Re-epitypification of Neofusicoccum laricinum.

The lectotype and epitype of Neofusicoccum laricinum proposed in previous studies failed to meet the requirements of the International Code of Nomenclature for Algae, Fungi, and Plants. Here, we propose a valid lectotype and epitype for this species that meet the requirements of the Code.

New species Pythium amaminum sp. nov. isolated from river water on Amami Island in Japan.

Pythium amaminum sp. nov. was isolated from river and reservoir water on Amami island, Kagoshima Prefecture, Japan. The species can grow at temperatures between 10 °C and 35 °C. At the optimum temperature of 25 °C, the radial growth rate is 22.5 mm per day. Pythium amaminum produces filamentous sporangia consisting of branched, lobulate or digitate elements forming large complexes. Zoospores form inside the vesicle, which is discharged through a long tube at least 320 µm. Globose oogonia are ornamented with conical blunt spines. Oospores are aplerotic and globose. Antheridia twine around the oogonia or stick to them. These features having a both of the long discharge tube from sporangium and oogonia with spines are not observed in any other species of the genus Pythium, and thus we conclude that P. amaminum is a new Pythium species.

Keratin subsidies promote feather decomposition via an increase in keratin-consuming arthropods and microorganisms in bird breeding colonies.

Resource subsidies are well known to increase population densities of consumers. The decomposition process of these subsidised resources can be influenced by increasing consumer abundance. However, few studies have assessed whether resource subsidies can promote resource decomposition via a population increase in consumers. Here, we examined the effects of keratin subsidies on feather decomposition in egret and heron breeding colonies. Egrets and herons (Ardeidae) frequently breed in inland forests and provide large amounts of keratin materials to the forest floor in the form of feathers of chicks (that die). We compared the decrease in the weights of egret and heron feathers (experimentally placed on the forest floor) over a 12-month period among egret/heron breeding colonies (five sites) and areas outside of colonies (five sites) in central Japan. Of the feathers placed experimentally on forest floors, 92-97 % and 99-100 % in colonies and 47-50 % and 71-90 % in non-colony areas were decomposed after 4 and 12 months, respectively. Then, decomposition rates of feathers were faster in colonies than in areas outside of colonies, suggesting that keratin subsidies can promote feather decomposition in colonies. Field observations and laboratory experiments indicated that keratin-feeding arthropods and keratinophilic fungi played important roles in feather decomposition. Therefore, scavenging arthropods and keratinophilic fungi, which dramatically increased in egret and heron breeding colonies, could accelerate the decomposition of feathers supplied to the forest floor of colonies.

Comparison of Sapwood Discoloration in Fagaceae Trees After Inoculation with Isolates of Raffaelea quercivora, Cause of Mass Mortality of Japanese Oak Trees.

The mass mortality of oak trees has been prevalent in Japan since the late 1980s. The fungus Raffaelea quercivora is transmitted by an ambrosia beetle, Platypus quercivorus, which causes mortality. The beetle is able to bore galleries into the sapwood of most Fagaceae trees in Japan; however, the level of mortality caused by R. quercivora and P. quercivorus differs greatly among tree species. Previous studies by our research group have demonstrated that the virulence of R. quercivora differs among isolates when inoculated into Quercus serrata logs. However, interactions between the virulence of R. quercivora isolates and the susceptibility of other fagaceous species have yet to be elucidated. In this study, we inoculated the fresh logs of 11 fagaceous species with isolates of low and high virulence, and measured the tangential widths of discolored sapwoods 3 weeks after inoculation. Although the discoloration widths of Q. crispula sapwood were similar among all isolates, those of Q. serrata and Q. acutissima tended to increase with the more virulent isolates. Sapwood discoloration in Q. glauca, Q. acuta, Q. salicina, Lethocarpus edulis, and Castanopsis sieboldii was greatly increased by highly virulent isolates. Discoloration in Fagus japonica was not influenced by any of the isolates. The logs of Q. crispula and Q. serrata but not Q. glauca were significantly more discolored by a low-virulence isolate compared with standing trees. The various virulent isolates induced unique sapwood discoloration characteristics in each species, which may explain species-specific differences in mortality rates.

