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1.
Endophytic fungi occur on various types of leaf litter, but few studies have been done on their roles as saprophytes in decomposition. This study examined the succession of fungi in live, newly shed, and decomposing leaves at 2 months of decomposition of Camellia japonica and chemical changes in decomposing leaves colonized by endophytes. Coccomyces nipponicum, Lophodermium sp., Geniculosporium sp. 1, and Colletotrichum gloeosporioides were isolated from living leaves. Coccomyces nipponicum and Lophodermium sp. were also isolated frequently from newly shed and decomposing leaves. These two fungi caused a decrease of lignin content and bleaching in decomposing leaves under field and laboratory conditions. Total hyphal length in decomposing leaves was higher in bleached portions than in surrounding nonbleached portions, which probably reflected the early onset of hyphal growth of endophytes inside leaf tissue at leaf senescence or death. Incubation of newly shed leaves that were sterilized to exclude previously established endophytes resulted in no occurrence of bleached portions in decomposing leaves on the forest floor. This result indicated that these endophytes were incapable of colonizing leaves directly after litterfall and that the persistence of endophytes from live leaves was crucial for their colonization in decomposing leaves.  相似文献   

2.
The diversity, composition, and host recurrence of endophytic fungi in the Xylariaceae were compared in subtropical (ST), cool temperate (CT), and subboreal forests (SB) in Japan based on the 28S ribosomal DNA sequences from fungal isolates. A total of 610 isolates were obtained from the leaves of 167 tree species in three sites, which were classified into 42 operational taxonomic units (OTUs) at the 99 % similarity level of the 28S rDNA sequence. ST, CT, and SB yielded 31, 13, and three OTUs, respectively. The OTU richness, diversity, and evenness of fungal communities were in the order: ST > CT > SB. The 42 OTUs were assigned to nine genera in the Xylariaceae: Xylaria, Annulohypoxylon, Anthostomella, Biscogniauxia, Nemania, Hypoxylon, Muscodor, Daldinia, and Rosellinia. Xylarioid isolates in the subfamily Xylarioideae outnumbered Hypoxyloid isolates in the subfamily Hypoxyloideae in ST and CT, whereas the opposite was found in SB. Sørensen’s quotient of similarity was generally low between the three sites. Host recurrence of fungal OTUs was evaluated with the degree of specialization of interaction network between xylariaceous endophytes and plant species and compared between the three sites. We found that the networks in the three sites showed a significantly higher degree of specialization than simulated networks, where partners were associated randomly. Permutational multivariate analyses of variance indicated that plant family and leaf trait significantly affected the OTU composition in ST, which can account for the specialization of interaction network and host recurrence of xylariaceous endophytes.  相似文献   

3.
Dendrobium spp. are traditional Chinese medicinal plants, and the main effective ingredients (polysaccharides and alkaloids) have pharmacologic effects on gastritis infection, cancer, and anti-aging. Previously, we confirmed endophytic xylariaceous fungi as the dominant fungi in several Dendrobium species of tropical regions from China. In the present study, the diversity, taxonomy, and distribution of culturable endophytic xylariaceous fungi associated with seven medicinal species of Dendrobium (Orchidaceae) were investigated. Among the 961 endophytes newly isolated, 217 xylariaceous fungi (morphotaxa) were identified using morphological and molecular methods. The phylogenetic tree constructed using nuclear ribosomal internal transcribed spacer (ITS), large subunit of ribosomal DNA (LSU), and beta-tubulin sequences divided these anamorphic xylariaceous isolates into at least 18 operational taxonomic units (OTUs). The diversity of the endophytic xylariaceous fungi in these seven Dendrobium species was estimated using Shannon and evenness indices, with the results indicating that the dominant Xylariaceae taxa in each Dendrobium species were greatly different, though common xylariaceous fungi were found in several Dendrobium species. These findings implied that different host plants in the same habitats exhibit a preference and selectivity for their fungal partners. Using culture-dependent approaches, these xylariaceous isolates may be important sources for the future screening of new natural products and drug discovery.  相似文献   

