Postdoctoral Research Associate Washington University in St. Louis
Autophagy or ‘self-eating’ is a conserved and essential route for recycling intracellular constituents in eukaryotes. For plants in particular, autophagy supports robust crop performance by regulating traits such as nitrogen-use efficiency, carbon allocation, reproduction, grain fill, and protection against various environmental stresses. We are now defining the autophagic processes underlining nutrient partitioning, which are used to sustain plant fitness under nutrient stress and during rapid growth of sink tissues, by applying a comprehensive multi-omic approach with maize (Zea mays) mutants lacking the core autophagy component ATG12. Under nutrient stress caused by fixed-carbon starvation induced by darkness, leaves of atg12 plants experience dramatic changes in amino acid-, carbohydrate- and nucleotide-related metabolites, which are accompanied by a strong upregulation of catabolic processes as determined by the paired maize leaf transcriptomes and proteomes. To better understand how autophagy impacts source/sink relationships and nutrient partitioning, we are now analyzing the atg12 mutants during seed maturation and along the innate developmental gradient of a leaf from its base to tip, both of which require massive investments of fixed-carbon. The leaf proteome of atg12 mutants display a hyperaccumulation of proteins particularly in the mature sections compared to the juvenile tissue at the leaf base. Hyperaccumulating proteins within the mature leaf sections are enriched for catabolic processes such as glycolysis and β-oxidation, which may aid in the maintenance of these tissues as nutrient sources under autophagy deficient conditions. Metabolomic, transcriptomic, proteomic and ionomic analyses of developing atg12 seeds revealed pronounce transcriptional reprogramming at 8 DAP, which may contribute to the observed hyperaccumulation of metabolites and ions at 18 DAP within the endosperm. Collectively, this multi-omic approach should provide new perspectives into the adaptive role of autophagy in response to adverse conditions and its role(s) in coordinating nutrient allocation.
Coauthors: Fionn McLoughlin – Washington University in St. Louis;Richard Vierstra – Washington University in St. Louis