Distribution and evolution of glycoside hydrolase family 45 cellulases in nematodes and fungi.

BACKGROUND: Horizontal gene transfer (HGT) has been suggested as the mechanism by which various plant parasitic nematode species have obtained genes important in parasitism. In particular, cellulase genes have been acquired by plant parasitic nematodes that allow them to digest plant cell walls. Unlike the typical glycoside hydrolase (GH) family 5 cellulase genes which are found in several nematode species from the order Tylenchida, members of the GH45 cellulase have only been identified in a cluster including the families Parasitaphelenchidae (with the pinewood nematode Bursaphelenchus xylophilus) and Aphelenchoididae, and their origins remain unknown. RESULTS: In order to investigate the distribution and evolution of GH45 cellulase genes in nematodes and fungi we performed a wide ranging screen for novel putative GH45 sequences. This revealed that the sequences are widespread mainly in Ascomycetous fungi and have so far been found in a single major nematode lineage. Close relationships between the sequences from nematodes and fungi were found through our phylogenetic analyses. An intron position is shared by sequences from Bursaphelenchus nematodes and several Ascomycetous fungal species. CONCLUSIONS: The close phylogenetic relationships and conserved gene structure between the sequences from nematodes and fungi strongly supports the hypothesis that nematode GH45 cellulase genes were acquired via HGT from fungi. The rapid duplication and turnover of these genes within Bursaphelenchus genomes demonstrate that useful sequences acquired via HGT can become established in the genomes of recipient organisms and may open novel niches for these organisms to exploit.

Microbially formed Mn(IV) oxide as a novel adsorbent for removal of Radium.

Radioactivity of Ra isotopes in natural waters is of serious concern. Control of 226Ra concentrations in tailings ponds, which store waste from U ore extraction processes, is an important issue in mill tailings management. In this study, we tested microbially formed Mn(IV) oxide as an adsorbent for removal of Ra in water treatment. Biogenic Mn(IV) oxide (BMO) was prepared using a Mn(II)-oxidizing fungus, Coprinopsis urticicola strain Mn-2. First, adsorption experiments of Sr and Ba, as surrogates for Ra, onto BMO were conducted in aqueous NaCl solution at pH 7. Distribution coefficients for Ba and Sr were estimated to be ∼106.5 and ∼104.3 mL/g, respectively. EXAFS analysis indicated that both Sr and Ba adsorbed in inner-sphere complexes on BMO, suggesting that Ra would adsorb in a similar way. From these findings, we expected that BMO would work effectively in removal of Ra from water. Then, BMO was applied to remove Ra from mine water collected from a U mill tailings pond. Just 7.6 mg of BMO removed >98% of the 226Ra from 3 L of mine water, corresponding to a distribution coefficient of 107.4 mL/g for Ra at pH ∼7. The obtained value was convincingly high for practical application of BMO in water treatment. At the same time, the high distribution coefficient indicates that Mn(IV) oxide can be an important carrier and host phase of Ra in the environment.

Isoavenaciol and 7-hydroxy-isoavenaciol: Zn-chelating metallophores produced by root-endophytic Pezicula ericae in a Zn-accumulating plant, Aucuba japonica.

