Recent advances in ant–plant symbioses

Last updated: 7 Oct, 2014

In ant–plant symbioses plants provide housing in the form of specialised hollowed structures and nutrition in the form of food bodies and nectar. In return, the inhabiting ants protect plants against herbivores, and occasionally provide them with nutrients. Two recent papers published in New Phytologist provide insights into recent advances made in ant–plant symbioses.

Ants protect acacia plants against pathogens

González-Teuber M, Kaltenpoth M, Boland W. 2014. Mutualistic ants as an indirect defence against leaf pathogens. New Phytologist, in press.

Researchers at the Max Planck Institute for Chemical Ecology investigated the relationship between Acacia hindsii and the inhabitant ants of the genus Pseudomyrmex. They found that in addition to providing protection against herbivores, these ants also keep harmful leaf pathogens in check. The researchers found that the presence of ants greatly reduced bacterial abundance on surfaces of leaves and had a visibly positive effect on plant health. The researchers have thus added another level of interaction to the symbiosis between ants and their host plant.

Mutualistic Pseudomyrmex ferrugineus ants on an acacia plant. The ants love nectar from the plant's extrafloral nectaries. Copyright: Martin Heil, CINVESTAV, Irapuata, Mexico.

Read the press release in full here: http://www.ice.mpg.de/ext/1057.html

This article was also reported in the Science and technology column of The Economist: http://www.economist.com/news/science-and-technology/21594954-another-twist-one-natures-best-known-partnerships-protect-and-survive

Current issues in the evolutionary ecology of ant–plant symbioses

Mayer VE, Frederickson ME, McKey D, Blatrix R. 2014. Current issues in the evolutionary ecology of ant–plant symbioses. New Phytologist, in press.

In this Tansley review Mayer et al. provide an overview of recent research in ant–plant symbioses, focusing on three areas. First, the nutritional ecology of plant-ants, which is based not only on plant-derived food rewards, but also on inputs from other symbiotic partners, in particular fungi and possibly bacteria. Food and protection are the most important ‘currencies’ exchanged between partners and they drive the nature and evolution of the relationships. Secondly, studies of conflict and cooperation in ant–plant symbioses have contributed key insights into the evolution and maintenance of mutualism, particularly how partner-mediated feedbacks affect the specificity and stability of mutualisms. There is little evidence that mutualistic ants or plants are under selection to cheat, but the costs and benefits of ant–plant interactions do vary with environmental factors, making them vulnerable to natural or anthropogenic environmental change. Thus, thirdly, ant–plant symbioses should be considered good models for investigating the effects of global change on the outcome of mutualistic interactions.

Although the ant Crematogaster nigriceps sterilizes its host plant, the African myrmecophyte Acacia drepanolobium, it increases its fitness because it colonizes mostly young trees and protects them against browsing. Photo: Megan Frederickson, University of Toronto, Toronto, Canada. (Figure 4 in Mayer et al.).

Read the article by Mayer et al. in full for free here: http://onlinelibrary.wiley.com/doi/10.1111/nph.12690/full

All Tansley reviews are free to access and the full catalogue of published Tansley reviews can be searched here: http://www.newphytologist.org/reviews.