Crop optimization in insect agriculture:
Mutualistic adaptations in fungi cultivated by leaf-cutting ants
Henrik H. de Fine LichtPost doc. Insect Pathology and Biological Control, Section for Organismal Biology, Institute for Plant and Environmental Sciences, University of Copenhagen
Ca. 50 million years ago (MYA) fungus-growing ants began using plant material to cultivate basidiomycete fungi for food in underground fungus garden chambers. More recently, ca. 25 MYA a crown group of the cultivated fungi evolved inflated hyphal tips (gongylidia) as a specific symbiotic adaptation that the ants feed on. The evolution of these morphological adaptations in the cultivated fungi coincides with transitions in forage material collection, as the ants shifted from primarily collecting dry leaf litter and caterpillar feces to cutting fresh leaves and effectively becoming herbivores. The ability to utilize fresh leaves required a number of adaptations in the ants but also of the fungal cultivar to overcome physical and chemical plant defenses. Using comparative morphology, qPCR, RNA-seq and transcriptome analysis to reveal the evolutionary adaptations of the fungus Leucoagaricus gongylophorus cultivated by the leaf-cutting ant Acromyrmex echinatior, I find that the molecular signatures of gongylidia morphogenesis, physiological dependency, and plant degrading enzyme modifications are consistent with profound ant mediated coevolutionary selection on fungus-growing ant cultivars.