Metallophores are low-molecular-weight compounds capable of chelating heavy metals, which have recently been reported to alleviate heavy metal stress in plants. We isolated two undescribed compounds as Zn-chelating metallophores from the culture broth of the root endophytic Pezicula ericae w12-25, which was collected from a Zn-accumulating plant, Aucuba japonica Thunb. These two compounds were determined to be (3aS,4S,6aR)-3a-hydroxy-3-methylene-4-octyldihydrofuro[3,4-b]furan-2,6(3H,4H)-dione and (3S,3aS,4S,6aR)-3a-hydroxy-3-(hydroxymethyl)-4-octyldihydrofuro[3,4-b]furan-2,6(3H,4H)-dione using spectroscopic methods (HRMS, 1H and 13C NMR, and 2D NMR) and X-ray crystallography, respectively. The two compounds, classified as furofurandiones, were named isoavenaciol and 7-hydroxy-isoavenaciol. After the hydrolysis of the lactone moiety, isoavenaciol would release the carboxyl group to show Zn-chelating activity. Their antifungal activities were confirmed using Cladosporium herbarum (AHU9262).

Miscanthus sinensis contributes to the survival of Pinus densiflora seedlings at a mining site via providing a possible functional endophyte and maintaining symbiotic relationship between P. densiflora and endophytes from high soil temperature stress.

At a sedimentary site in an old mine site, Miscanthus sinensis formed patches, where Pinus densiflora seedlings could grow better compared with those outside the patches, indicating that M. sinensis would improve P. densiflora seedling establishment. The purpose of this study was to understand the mechanisms by which M. sinensis facilitates the survival of P. densiflora seedlings by considering the soil properties, heavy metal tolerance, and root endophytes in P. densiflora seedlings at the sedimentary site. The sedimentary site, which is a bare ground, contained high concentrations of Fe, indicating that plants should be exposed to Fe and high soil temperature stresses. Measurement of soil temperature revealed that M. sinensis suppressed sharp increases and alternation of soil temperature, resulting in reducing high soil temperature stress in P. densiflora seedlings. To adapt to the Fe stress environment, P. densiflora outside and inside the patches produced Fe detoxicants, including catechin, condensed tannin, and malic acid. Ceratobasidium bicorne and Aquapteridospora sp. were commonly isolated from P. densiflora seedlings outside and inside the patches as root endophytes, which might enhance Fe tolerance in the seedlings. Aquapteridospora sp., which is considered as a dark-septate endophyte (DSE), was also isolated from the roots of M. sinensis, suggesting that M. sinensis might play a source of a root endophyte to P. densiflora seedlings. Ceratobasidium bicorne could be classified into root endophytes showing symbiosis and weak pathogenicity to host plants. Therefore, high soil temperature stress would weaken P. densiflora seedlings, causing root endophytic C. bicorne to appear pathogenic. We suggested that P. densiflora could adapt to the Fe stress environment via producing Fe detoxicants, and M. sinensis would facilitate the establishment of P. densiflora seedlings in the sedimentary site by providing a DSE, Aquapteridospora sp., and maintaining symbiosis of C. bicorne from high soil temperature stress.

Fusarium kuroshium is the primary fungal symbiont of an ambrosia beetle, Euwallacea fornicatus, and can kill mango tree in Japan.

This study identifies fungi associated with Euwallacea fornicatus and determines whether these fungal species play the role of primary symbiont. E. fornicatus adults that emerged from the branches of infested trees in Okinawa main island, Japan, were collected and used to isolate fungi. Fusarium kuroshium and Penicillium citrinum were the most dominant fungal associates of females and males, respectively. F. kuroshium was much more frequently isolated from the head, including mycangia (fungus-carrying organs), of females than any other body parts. We inoculated healthy mango saplings with F. kuroshium or F. decemcellulare, both of which were symbionts of E. fornicatus females infesting mango trees. F. kuroshium decreased leaf stomatal conductance and rate of xylem sap-conduction area and increased length and area of xylem discoloration of the saplings, thereby weakening and killing some. These results suggest that F. kuroshium, a mycangial fungus of E. fornicatus, inhibits water flow in mango trees. This study is the first to report that F. kuroshium causes wilt disease in mango trees and that it is a primary fungal symbiont of E. fornicatus.

Symbiotic fungal flora in leaf galls induced by Illiciomyia yukawai (Diptera: Cecidomyiidae) and in its mycangia.