4.
Decomposition processes of Camellia japonica leaf litter were investigated over an 18-month period with reference to the role of fungal succession in the decomposition of lignin and holocellulose. Decomposition and fungal succession were studied in bleached and nonbleached portions of litter, which were precolonized by ligninolytic and cellulolytic fungi, respectively. Coccomyces nipponicum and Lophodermium sp. (Rhytismataceae), which can attack lignin selectively, caused mass loss of lignin and were responsible for bleaching during the first 4 months (stage I), whereas cellulolytic fungi caused mass loss of holocellulose in adjacent nonbleached portions. Soluble carbohydrates and polyphenols also decreased rapidly during this stage. Pestalotiopsis guepini, coelomycete sp.1, and the Nigrospora state of Khuskia oryzae caused mass loss of holocellulose between 4 and 14 months (stage II) and Xylaria sp. caused mass loss of both lignin and holocellulose from 14–18 months (stage III). In stages II and III, decomposition was more rapid in bleached portions than in nonbleached portions probably due to the prior delignification of lignified holocellulose in bleached portions. Frequencies of these fungi showed different responses among species to the pattern of changes in lignin and holocellulose contents during decomposition. Total hyphal length increased in both portions over the study period, but mycelia of basidiomycetes accounted for about 2% of total hyphal length, suggesting that their role in fungal succession and decomposition was low. Lignin and nitrogen contents were consistently lower and holocellulose content was higher in bleached portions than in nonbleached portions during decomposition. The succession of ligninolytic and cellulolytic fungi was a major driving factor that promoted decomposition and precolonization by ligninolytic fungi enhanced decomposition.  相似文献   

5.
Endophytic fungi were isolated from leaves of Neolitsea sericea, a major lauraceous tree in the laurel forests of southern Kyushu, collected from the understory layer of broadleaf and conifer stands. Cytosphaera sp. and a species of Ascomycetes in leaf blade segments, plus a xylariaceous species and Phomopsis spp. in petiole segments, were isolated at relatively high frequency. In general, isolation frequencies of endophytes were higher in petiole than blade segments. In blade segments, patterns of endophyte isolation were quite different among stands, while relatively similar in petiole segments. Significant effects of sampling sites or canopy vegetation were rarely detected. the understory layer of laurel forests. Neolitsea sericea is an evergreen broadleaf lauraceous tree, widely distributed in areas of eastern Asia. In southern Kyushu, it is one of the most common trees, growing both as canopy and understory species. In this study, endophytes were isolated from the leaves of N. sericea growing in the understory layer of conifer and broadleaf forest stands to survey the endophytes of N. sericea leaves and to examine the effect of the canopy layer on endophytic mycobiota in understory plants.  相似文献   

6.
Fungi play a crucial role in the decomposition of lignin in fallen leaves but few studies have examined the functional roles of ligninolytic fungi associated with the decomposition of fallen leaves on tropical forest soils. This study examined fungal populations responsible for lignin decomposition in Castanopsis sieboldii leaves in a subtropical evergreen broad-leaved forest in southern Japan. Fallen leaves of C. sieboldii are characterized by the occurrence of bleached portions attributable to fungal colonization of leaf tissues and decomposition of lignin. The bleached area accounted for 29.7%, on average, of the total area of C. sieboldii fallen leaves in the study site. Leaf mass per unit area (LMA) and lignin content were lower in the bleached area than in the surrounding nonbleached area of the same leaves, indicating that removal of lignin enhanced mass loss from leaf tissues and created small-scale heterogeneity of decomposition within single leaves. An unidentified species of Lachnocladiaceae (Basidiomycetes) was isolated frequently from the bleached area and caused selective decomposition of lignin in leaves under pure culture conditions, indicating that this fungus was responsible for the bleaching. The greater hyphal length of basidiomycetes in the bleached area than in the nonbleached area supported the finding that this Lachnocladiaceae sp. was associated with the bleaching. The relatively rapid decomposition of C. sieboldii leaves on the subtropical forest soil is partly attributable to colonization of the litter by this Lachnocladiaceae sp.  相似文献   

