Wednesday, October 31, 2018 at 12:20pm
Associate Professor, Cornell University
My research focuses on basic biology and evolution of arbuscular mycorrhizal (AM) fungi (phylum Glomeromycota) and their bacterial endosymbionts.
AM fungi engage in arbuscular mycorrhiza, a mutualistic symbiotic association involving the majority of the land plants, including many crop species. The fungal contribution to this association entails the facilitation of plant mineral nutrient uptake, which is believed to have been instrumental in the transition of the early plants to the terrestrial habitat. Today, AM fungi hold a promise of becoming a substitute for chemical fertilizers in agriculture, landscaping and restoration of habitats disturbed by humans. Yet our understanding of their biology is perplexingly limited.
One of the biggest mysteries in the biology of AM fungi is their reproductive mode. Based on the morphological evidence, or rather the absence of any evidence to the contrary, we believe that AM fungi reproduce asexually, and have been doing so throughout their entire evolutionary history. We are in the process of applying tools of population genetics and phylogenetics to test this hypothesis.
AM fungi exhibit an unusual within-individual polymorphism of rRNA-coding genes consistent with a molecular pattern of relaxation of concerted evolution, the recombination-driven process responsible for homogenization of rRNA gene repeats within individual genomes and among individuals of a recombining population. Understanding of the reproductive mode in AM fungi taken together with a study of genome structure will help to explain this phenomenon.
Unlike most other fungi, Glomeromycota harbor bacterial endosymbionts. Elucidation of the role of endobacteria in Glomeromycota biology and evolution is important for understanding arbuscular mycorrhizae.