We investigated the association between a gall midge, Illiciomyia yukawai, and its symbiotic fungi on Japanese star anise, Illicium anisatum. The number of fungal species isolated from the galls increased with development of the galls, whereas those from the leaves showed a different trend. Botryosphaeria dothidea was dominant in the galls from June to October, and after that Phomopsis sp. 1, Colletotrichum sp., and Pestalotiopsis sp. became dominant. Although B. dothidea was not isolated from the leaves, it was detected from mycangia (abdominal sternite VII) of egg-laying adults at a high isolation frequency (>90%). However, B. dothidea was not isolated from mycangia of adults emerging from galls that were enclosed by plastic bags. This indicates that I. yukawai is closely associated with B. dothidea and that its newly emerged adults do not take the fungus into mycangia directly from the galls where they had developed. Also, the fungus from the fungal layers of ambrosia galls has less ability to propagate on artificial media despite the presence of its mycelial mass in mature galls.

Regional collapse of symbiotic specificity between lucanid beetles and canestriniid mites.

The intensity of interspecific interactions between hosts and symbionts varies among populations of each organism because of differences in the biotic and abiotic environment. We found geographic mosaics in associations between lucanid beetles (Dorcus rectus and Dorcus striatipennis) and symbiotic mites (Haitlingeria sp. and Sandrophela sp., respectively) that were caused by the collapse of host specificity in the northern part of Japan. Haitlingeria sp. was only collected from the surface of the exoskeleton of D. rectus in south and central Japan. Sandrophela sp. showed host specificity in southern to central Japan but was found on both beetle species in areas where Haitlingeria sp. was not found. Because Haitlingeria sp. was able to reproduce on D. rectus collected from Haitlingeria-free regions and no significant differences were observed in average temperature between the host-specific and nonspecific regions bordering on each other, we suggest that the expansion of Haitlingeria sp. in the north has been limited for unknown reasons. When both mites were placed together on D. rectus, only Haitlingeria sp. reproduced, probably because it killed Sandrophela sp., especially juveniles. Thus, we conclude that Sandrophela sp. has expanded its host use to include D. rectus in areas where Haitlingeria sp. is absent. We hypothesise that false host specificity in the canestriniids has been maintained by habitat isolation and/or aggressive behaviour toward competitors. We suggest that host-specific canestriniids provide benefits to hosts that do not develop countermeasures to exclude micro- or macroparasites from their surfaces.

Endophytic fungi associated with leaves of Betulaceae in Japan.

Diversity and species composition of endophytic fungi on leaves of 11 tree species in Betulaceae were studied, with reference to climatic, tree species, and seasonal variations. A total of 186 fungal isolates were obtained from 190 leaves collected in a subalpine forest, a cool temperate forest, and a subtropical forest in Japan, and were divided into 46 operational taxonomic units (OTUs) according to the base sequences of D1-D2 region of large subunit rDNA. The 2 most frequent OTUs were Muscodor sp. and Nemania sp. in Xylariaceae, followed by Gnomonia sp., Glomerella acutata , Apiosporopsis sp., Asteroma sp., and Cladosporium cladosporioides . The similarities of OTU composition in endophytic fungal assemblages on leaves of Betulaceae were generally low among the forests of different climatic regions. Fungal OTU compositions were relatively similar between 2 Betula species in the subalpine forest, whereas 7 tree species in the cool temperate forest were divided into 3 groups according to the similarity of endophytic fungal assemblages on the leaves, with 4 Carpinus species assigned into 2 of the 3 groups. The similarity of endophytic fungal assemblages between August and October was relatively high in the subalpine forest, whereas the seasonal changes were generally greater (i.e., the similarities among sampling dates were lower) in the cool temperate forest.

The Role of Mycangial Fungi Associated with Ambrosia Beetles (Euwallacea interjectus) in Fig Wilt Disease: Dual Inoculation of Fusarium kuroshium and Ceratocystis ficicola Can Bring Fig Saplings to Early Symptom Development.