7.
Fungal endophytes were isolated from the leaves of soybean cultivars in Brazil using two different isolation techniques — fragment plating and the innovative dilution-to-extinction culturing — to increase the species richness, frequency of isolates and diversity. A total of 241 morphospecies were obtained corresponding to 62 taxa that were identified by analysis of the internal transcribed spacer (ITS) of the ribosomal DNA (rDNA). The Phylum Ascomycota predominated, representing 99% and 95.2% of isolates in the Monsoy and Conquista cultivars, respectively, whereas the Phylum Basidiomycota represented 1% and 4.8% of isolates, respectively. The genera Ampelomyces, Annulohypoxylon, Guignardia, Leptospora, Magnaporthe, Ophiognomonia, Paraconiothyrium, Phaeosphaeriopsis, Rhodotorula, Sporobolomyces, and Xylaria for the first time were isolated from soybean; this suggests that soybean harbours novel and highly diverse fungi. The yeasts genera Rhodotorula and Sporobolomyces (subphylum Pucciniomycotina) represent the Phylum Basidiomycota. The species richness was greater when both isolation techniques were used. The diversity of fungal endophytes was similar in both cultivars when the same isolation technique was used except for Hill’s index, N1. The use of ITS region sequences allowed the isolates to be grouped according to Order, Class and Phylum. Ampelomyces, Chaetomium, and Phoma glomerata are endophytic species that may play potential roles in the biological control of soybean pathogens. This study is one of the first to apply extinction-culturing to isolate fungal endophytes in plant leaves, thus contributing to the development and improvement of this technique for future studies.  相似文献   

8.
Fungal symbioses with plants are ubiquitous, ancient, and vital to both ecosystem function and plant health. However, benefits to fungal symbionts are not well explored, especially in non‐mycorrhizal fungi. The Foraging Ascomycete hypothesis proposes that some wood‐decomposing fungi may shift life‐history strategies to endophytism to bridge gaps in time and space between suitable substrates. To test this hypothesis we examine spatial relationships of Xylaria endophytic fungi in the forest canopy with Xylaria decomposer fungi on the forest floor. We sampled for fungi of the genus Xylaria using a spatially explicit sampling scheme in a remote Ecuadorian cloud forest, and concurrently carried out an extensive culture‐based sampling of fungal foliar endophytes. We found 36 species of Xylaria in our 0.5 ha plot, 31 of which were found to only occur as fruiting bodies. All five species of Xylaria found as endophytes were also found as fruiting bodies. We also tested the relationships of both stages of these fungi to environmental variables. Decomposer fungi were differentiated by species‐specific habitat preferences, with three species being found closer to water than expected by chance. In contrast, endophytes displayed no sensitivity to environmental conditions, such as host, moisture, or canopy cover. We found evidence of spatial linkage between life stages in two species. We also demonstrate that direct transmission of endophytes from leaves to woody substrates is possible. These results indicate that endophytism may represent one way for decomposer fungi to escape moisture limitation, and that endophytic fungi may act as sources of dispersal for decomposer fungi consistent with predictions of the Foraging Ascomycete hypothesis.  相似文献   

9.
Fungi that selectively remove lignin cause extensive bleaching of leaf litter, which results in the acceleration of litter decomposition. The taxonomic diversity and host recurrence of saprotrophic fungi associated with bleached leaf litter were investigated in a subtropical forest in southern Japan. A total of 211 fungal isolates and sporocarps were obtained from bleached portions of leaf litter of 33 plant species in 18 families and were classified into 83 operational taxonomic units (OTUs) at the 97% similarity level of the ITS rDNA sequence. These fungal OTUs belonged to Rhytismataceae and Xylariaceae in the Ascomycota, and Marasmiaceae, Mycenaceae, Lachnocladiaceae, and Physalacriaceae in the Basidiomycota. OTUs in Rhytismataceae and Marasmiaceae showed a significantly higher degree of recurrence for plant species than simulated networks where partners were associated randomly. In contrast, OTUs in Xylariaceae and Mycenaceae showed no significant recurrence for plant species. Such differing degrees of recurrence for plant species implied different roles of fungal families in leaf litter decomposition.  相似文献   

