska Highland (Poland). The fungi inhabiting the beech litter were investigated using beechnuts and pine seedlings as bait. Isolates were identified based on morphology and DNA sequencing. The pathogenicity of the most common species was investigated by inoculating beech germinants. A wide range of Cylindrocarpon‐like fungi were associated with the beech litter: 718 cultures representing 12 species were isolated. Five taxa were identified down to species level: namely Ilyonectria crassa, I. pseudodestructans, I. rufa, Neonectria candida and N. obtusispora, and seven species were identified to genus level (Neonectria or Ilyonectria species). Ilyonectria destructans, which is considered to be the sexual morph of ‘Cylindrocarpon destructans’, was not found. There were qualitative and quantitative differences between the different forest sites in terms of Neonectria and Ilyonectria species composition in beech litter. The isolation frequency and species richness of Cylindrocarpon‐like fungi were greatest in beech litter taken from old‐growth mixed‐beech forests. Neonectria and Ilyonectria species were capable of killing beech germinants, suggesting that they may play a negative role in natural beech regeneration. 相似文献
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The mountain pine beetle (MPB), the most serious pest of lodgepole pine in mountainous western Canada, spread northeastward into lodgepole × jack pine hybrids in the boreal forest of Alberta in 2006. The MPB vectors three species of blue‐stain fungi, which contribute to the success of the beetles. These fungi were isolated from MPB larvae and galleries in several lodgepole × jack pine stands in the Grande Prairie region of northwestern Alberta in autumn 2006 and winter and spring 2007. Fungi were recovered from more than 95% of gallery systems. The three fungi were similarly prevalent but Ophiostoma montium was the most frequently isolated fungus at each sampling point, isolated from 72% to 90% of gallery systems compared with 63% to 78% for Grosmannia clavigera, and 61% to 86% for Leptographium longiclavatum. Ophiostoma montium and G. clavigera were isolated from more larvae than gallery samples, with the opposite true for L. longiclavatum. Most gallery systems contained multiple fungi with three fungi per gallery system being more common in autumn and winter and two fungi more common in the spring. The combination of G. clavigera and L. longiclavatum was less common among gallery systems with two fungi than either of the pairwise combinations containing O. montium. Fungal prevalence was the same above and below snow level. The prevalence of the three fungi did not differ significantly among stands sampled in the spring but stands with more G. clavigera tended to have less L. longiclavatum. The winter of 2006–2007 was colder than average throughout Alberta with temperatures below ?30°C in November, January and February, and all three fungi were present after the cold winter while most larvae had died, suggesting that overwintering mortality of the fungi will not limit persistence and spread of MPB in the boreal forest. 相似文献
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Trang T. Tran Morag Glen Chris Beadle David Ratkowsky Caroline Mohammed 《Forest Pathology》2019,49(2)
Acacia hybrid (Acacia mangium × Acacia auriculiformis) clones are widely planted in Vietnam with a total of approximately 400,000 ha to meet the demand for pulpwood, sawn timber and wood chip exports. Silvicultural techniques such as pruning and thinning have been applied to improve productivity and sawlog quality of Acacia hybrid plantations. However, those techniques may also create opportunities for wood decay fungi to enter the Acacia hybrid stems through wounds and cause stem defects that reduce sawlog quality and the value of the plantation. The presence of fungal decay agents in Acacia hybrid trees was examined in two Vietnamese plantations. In July 2011, just prior to a second thinning, discoloured wood samples were taken from a three‐year‐old Acacia hybrid plantation at Phan Truong Hai for the isolation of fungi. In July 2012, approximately 18 months after pruning and thinning treatments, discoloured wood samples were taken from a three‐year‐old Acacia hybrid plantation at Nghia Trung for the isolation of fungi. DNA sequencing of the rDNA ITS identified the isolates. In May 2015, approximately 4 years after thinning and fertilizer treatments, discoloured and decayed wood samples were taken from the above (7‐year‐old) Acacia hybrid plantation at Phan Truong Hai for fungal identification. DNA was extracted directly from discoloured and decayed wood samples and fungal rDNA ITS amplicons sequenced on a Roche 454 sequencer. The results showed that silvicultural treatments did not affect the fungal communities associated with discoloured and decayed wood of Acacia hybrid plantation at Phan Truong Hai. A total of 135 fungal species or OTUs (operational taxonomic units) were identified, including 82 members of Ascomycota and 52 Basidiomycota. 相似文献
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Differences in elm susceptibility against Ophiostoma novo‐ulmi have been related with differences in timing and degree of the tree defence responses. In this study, we used Fourier transform‐infrared spectroscopy, coupled with chemometric methods, to detect progressive changes in the metabolic profile of Ulmus minor and U. minor × U. pumila xylem tissues after inoculation with O. novo‐ulmi. Differences between control and inoculated trees were detected at 30 and 60 days post‐inoculation (dpi) in U. minor, and at 15, 30 and 60 dpi in U. minor × U. pumila. These differences were related with increased levels of lignin in the xylem tissues, suggesting an earlier defence response to the infection in the hybrids. 相似文献
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We isolated endophytic fungi from living healthy leaves, petioles, and current-year twigs of Ginkgo biloba L. from April to November 2004 with the objective of identifying the dominant endophytic fungal taxa, and monitoring their
occurrence and frequency. A total of 9 fungal taxa were identified to the genus level. Diversity measures inferred from the
Shannon–Wiener, Morisita–Horn, and S?rensen indices indicated that leaves and petioles harbored more diverse endophytic fungal
assemblages than twigs, and that fungal taxa involved in twigs shared less with those in leaves and petioles. Among the organs,
the occurrence pattern of overall endophytic fungi differed significantly, and two taxa, Phomopsis sp. and Phyllosticta sp., were the most frequently isolated and thus regarded as the dominant endophytic fungi. Phomopsis sp. was isolated frequently from twigs (84.8%) but rather few from leaves (16.1%) and petioles (24.3%). Phyllosticta sp. was isolated frequently from leaves (72.9%) and petioles (65.7%) but was never isolated from twigs. Temporal changes
in relative frequency of total endophytic fungi tended to differ among sampling dates for all three organs. The occurrence
of Phyllosticta sp. in both leaves and petioles was first detected in August and peaked in October. Phomopsis sp. was detected in twigs throughout the growing season. These results suggest that the distribution of the two dominant
endophytic fungi was organ-specific and differed within seasons. 相似文献
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The formation of reaction and barrier zones was studied in the xylem of Eucalyptus globulus and Eucalyptus nitens tree stems after wounding and artificial inoculation with two white rot fungi. The study had two objectives: to describe host responses in Eucalyptus spp. by light microscopy and to determine whether they would differ in a fungal treatment (wounding and inoculation by one of two fungal isolates) when compared to a control treatment (wounding only). Eucalyptus globulus and E. nitens developed similar reaction and barrier zones. The E. globulus barrier zone was characterized by kino vein formation. In both hosts, the reaction zone was primarily influenced by content and distribution of living tracheids and parenchyma cells within the sapwood. By contrast, the anatomy of the barrier zone showed similarities to the basic xylem structure of each host, except for some cell types that were newly formed (sclereids, kino veins) or increased in number (parenchyma cells, tracheids). Other cell types were reduced in number or completely absent. Host response in terms of barrier zone width appeared to be greater in the fungal than control treatment. Both wood decay fungi appeared to induce a wider barrier zone in both species than that associated with non‐specific damage caused exclusively by wounding. However, the small number of replicates available for this study was possibly insufficient to provide statistical evidence for different barrier zone width between fungal and control treatments. 相似文献