The ambrosia beetle, Euwallacea interjectus, is a wood-boring pest and a vector of Ceratocystis ficicola, a pathogenic fungus causing fig (Ficus carica) wilt disease (FWD) in Japan. The ambrosia fungi, Fusarium kuroshium and Neocosmospora metavorans, have been frequently isolated from heads (including mycangia) of wild and reared adult female E. interjectus, respectively. However, the exact mechanisms driving FWD as well as the interactions between F. kuroshium and C. ficicola in fig orchard remain unclear. To verify the role of the mycangial fungi in the FWD progression, fig saplings were subjected to inoculation treatments (T1, F. kuroshium; T2, N. metavorans, reference positive control; T3, C. ficicola; T4, F. kuroshium + C. ficicola, realistic on-site combination). T3 and T4 saplings began wilting approximately 12 days after inoculation, leading to eventual death. Median duration from inoculation to death of the T4 saplings was approximately four days significantly faster than that of the T3 saplings. Xylem sap-conduction test indicated that dysfunction and necrosis area were considerably wider in the T4 saplings than in T3 saplings. These results demonstrate that the synergistic action of F. kuroshium and C. ficicola contributed to accelerated wilting in the saplings. Based on these discoveries, we proposed a model for system changes in the symbiosis between E. interjectus and its associated fungi in FWD in Japan.

Cytoplasmic incompatibility in the semivoltine longicorn beetle Acalolepta fraudatrix (Coleoptera: Cerambycidae) double infected with Wolbachia.

Wolbachia are obligatory endosymbiotic α-proteobacteria found in many arthropods. They are maternally inherited, and can induce reproductive alterations in the hosts. Despite considerable recent progress in studies on the associations between Wolbachia and various taxonomic groups of insects, none of the researches have revealed the effects of Wolbachia on longicorn beetles as the host insect. Acalolepta fraudatrix is a forest longicorn beetle that is distributed in East Asia. In this study, the relationship between Wolbachia and A. fraudatrix was investigated. Out of two populations of A. fraudatrix screened for Wolbachia using the genes ftsZ, wsp, and 16S rRNA, only one of the populations showed detection of all three genes indicating the presence of Wolbachia. Electron microscopy and fluorescent in situ hybridization also confirmed that the A. fraudatrix population was infected with Wolbachia. Sequencing the wsp genes derived from single insects revealed that two strains of Wolbachia coexisted in the insects based on the detection of two different sequences of the wsp gene. We designated these strains as wFra1 and wFra2. The bacterial titers of wFra1 were nearly 2-fold and 3-fold higher than wFra2 in the testes and ovaries, respectively. The two strains of Wolbachia in the insects were completely eliminated by rearing the insects on artificial diets containing 1% concentration of tetracycline for 1 generation. Reciprocal crosses between Wolbachia-infected and Wolbachia-uninfected A. fraudatrix demonstrated that only eggs produced by the crosses between Wolbachia-infected males and Wolbachia-uninfected females did not hatch, indicating that Wolbachia infecting A. fraudatrix causes cytoplasmic incompatibility in the host insect. This is the first report showing the effect of Wolbachia on reproductive function in a longicorn beetle, A. fraudatrix.

Novel Symbiotic Association Between Euwallacea Ambrosia Beetle and Fusarium Fungus on Fig Trees in Japan.

Ficus carica plantations in Japan were first reported to be infested by an ambrosia beetle species, identified as Euwallacea interjectus, in 1996. The purpose of this study was to determine the symbiotic fungi of female adults of E. interjectus emerging from F. carica trees infected with fig wilt disease (FWD). Dispersal adults (51 females) of E. interjectus, which were collected from logs of an infested fig tree in Hiroshima Prefecture, Western Japan, were separated into three respective body parts (head, thorax, and abdomen) and used for fungal isolation. Isolated fungi were identified based on the morphological characteristics and DNA sequence data. Over 13 species of associated fungi were detected, of which a specific fungus, Fusarium kuroshium, was dominant in female head (including oral mycangia). The plant-pathogenic fungus of FWD, Ceratocystis ficicola, was not observed within any body parts of E. interjectus. We further discussed the relationship among E. interjectus and its associated fungi in fig tree.