10.
Sixty-nine endospore-forming bacterial endophytes consisting of 15 different species from five genera were isolated from leaves, pods, branches, and flower cushions of Theobroma cacao as potential biological control agents. Sixteen isolates had in vitro chitinase production. In antagonism studies against cacao pathogens, 42% inhibited Moniliophthora roreri, 33% inhibited Moniliophthora perniciosa, and 49% inhibited Phytophthora capsici. Twenty-five percent of isolates inhibited the growth of both Moniliophthora spp., while 22% of isolates inhibited the growth of all three pathogens. Isolates that were chitinolytic and tested negative on Bacillus cereus agar were tested with in planta studies. All 14 isolates colonized the phyllosphere and internal leaf tissue when introduced with Silwet L-77, regardless of the tissue of origin of the isolate. Eight isolates significantly inhibited P. capsici lesion formation (p = 0.05) in detached leaf assays when compared to untreated control leaves. ARISA with bacilli specific primers amplified 21 OTUs in field grown cacao leaves, while eubacteria specific primers amplified 58 OTUs. ARISA analysis of treated leaves demonstrated that inundative application of a single bacterial species did not cause a long-term shift of native bacterial communities. This research illustrates the presence of endospore-forming bacterial endophytes in cacao trees, their potential as antagonists of cacao pathogens, and that cacao harbors a range of bacterial endophytes.  相似文献   

11.
Fungal endophytes were isolated from leaves of Centella asiatica (Apiaceae) collected at Mangoro (middle eastern region of Madagascar, 200 km from Antananarivo). Forty- five different taxa were recovered. The overall foliar colonization rate was 78%. The most common endophytes were the non-sporulating species 1 (isolation frequency IF 19.2%) followed by Colletotrichum sp.1 (IF 13.2%), Guignardia sp. (IF 8.5%), Glomerella sp. (IF 7.7%), an unidentified ascomycete (IF 7.2%), the non-sporulating species 2 (IF 3.7%) and Phialophora sp. (IF 3.5%). Using sequences of the ribosomal DNA internal transcribed spacer (ITS) regions, major endophytes (IF > 7%) were identified as xylariaceous taxa or as Colletotrichum higginsianum, Guignardia mangiferae and Glomerella cingulata. Results from in vitro fungal disk experiments showed a strong inhibitory activity of the xylariaceous non-sporulating species 1 against G. mangiferae and C. higginsianum and of C. higginsianum against G. mangiferae. This can be explained by antagonism between dominant taxa.  相似文献   

12.
This study focused on the taxonomy and diversity of the endophytic fungi associated with Vellozia gigantea, an endemic, ancient, and endangered plant species that occurs only in the rupestrian grasslands of Brazil. A total of 285 fungal isolates were recovered from leaves and roots of the V. gigantea, which were identified in 27 genera and 87 different taxa using molecular taxonomy methods. Xylaria berteri, Diaporthe sp. 1, Nigrospora oryzae, Muscodor sp. 1, Colletotrichum aeschynomene, and Trichoderma viride occurred in the highest frequency in both the leaf and root. Diaporthe was the most abundant genus, with 70 endophytic isolates recovered from the leaves and roots. Among all the taxa identified, 62 occurred as singlets, including those of the genera Clonostachys, Coccomyces, Crucellisporiopsis, Daldinia, Myxotrichum, Pallidocercospora, Pezicula, Peyronellaea, and Pseudocercospora. The diversity indices displayed high values, showing that V. gigantea shelters a diverse and rich mycobiota. Our results indicate that V. gigantea shelters in its tissues a highly diverse and cryptic mycobiota, including several rare species previously unreported as endophytes, but that are reported to have different ecological functions, which might be an important biological component contributing to the fitness of the plants living in the rupestrian grassland.  相似文献   

13.
Communities of endophytic fungi in leaves of Manna ash (Fraxinus ornus) were examined to both the north and south of the Alps, i.e. within and beyond the native range of this tree species. Almost all leaves examined had been colonized by endophytic fungi. One hundred and two morphotypes were found, and 62 of them were identified to genus or species level using ITS sequencing and micromorphology. Venturia orni was most frequent and occurred in almost one third (32%) of the 1536 examined leaf segments. It was five times more abundant than Colletotrichum acutatum, the second most frequent endophyte. Other frequently isolated endophytes include Paraconiothyrium sp. 1, Mycosphaerella aurantia, Septoria cretae, Botryosphaeria dothidea and Boeremia exigua. The ash dieback pathogen was not isolated. The endophyte communities differed between the north and south of the Alps and the individual tree types had a distinct influence within sites.  相似文献   

