<i>Chaetomium elatum</i> (Kunze: Chaetomiaceae) as a root‐colonizing fungus in avocado: is it a mutualist, cheater, commensalistic associate, or pathogen?

Violi, Helen A.; Menge, J. A.; Beaver, Robert J.

doi:10.3732/ajb.94.4.690

Cited by 26 publications

(22 citation statements)

References 58 publications

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“…Of these FCspecific OTUs, many were assigned to phylogenetic groups harboring known phytotoxic or phytopathogenic microorganisms, such as the fungal genera Periconia, Curvularia, and Aspergillus, the fungal order Pleosporales, the fungal family Chaetomiaceae, and the bacterial class Gammaproteobacteria (58)(59)(60)(61)(62)(63). While these results do not directly implicate microorganisms in the creation and/or maintenance of Namib Desert FCs, they remain consistent with the hypothesis that microorganisms play a role in the phenomenon.…”

Section: Discussionsupporting

confidence: 70%

“…Finally, we have identified microorganisms that are present solely in FC soils and that may play a role in the fairy circle phenomenon. Many of the OTUs found only in FCs are related to known phytopathogen groups (the fungal genera Periconia, Curvularia, and Aspergillus, the fungal order Pleosporales and family Chaetomiaceae, and the bacterial class Gammaproteobacteria [58][59][60][61][62][63]), suggesting that they may play a role in this phenomenon. To further investigate this hypothesis, the FC-specific phylotypes should be isolated and used in controlled greenhouse experiments to identify patterns related to phytopathology (64).…”

Section: Discussionmentioning

confidence: 99%

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Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils

Walt

Johnson

Cowan

et al. 2016

Appl Environ Microbiol

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Fairy circles (FCs) are barren circular patches of soil surrounded by grass species. Their origin is poorly understood. FCs feature in both the gravel plains and the dune fields of the Namib Desert. While a substantial number of hypotheses to explain the origin and/or maintenance of fairy circles have been presented, none are completely consistent with either their properties or their distribution. In this study, we investigated the hypothesis that FC formation in dunes and gravel plains is due to microbial phytopathogenesis. Surface soils from five gravel plain and five dune FCs, together with control soil samples, were analyzed using high-throughput sequencing of bacterial/archaeal (16S rRNA gene) and fungal (internal transcribed spacer [ITS] region) phylogenetic markers. Our analyses showed that gravel plain and dune FC microbial communities are phylogenetically distinct and that FC communities differ from those of adjacent vegetated soils. Furthermore, various soil physicochemical properties, particularly the pH, the Ca, P, Na, and SO 4 contents, the soil particle size, and the percentage of carbon, significantly influenced the compositions of dune and gravel plain FC microbial communities, but none were found to segregate FC and vegetated soil communities. Nevertheless, 9 bacterial, 1 archaeal, and 57 fungal phylotypes were identified as FC specific, since they were present within the gravel plain and dune FC soils only, not in the vegetated soils. Some of these FC-specific phylotypes were assigned to taxa known to harbor phytopathogenic microorganisms. This suggests that these FC-specific microbial taxa may be involved in the formation and/or maintenance of Namib Desert FCs. IMPORTANCEFairy circles (FCs) are mysterious barren circular patches of soil found within a grass matrix in the dune fields and gravel plains of the Namib Desert. Various hypotheses attempting to explain this phenomenon have been proposed. To date, however, none have been successful in fully explaining the etiology of FCs, particularly since gravel plain FCs have been largely ignored. In this study, we investigated the hypothesis that microorganisms could be involved in the FC phenomenon through phytopathogenesis. We show that the microbial communities in FC and control vegetated soil samples were significantly different. Furthermore, we detected 67 FC-specific microbial phylotypes, i.e., phylotypes present solely in both gravel plain and dune FC soils, some of which were closely related to known phytopathogens. Our results, therefore, demonstrate that microorganisms may play a role in the formation and/or maintenance of Namib Desert FCs, possibly via phytopathogenic activities. (1, 2). Common in the Namib Desert, and recently observed in the Australian outback (3), FCs are limited to arid areas that receive between 50 and 100 mm precipitation per annum. FCs are nonpermanent; they typically appear, enlarge, and disappear, with an estimated life span ranging from 22 to 60 years (4, 5).Although FCs were first reported in the 1970...