Additional description and genome analyses of Caenorhabditis auriculariae representing the basal lineage of genus Caenorhabditis.

Caenorhabditis auriculariae, which was morphologically described in 1999, was re-isolated from a Platydema mushroom-associated beetle. Based on the re-isolated materials, some morphological characteristics were re-examined and ascribed to the species. In addition, to clarify phylogenetic relationships with other Caenorhabditis species and biological features of the nematode, the whole genome was sequenced and assembled into 109.5 Mb with 16,279 predicted protein-coding genes. Molecular phylogenetic analyses based on ribosomal RNA and 269 single-copy genes revealed the species is closely related to C. sonorae and C. monodelphis placing them at the most basal clade of the genus. C. auriculariae has morphological characteristics clearly differed from those two species and harbours a number of species-specific gene families, indicating its usefulness as a new outgroup species for Caenorhabditis evolutionary studies. A comparison of carbohydrate-active enzyme (CAZy) repertoires in genomes, which we found useful to speculate about the lifestyle of Caenorhabditis nematodes, suggested that C. auriculariae likely has a life-cycle with tight-association with insects.

The Destructive Tree Pathogen Phytophthora ramorum Originates from the Laurosilva Forests of East Asia.

As global plant trade expands, tree disease epidemics caused by pathogen introductions are increasing. Since ca 2000, the introduced oomycete Phytophthora ramorum has caused devastating epidemics in Europe and North America, spreading as four ancient clonal lineages, each of a single mating type, suggesting different geographical origins. We surveyed laurosilva forests for P. ramorum around Fansipan mountain on the Vietnam-China border and on Shikoku and Kyushu islands, southwest Japan. The surveys yielded 71 P. ramorum isolates which we assigned to eight new lineages, IC1 to IC5 from Vietnam and NP1 to NP3 from Japan, based on differences in colony characteristics, gene x environment responses and multigene phylogeny. Molecular phylogenetic trees and networks revealed the eight Asian lineages were dispersed across the topology of the introduced European and North American lineages. The deepest node within P. ramorum, the divergence of lineages NP1 and NP2, was estimated at 0.5 to 1.6 Myr. The Asian lineages were each of a single mating type, and at some locations, lineages of "opposite" mating type were present, suggesting opportunities for inter-lineage recombination. Based on the high level of phenotypic and phylogenetic diversity in the sample populations, the coalescence results and the absence of overt host symptoms, we conclude that P. ramorum comprises many anciently divergent lineages native to the laurosilva forests between eastern Indochina and Japan.

Four mycangium types and four genera of ambrosia fungi suggest a complex history of fungus farming in the ambrosia beetle tribe Xyloterini.