14.
This study was conducted to explore fungal endophyte communities inhabiting a toxic weed (Stellera chamaejasme L.) from meadows of northwestern China. The effects of plant tissue and growth stage on endophyte assemblages were characterized. Endophytes were recovered from 50 % of the samples, with a total of 714 isolates. 41 operational taxonomical units (OTUs) were identified, consisting of 40 OTUs belonging primarily to Ascomycota and 1 OTU belonging to Basidiomycota. Pleosporales and Hypocreales were the orders contributing the most species to the endophytic assemblages. The total colonization frequency and species richness of endophytic fungi were higher in roots than in leaves and stems. In addition, for the plant tissues, the structure of fungal communities differed significantly by growth stages of leaf emergence and dormancy; for the plant growth stages, the structure of fungal communities differed significantly by plant tissues. This study demonstrates that S. chamaejasme serves as a reservoir for a wide variety of fungal endophytes that can be isolated from various plant tissues.  相似文献   

15.
Leaf-inhabiting endophytic fungi of Fraxinus excelsior growing in a floodplain forest were isolated during 2008 to investigate vertical community structure, species richness and seasonal variation. The analysis of 848 fungal endophytes from 213 leaves resulted in 50 different species. In the understorey, infection density and species richness were higher than in the crowns of mature trees throughout the whole vegetation period. Within tree crowns, sun-exposed leaves of the top canopy exhibited the lowest infection rates. Most species were rare or absent in spring and in the light crowns and frequent in autumn and the understorey. However, some species, especially the two most frequent, Alternaria infectoria and A. alternata, deviated from these patterns. Young leaves were nearly free of endophytes. Apparently, the subsequent infection and establishment of fungi strongly depend on microclimatic parameters and leaf characters, which create highly variable spatial and temporal colonisation patterns within an individual tree.  相似文献   

16.
Endophytes may gradually accumulate in the new geographic range of a non-native plant, just as pathogens do. To test this hypothesis, the dynamics of colonization and diversity of foliar fungal endophytes of non-native Ageratina adenophora were investigated. Previous reports showed that the time since the initial introduction (1930s) of A. adenophora into China varied among populations. Endophytes were sampled in three provinces of Southwest China in 21 sites that varied from 20 to 70 years since the introduction of A. adenophora from its native Central America. Endophyte isolation frequencies varied from 1.87 % to 60.23 % overall in a total of 4,032 leaf fragments. Based on ITS sequence variations, 463 fungal endophytes were distinguished as 112 operational taxonomic units (OTUs) belonging to the Sordariomycetes (77 OTUs, 373 isolates), Dothideomycetes (18 OTUs, 38 isolates), and Agaricomycetes (17 OTUs, 52 strains) classes. Colletotrichum (28.51 %), Nemania (14.90 %), Phomopsis (13.17 %), and Xylaria (4.97 %) were the most abundant genera. Both endophyte diversity and overall isolation frequency increased with time since introduction. The genetic differentiation of the fungus Colletotrichum gloeosporioides indicated that the dispersal of endophytes was likely affected by a combination of geographic factors and the invasion history of the host A. adenophora.  相似文献   

17.
王欣禹  周勇  任安芝  高玉葆 《生态学报》2014,34(23):6789-6796
以感染内生真菌的天然禾草羊草为实验材料,通过体外纯培养条件下的内生真菌、感染内生真菌的离体叶片和在体叶片对3种病原菌的抑菌实验,以探讨内生真菌对宿主植物羊草在抗病性方面的贡献。结果表明:体外纯培养条件下,分离自羊草的内生真菌Epichlobromicola对新月弯孢(Curvularia lunata)、根腐离蠕孢(Bipolaris sorokiniana)和枝孢霉(Cladosporium sp.)这3种病原菌都具有抑制作用,抑菌率分别达56.22%,46.93%和45.15%,且内生真菌培养滤液可以有效抑制这3种病原菌的孢子萌发,平均萌发率分别为30.4%,15.7%和16.4%;宿主植物叶片在离体条件下,内生真菌感染可以有效降低羊草叶片受C.lunata和C.sp.侵染后的病斑数或病斑长度,但对B.sorokiniana不起作用,甚至提高了叶片的病斑数及病斑长度,而离体叶片提取液对不同病原菌均有不同程度的抑制作用;在体条件下,内生真菌均可以通过降低叶片病斑数来增强羊草植株对这3种病原菌的抗性。由此看来,内生真菌E.bromicola对宿主植物羊草在抗病原菌侵染方面有一定的增益作用。  相似文献   

