The Genetics of Arbuscular Mycorrhizal Fungi

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Bio-fertilizers are an eco-friendly, sustainable way to boost plant yields. This has attracted considerable attention from biotech companies towards particularly the Arbuscular Mycorrhizal Fungi (AMF); a group of multinucleated and seemingly asexual fungi that form beneficial associations with the roots of most plants. In the past 6 years my research used cutting edge-single nucleus sequencing and comparative genomics to understand the genetics of AMF. We demonstrated that some AMF strains, which we refer to as AM dikaryons, carry thousands of nuclei that are copies of two parental genotypes in one large cell. Each nucleus harbors a mating-type locus similar to those that dictate sexual identity in other fungi, indicating that AMF can undergo sexual reproduction. We now aim to use this biological information to enhance the environmental application of these fungi. To achieve this, however, key questions related to origin and function of AM dikaryons and their genomes remain to be understood. The long-term goal of my research program is to elucidate the forces driving nuclear diversity and genome evolution in AMF. My lab will work towards this goal by focusing on three related objectives: (1) To investigate the impact of AM dikaryosis on the biology of the fungal and plant partners. We will perform transcriptomics and phenotype analyses to identify how two co-existing nuclear genotypes contribute to the symbiotic potential of AM dikaryons across life-stages and plant hosts. (2) To identify the origin and evolution of the two nuclear genotypes that co-exist in AM dikaryons. We will obtain and compare high-quality genome data from AM dikaryons, AM homokaryons and individual nuclei isolated from dikaryotic strains using long-read sequencing. This data will allow us to identify the evolutionary origins of AM dikaryons, compare their mode of evolution with those of homokaryotic relatives, and comprehend how nuclei co-evolve within the dikaryotic mycelium. (3) To identify the genetic determinants that trigger nuclear exchange in AMF. We will use proteomics and microscopy approaches to determine what triggers AMF strains to cross (mate) and will aim to use this information to generate genetically new strains. The data generated in this program will help elucidate the mechanisms that generate genetic and genomic diversity in these organisms, thereby contributing to their environmental application and to our understanding of complex genetic systems. Through the proposed research, HQP will gain experience with cutting edge methods (single-cell/nucleus analyses), best in class sequencing tools (MinION, 10X Chromium) and programming skills (Python, Perl), and with proteomics and microscopy approaches. My program will also actively involve trainees in outreach activities, including some that address barriers to EDI. With this highly complementary skillset, HQP will continue to move on to impactful positions in industry, government and academia.