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Wellington Muchero

Date & Location: January 13, 2020, at 4p; Room 1200 Molecular Plant Sciences Building

Subject: Deep orthology underlies expression of homologous phenotypes across highly divergent organisms including plants and humans

Host: Greg Bonito

About the Speaker

University: Oak Ridge National Laboratory

Abstract: Using whole-genome resequencing targeting >1,500 undomesticated Populus genotypes, we created genome-wide association mapping and quantitative trait loci mapping platforms to link nucleotide-level sequence variants to trait expression with unprecedented precision. Single-gene mapping resolution is enabled by rapid linkage disequilibrium decay across the Populus genome complemented by a panel of >27 million markers which, in combination, enables inference of gene function with no need for a priori assumptions or reliance on homology-based functional annotation.

We deployed this platform to link mutations to traits including cell wall chemistry , disease resistance, mycorrhization, secondary metabolite biosynthesis and prediction of cis- and trans-regulatory elements underlying transcript abundance across multiple plant tissues. In addition, this platform has revealed numerous instances of evolutionarily-related proteins with low-levels of homology performing the same function in distantly related organisms including plants and humans. Examples include proteins involved in DNA repair, cell division, cell adhesion, tissue regeneration and immunological responses during parasitism, symbiont recruitment and gamete fertilization. In addition to the above, a case study will be presented illustrating shared molecular function between the human and plant DiGeorge Critical Region 14 protein whose deletion is lethal in the homozygous condition in animal systems. In contrast, homozygous deletion in plants lead to enhanced growth and tolerance to multiple stresses. The latter work has led to initiatives for use of plants as models to study heritable human diseases where rarity of alleles at the population level and lethality at the molecular level precludes use of animal model systems.