18.
Phyllosphere fungi on living and decomposing leaves of giant dogwood   总被引:3,自引:0,他引:3  
Phyllosphere fungi on living leaves and their succession on decomposing leaves were studied on giant dogwood (Swida controversa). A total of 12 and 34 fungal species were isolated from the interior and surface, respectively, of living leaves, and 15 frequent species were considered as phyllosphere fungi. Six of these 15 species were also frequent on decomposing litter. Characteristic successional trends were observed in the 6 phyllosphere fungi during decomposition. The sum of frequencies of endophytes decreased as decomposition progressed, and no endophytes were isolated from the litter at the 11th month of decomposition. The sum of frequencies of epiphytes increased as decomposition progressed. Endophytes and epiphytes showed different responses to litter mass loss and concentrations of nitrogen, lignin, and total carbohydrates during the decomposition process. These results suggested that epiphytes may survive on decomposing leaves as primary decomposers on the ground, thereby excluding endophytes by competition for available energy sources, and that epiphytes may have a greater contribution to decomposition than endophytes in dogwood leaves.  相似文献   

19.
A systematic study was made of the endophytes of Azadirachta indica A. Juss (the neem tree) growing in several of its natural habitats in India. A total of 233 isolates of endophytic fungi representing 18 fungal taxa were obtained from segments of bark, stem, and leaves of this tree. Hyphomycetes (62.2%) were the most prevalent followed by the Coelomycetes (27.4%) and Mycelia Sterilia (7.7%). As mathematically determined, the maximum species richness and frequency of colonization of endophytes appeared in leaf segments rather than stem and bark tissues from each location. Endophytic colonization frequency was also greater in leaves (45.5%) than bark (31.5%). The leaf samples from all locations were nearly constant in their endophytic composition, whereas bark samples showed maximum diversity at different locations. Inter-site comparisons for endophytic diversity, however, were not significantly different with Loc1 and Loc2 having a maximum of 66.67% J c. The smallest similarity was between Loc2 and Loc3 of 54.17% J c. The dominant endophytic fungi isolated were Phomopsis oblonga, Cladosporium cladosporioides, Pestalotiopsis sp., Trichoderma sp, and Aspergillus sp. Genera such as Periconia, Stenella, and Drechslera are reported here for the first time as endophytes from this host plant. This report illustrates the value of sampling different tissues of a given plant in several locations to obtain the greatest species diversity of endophytes. The rich and sizeable collection of endophytic fungi from this specific plant may represent a unique source of one or more of the interesting and useful bioactive compounds normally associated with A. indica such as the azadirachtins and related tetranortriterpenoids.  相似文献   

20.
We surveyed the fungal endophytes in the leaves and roots of Phragmites australis plants along a gradient of reed decline at Lake Trasimeno (central Italy) in Oct. 2010. An integrated approach consisting of cultivation and molecular identification was used. Endophytes were recovered from 61.59 % of the samples, with a total of 1 541 isolates. On the basis of a molecular analysis of the rDNA Internal Transcribed Spacer (ITS) region, 25 operational taxonomic units (OTUs) were identified. Fusarium sp. (OTU 21) and Gibberella moniliformis (OTU 1) were the most frequently isolated fungi. Comparisons of the leaf and root samples demonstrated spatial heterogeneity in the endophyte assemblages among the plant parts and sites. In this study, we have shown that reed plants in different states of decline harbour different endophytic communities. This finding may help to understand the very complex scenario of reed die-back.  相似文献   

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