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High diversity and low specificity of chaetothyrialean fungi in carton galleries in a neotropical ant-plant association.

Nepel M, Voglmayr H, Schönenberger J, Mayer VE - PLoS ONE (2014)

Bottom Line: The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae.In order to characterise the specificity of the ant-fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences.This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis.

View Article: PubMed Central - PubMed

Affiliation: Division of Structural and Functional Botany, Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.

ABSTRACT
New associations have recently been discovered between arboreal ants that live on myrmecophytic plants, and different groups of fungi. Most of the - usually undescribed - fungi cultured by the ants belong to the order Chaetothyriales (Ascomycetes). Chaetothyriales occur in the nesting spaces provided by the host plant, and form a major part of the cardboard-like material produced by the ants for constructing nests and runway galleries. Until now, the fungi have been considered specific to each ant species. We focus on the three-way association between the plant Tetrathylacium macrophyllum (Salicaceae), the ant Azteca brevis (Formicidae: Dolichoderinae) and various chaetothyrialean fungi. Azteca brevis builds extensive runway galleries along branches of T. macrophyllum. The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae. In order to characterise the specificity of the ant-fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences. This gave 128 different fungal genotypes, 78% of which were clustered into three monophyletic groups. The most common fungus (either genotype or approximate species-level OTU) was found in the runway galleries of 63% of the investigated ant colonies. This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis.

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Carton runway galleries built by Azteca brevis ants, consisting of mycelia and various organic particles.(A, B) Galleries on the lower side of branches of Tetrathylacium macrophyllum: note the scattered circular openings in the gallery walls. (B) Alarmed workers wait with open mandibles below the holes for prey or intruders. (C, D) Scanning electron microscope images of the gallery walls infused with different types of hyphae. (E, F) Light-microscope images of both hyphal types: (E) thin-walled hyaline hyphae typical for carton clades 2 and 3; (F) pigmented thick-walled hyphae typical for carton clade 1 (see Figure 2–3). Bars: (A, B) 1 cm; (C, D) 100 µm; (E, F) 20 µm.
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pone-0112756-g001: Carton runway galleries built by Azteca brevis ants, consisting of mycelia and various organic particles.(A, B) Galleries on the lower side of branches of Tetrathylacium macrophyllum: note the scattered circular openings in the gallery walls. (B) Alarmed workers wait with open mandibles below the holes for prey or intruders. (C, D) Scanning electron microscope images of the gallery walls infused with different types of hyphae. (E, F) Light-microscope images of both hyphal types: (E) thin-walled hyaline hyphae typical for carton clades 2 and 3; (F) pigmented thick-walled hyphae typical for carton clade 1 (see Figure 2–3). Bars: (A, B) 1 cm; (C, D) 100 µm; (E, F) 20 µm.

Mentions: There is evidence that the fungi cultivated within the domatia are used as a food source [8], whereas those in the carton-like material do not appear to be consumed. Rather, they seem to serve to stabilise the carton mechanically. Carton structures with fungi were first documented in nest walls of the European ant Lasius fuliginosus inside hollow tree-trunks [1], [9], [10]. They have since been found in the walls of free-hanging canopy ant nests in the Palaeotropics [11], [12] and in the Neotropics, where ants use fungus-infused, carton-like material to construct tunnel systems called “runway galleries” along branches of their host trees [6], [13], [14] (Figure 1A–D).


High diversity and low specificity of chaetothyrialean fungi in carton galleries in a neotropical ant-plant association.

Nepel M, Voglmayr H, Schönenberger J, Mayer VE - PLoS ONE (2014)

Carton runway galleries built by Azteca brevis ants, consisting of mycelia and various organic particles.(A, B) Galleries on the lower side of branches of Tetrathylacium macrophyllum: note the scattered circular openings in the gallery walls. (B) Alarmed workers wait with open mandibles below the holes for prey or intruders. (C, D) Scanning electron microscope images of the gallery walls infused with different types of hyphae. (E, F) Light-microscope images of both hyphal types: (E) thin-walled hyaline hyphae typical for carton clades 2 and 3; (F) pigmented thick-walled hyphae typical for carton clade 1 (see Figure 2–3). Bars: (A, B) 1 cm; (C, D) 100 µm; (E, F) 20 µm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232418&req=5

pone-0112756-g001: Carton runway galleries built by Azteca brevis ants, consisting of mycelia and various organic particles.(A, B) Galleries on the lower side of branches of Tetrathylacium macrophyllum: note the scattered circular openings in the gallery walls. (B) Alarmed workers wait with open mandibles below the holes for prey or intruders. (C, D) Scanning electron microscope images of the gallery walls infused with different types of hyphae. (E, F) Light-microscope images of both hyphal types: (E) thin-walled hyaline hyphae typical for carton clades 2 and 3; (F) pigmented thick-walled hyphae typical for carton clade 1 (see Figure 2–3). Bars: (A, B) 1 cm; (C, D) 100 µm; (E, F) 20 µm.
Mentions: There is evidence that the fungi cultivated within the domatia are used as a food source [8], whereas those in the carton-like material do not appear to be consumed. Rather, they seem to serve to stabilise the carton mechanically. Carton structures with fungi were first documented in nest walls of the European ant Lasius fuliginosus inside hollow tree-trunks [1], [9], [10]. They have since been found in the walls of free-hanging canopy ant nests in the Palaeotropics [11], [12] and in the Neotropics, where ants use fungus-infused, carton-like material to construct tunnel systems called “runway galleries” along branches of their host trees [6], [13], [14] (Figure 1A–D).

Bottom Line: The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae.In order to characterise the specificity of the ant-fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences.This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis.

View Article: PubMed Central - PubMed

Affiliation: Division of Structural and Functional Botany, Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.

ABSTRACT
New associations have recently been discovered between arboreal ants that live on myrmecophytic plants, and different groups of fungi. Most of the - usually undescribed - fungi cultured by the ants belong to the order Chaetothyriales (Ascomycetes). Chaetothyriales occur in the nesting spaces provided by the host plant, and form a major part of the cardboard-like material produced by the ants for constructing nests and runway galleries. Until now, the fungi have been considered specific to each ant species. We focus on the three-way association between the plant Tetrathylacium macrophyllum (Salicaceae), the ant Azteca brevis (Formicidae: Dolichoderinae) and various chaetothyrialean fungi. Azteca brevis builds extensive runway galleries along branches of T. macrophyllum. The carton of the gallery walls consists of masticated plant material densely pervaded by chaetothyrialean hyphae. In order to characterise the specificity of the ant-fungus association, fungi from the runway galleries of 19 ant colonies were grown as pure cultures and analyzed using partial SSU, complete ITS, 5.8S and partial LSU rDNA sequences. This gave 128 different fungal genotypes, 78% of which were clustered into three monophyletic groups. The most common fungus (either genotype or approximate species-level OTU) was found in the runway galleries of 63% of the investigated ant colonies. This indicates that there can be a dominant fungus but, in general, a wider guild of chaetothyrialean fungi share the same ant mutualist in Azteca brevis.

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