Speaker: Brian Dilkes, Purdue University professor in biochemistry

Title: Replaying the evolutionary tape to discover structure function relationships in plants

Abstract: One problem in establishing the identities of genes responsible for the adaptive variation within species is our incomplete knowledge of gene functions. Using the beautiful resources of experimental maize genetics, we are approaching the establishment of gene functional annotations directly from natural variation through pathway-level approaches that test hypothesis about natural variants. Knowing the biological pathway affected by a natural variant, aka a mutant, radically accelerates the discovery of causative polymorphisms. Rather than using ‘omics experiments as hypothesis generating experiments, we are using them in combination with informatics, population genetics, and molecular biology to carry out genome wide association studies (GWAS) where the trait can be the activation state of a signaling pathway, the homeostatic response to metabolic limitation, or an epistatic interaction with a gene of known function. This approach demonstrates regulatory mechanisms operating within the normal physiological range of an organism. This has detected novel regulation affected by natural variation in processes as diverse as porphyrin metabolism and transposon regulated gene expression. We are simultaneously looking to use conservation of function across organisms to assist in the search for genes affecting natural variation. The evolution of adaptation across lineages repeatedly, and recursively, results from mutations in genes. Instead of waiting to find or observe this kind of replication, we have used studies of natural variation in multiple species as replicate observations of gene function. By testing whether grouping orthologous genes across a phylogeny contains information about their functional consequences this both uses and tests the functions of orthologs in trait variation. We have applied this approach to very old problems, like moving high energy electrons or obtaining, accumulating, or excluding elements from the environment. 

Host: Dior Kelley, genetics, development and cell biology associate professor