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Section: Discussionsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils

Walt

Johnson

Cowan

et al. 2016

Appl Environ Microbiol

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“…Re-synthesis in vitro co-culture system will be required, however, to confirm their endophytism and infection structure in roots. In addition, increasing reports have demonstrated that some novel groups of DSEs are classified into the order Pleosporales (Jumpponen 2001;Violi et al 2007;Porras-Alfaro et al 2008). In our study, molecular phylogeny revealed that four genotypes (Genotype 13-16) fell into the order Pleosporales (data not shown), which may act as potential DSEs but also waiting to be verified by using in vitro experimentation.…”

Section: Resultscontrasting

confidence: 50%

Symbiotic fungi in roots ofArtemisia annuawith special reference to endophytic colonizers

Youxiang

Chen

2011

Plant Biosystems - An International Journal Dealing with all As

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Advances on plant-fungal interactions reveal that root symbiotic fungi actively modulate host growth, resistance response and secondary metabolism. Artemisia annua has been widely recognized as an important medicinal plant for artemisinin production, yet little is known about the fungal consortium associated with roots of A. annua. In this article, microscopic and culture-dependant methods were used to evaluate the identity and taxonomic affinities of root symbiotic fungi. Morphological evidence confirmed that arbuscular mycorrhizal fungi were dominant fungal group in naturally regenerated roots, but low colonization frequency in planted roots. Dark septate endophytes (DSEs) were easily found, which were characterized with dark pigmented hypha and a sclerotium-like structure in root cortex, and other endophytic fungi also occurred. A total of 36 isolates were recovered. Combined morphological and molecular identification (based on ITS sequences) determined 21 fungal taxa (genotype), which were placed into numerous lineages of Ascomycota. The best BLAST match indicated that almost half of total taxa were closely related to undescribed fungi, some of them may act as novel DSEs but experimental data were warranted. Interestingly, remarkable difference of fungal community associated with two types of roots was examined and no culturable fungi overlapped. Our findings provide some additional evidence that DSEs and other root endophytes may be as common as mycorrhizal fungi. Recovered fungi as raw materials for bioassay of endophytes-mediated promotion of artemisinin content in A. annua will be conducted in further research.

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“…Root-colonizing fungi may have various lifestyles, depending on the plant's physiology and the availability of resources (Redman et al 2001;Violi et al 2007); this certainly may be the case for endophytic fungi.…”

Section: Discussionmentioning

confidence: 99%

Associations between microfungal endophytes and roots: do structural features indicate function?

Peterson

Wagg

Pautler

2008

Botany

110

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Roots encounter a plethora of microorganisms in the soil environment that are either deleterious, neutral, or beneficial to plant growth. Root endophytic fungi are ubiquitous. These include dark septate endophytes whose role in plant growth and the maintenance of plant communities is largely unknown. The objectives of this review were to assess the structural features of the interactions between dark septate endophytic fungi and the roots of both angiopsperms and conifers, and to suggest avenues for further research. Several light microscopy studies of endophyte-root interactions have revealed a variety of structural features, depending on host species and plant growth conditions. In some cases, when fungal hyphae enter roots they cause cell breakdown, whereas in other situations there is little noticeable effect. In some tree species, associations with these endophytes may mimic ectomycorrhizas or ectendomycorrhizas. The few ultrastructural studies indicate that intracellular hyphae lack a host-derived perifungal membrane and interfacial matrix material, features typical of biotrophic fungus -plant cell interactions. This raises questions concerning nutrient exchange between these fungi and plant cells. Further research in this area is needed. New approaches that include molecular cytology and livecell imaging are needed to determine early changes in plant cells when challenged with these fungi.Résumé : Dans l'environnement édaphique, les racines rencontrent une pléthore de microorganismes néfastes, neutres ou bénéfiques à la croissance des plantes. Les endophytes racinaires sont ubiquistes. Ceux-ci incluent les endophytes foncés septés, dont on connaît mal le rôle dans la croissance des plantes et le maintien des communautés végétales. Dans cette revue, les auteurs ont pour objectifs d'évaluer les caractéristiques structurales des interactions entre les champignons endophytes foncés septés et les racines des angiospermes aussi bien que des gymnospermes, et de suggérer des avenues pour les recherches futures. L'étude en microscopie photonique des interactions endophyte-racine se retrouve dans plusieurs études qui montrent qu'une variété de caractéristiques structurales dépendent des espèces hôtes et des conditions de croissance. Dans certains cas, lorsque les hyphes pénètrent les racines, elles causent une rupture des cellules, alors que dans d'autres situations, il y a peu d'effet notable. Chez certaines espèces d'arbres, l'association avec ces endophytes peut ressembler à des ectomycorhizes ou à des ectendomycorhizes. Les rares études ultrastructurales indiquent que les hyphes intracellulaires ne possèdent pas d'enveloppe périfongique dérivée de l'hôte et de matériel matriciel interfacial, deux caractéristiques propres aux interactions cellulaires biotrophiques champignon-plante. Ceci soulève la question quant aux échanges entre ces champignons et les cellules végétales. D'autres recherches sur ces aspects sont nécessaires. On doit dé-velopper de nouvelles approches incluant la cytologie moléculaire et l'image...

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Chaetomium elatum (Kunze: Chaetomiaceae) as a root‐colonizing fungus in avocado: is it a mutualist, cheater, commensalistic associate, or pathogen?

Cited by 26 publications

References 58 publications

Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils

Unique Microbial Phylotypes in Namib Desert Dune and Gravel Plain Fairy Circle Soils

Symbiotic fungi in roots ofArtemisia annuawith special reference to endophytic colonizers

Associations between microfungal endophytes and roots: do structural features indicate function?

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