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Laccase detoxification mediates the nutritional alliance between leaf-cutting ants and fungus-garden symbionts

de Fine Licht, Henrik Hjarvard LU ; Schiott, Morten ; Rogowska-Wrzesinska, Adelina ; Nygaard, Sanne ; Roepstorff, Peter and Boomsma, Jacobus J. (2013) In Proceedings of the National Academy of Sciences 110(2). p.583-587
Abstract
Leaf-cutting ants combine large-scale herbivory with fungus farming to sustain advanced societies. Their stratified colonies are major evolutionary achievements and serious agricultural pests, but the crucial adaptations that allowed this mutualism to become the prime herbivorous component of neotropical ecosystems has remained elusive. Here we show how coevolutionary adaptation of a specific enzyme in the fungal symbiont has helped leaf-cutting ants overcome plant defensive phenolic compounds. We identify nine putative laccase-coding genes in the fungal genome of Leucocoprinus gongylophorus cultivated by the leaf-cutting ant Acromyrmex echinatior. One of these laccases (LgLcc1) is highly expressed in the specialized hyphal tips... (More)
Leaf-cutting ants combine large-scale herbivory with fungus farming to sustain advanced societies. Their stratified colonies are major evolutionary achievements and serious agricultural pests, but the crucial adaptations that allowed this mutualism to become the prime herbivorous component of neotropical ecosystems has remained elusive. Here we show how coevolutionary adaptation of a specific enzyme in the fungal symbiont has helped leaf-cutting ants overcome plant defensive phenolic compounds. We identify nine putative laccase-coding genes in the fungal genome of Leucocoprinus gongylophorus cultivated by the leaf-cutting ant Acromyrmex echinatior. One of these laccases (LgLcc1) is highly expressed in the specialized hyphal tips (gongylidia) that the ants preferentially eat, and we confirm that these ingested laccase molecules pass through the ant guts and remain active when defecated on the leaf pulp that the ants add to their gardens. This accurate deposition ensures that laccase activity is highest where new leaf material enters the fungus garden, but where fungal mycelium is too sparse to produce extracellular enzymes in sufficient quantities to detoxify phenolic compounds. Phylogenetic analysis of LgLcc1 ortholog sequences from symbiotic and free-living fungi revealed significant positive selection in the ancestral lineage that gave rise to the gongylidia-producing symbionts of leaf-cutting ants and their non-leaf-cutting ant sister group. Our results are consistent with fungal preadaptation and subsequent modification of a particular laccase enzyme for the detoxification of secondary plant compounds during the transition to active herbivory in the ancestor of leaf-cutting ants between 8 and 12 Mya. (Less)
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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
gene cooption, polyphenols
in
Proceedings of the National Academy of Sciences
volume
110
issue
2
pages
583 - 587
publisher
National Acad Sciences
external identifiers
  • wos:000313906600045
  • scopus:84872203030
  • pmid:23267060
ISSN
1091-6490
DOI
10.1073/pnas.1212709110
language
English
LU publication?
yes
id
5824e908-8cd9-4f46-8c6b-a412c74da2d3 (old id 3590753)
date added to LUP
2016-04-01 10:34:53
date last changed
2020-11-16 02:50:04
@article{5824e908-8cd9-4f46-8c6b-a412c74da2d3,
  abstract     = {Leaf-cutting ants combine large-scale herbivory with fungus farming to sustain advanced societies. Their stratified colonies are major evolutionary achievements and serious agricultural pests, but the crucial adaptations that allowed this mutualism to become the prime herbivorous component of neotropical ecosystems has remained elusive. Here we show how coevolutionary adaptation of a specific enzyme in the fungal symbiont has helped leaf-cutting ants overcome plant defensive phenolic compounds. We identify nine putative laccase-coding genes in the fungal genome of Leucocoprinus gongylophorus cultivated by the leaf-cutting ant Acromyrmex echinatior. One of these laccases (LgLcc1) is highly expressed in the specialized hyphal tips (gongylidia) that the ants preferentially eat, and we confirm that these ingested laccase molecules pass through the ant guts and remain active when defecated on the leaf pulp that the ants add to their gardens. This accurate deposition ensures that laccase activity is highest where new leaf material enters the fungus garden, but where fungal mycelium is too sparse to produce extracellular enzymes in sufficient quantities to detoxify phenolic compounds. Phylogenetic analysis of LgLcc1 ortholog sequences from symbiotic and free-living fungi revealed significant positive selection in the ancestral lineage that gave rise to the gongylidia-producing symbionts of leaf-cutting ants and their non-leaf-cutting ant sister group. Our results are consistent with fungal preadaptation and subsequent modification of a particular laccase enzyme for the detoxification of secondary plant compounds during the transition to active herbivory in the ancestor of leaf-cutting ants between 8 and 12 Mya.},
  author       = {de Fine Licht, Henrik Hjarvard and Schiott, Morten and Rogowska-Wrzesinska, Adelina and Nygaard, Sanne and Roepstorff, Peter and Boomsma, Jacobus J.},
  issn         = {1091-6490},
  language     = {eng},
  number       = {2},
  pages        = {583--587},
  publisher    = {National Acad Sciences},
  series       = {Proceedings of the National Academy of Sciences},
  title        = {Laccase detoxification mediates the nutritional alliance between leaf-cutting ants and fungus-garden symbionts},
  url          = {http://dx.doi.org/10.1073/pnas.1212709110},
  doi          = {10.1073/pnas.1212709110},
  volume       = {110},
  year         = {2013},
}