Ambrosia beetles farm fungal cultivars (ambrosia fungi) and carry propagules of the fungal mutualists in storage organs called mycangia, which occur in various body parts and vary greatly in size and complexity. The evolution of ambrosia fungi is closely tied to the evolution and development of the mycangia that carry them. The understudied ambrosia beetle tribe Xyloterini included lineages with uncharacterized ambrosia fungi and mycangia, which presented an opportunity to test whether developments of different mycangium types in a single ambrosia beetle lineage correspond with concomitant diversity in their fungal mutualists. We collected representatives of all three Xyloterini genera (Trypodendron, Indocryphalus, and Xyloterinus politus) and characterized their ambrosia fungi in pure culture and by DNA sequencing. The prothoracic mycangia of seven Trypodendron species all yielded Phialophoropsis (Microascales) ambrosia fungi, including three new species, although these relationships were not all species specific. Indocryphalus mycangia are characterized for the first time in the Asian I. pubipennis. They comprise triangular prothoracic cavities substantially smaller than those of Trypodendron and unexpectedly carry an undescribed species of Toshionella (Microascales), which are otherwise ambrosia fungi of Asian Scolytoplatypus (Scolytoplatypodini). Xyloterinus politus has two different mycangia, each with a different ambrosia fungus: Raffaelea cf. canadensis RNC5 (Ophiostomatales) in oral mycangia of both sexes and Kaarikia abrahamsonii (Sordariomycetes, genus incertae sedis with affinity for Distoseptisporaceae), a new genus and species unrelated to other known ambrosia fungi, in shallow prothoracic mycangia of females. In addition to their highly adapted mycangial mutualists, Trypodendron and X. politus harbor a surprising diversity of facultative symbionts in their galleries, including Raffaelea. A diversity of ambrosia fungi and mycangia suggest multiple ancestral cultivar captures or switches in the history of tribe Xyloterini, each associated with unique adaptations in mycangium anatomy. This further supports the theory that developments of novel mycangium types are critical events in the evolution of ambrosia beetles and their coadapted fungal mutualists.

Gut bacterial and fungal communities in ground-dwelling beetles are associated with host food habit and habitat.

Beetles (Coleoptera) have the highest species diversity among all orders, and they have diverse food habits. Gut microbes may have contributed to this diversification of food habits. Here, we identified the pattern of the relationship between ground-dwelling beetles and their gut microbial communities (bacteria and fungi) in the field. We collected 46 beetle species of five families from secondary deciduous forests and grasslands in Japan and extracted microbial DNA from whole guts for amplicon sequencing. The gut bacterial and fungal communities differed among all habitats and all food habits of their hosts (carnivores, herbivores, omnivores, and scavengers) except for the fungal communities between carnivores and scavengers. Specifically, the abundant bacterial group varied among food habits: Xanthomonadaceae were abundant in scavengers, whereas Enterobacteriaceae were abundant in carnivores and herbivores. Phylogenetically closely related beetles had phylogenetically similar communities of Enterobacteriaceae, suggesting that the community structure of this family is related to the evolutionary change in beetle ecology. One of the fungal groups, Yarrowia species, which has been reported to have a symbiotic relationship with silphid beetles, was also detected from various carnivorous beetles. Our results suggest that the symbiotic relationships between ground-dwelling beetles and these microbes are widespread.

Root-endophytic Chaetomium cupreum chemically enhances aluminium tolerance in Miscanthus sinensis via increasing the aluminium detoxicants, chlorogenic acid and oosporein.

Miscanthus sinensis Andersson is a pioneer plant species that grows naturally at mining sites. Miscanthus sinensis can detoxify aluminium (Al) by producing phytosiderophores, such as chlorogenic acid, citric acid, and malic acid, and localizing Al in cell walls. Root-endophytic Chaetomium cupreum, which produces microbial siderophores, enhances Al tolerance in M. sinensis. However, we could not determine whether the siderophores produced by C. cupreum actually enhance Al tolerance in M. sinensis, because the microbial siderophores have not yet been identified in previous research. The purpose of this study was to clarify how C. cupreum chemically increases Al tolerance in M. sinensis under acidic mining site conditions, especially considering siderophores. Using instrumental analyses, the siderophore produced by C. cupreum was identified as oosporein. Comparison of the stability constant between Al and phytosiderophores and oosporein indicated that oosporein could detoxify Al similarly to chlorogenic acid, which shows higher stability constant than citric acid and malic acid. Inoculation test of C. cupreum onto M. sinensis in acidic mine soil showed that C. cupreum promoted seedling growth, and enhanced Al tolerance via inducing chlorogenic-acid production and producing oosporein. These results suggested that C. cupreum could chemically enhance Al tolerance and might promote growth via reducing excessive Al in cell walls, the main site of Al accumulation. In addition, the chemical enhancement of Al tolerance by C. cupreum might be important for M. sinensis to adapt to acidic mining sites.