Respiration in plants is a foundational metabolic process. Over the lifecycle of a plant, respiration will release half the carbon it has captured by photosynthesis back to the atmosphere as CO2 and fuel biosynthetic processes for the maintenance and growth of cells. Taking an engineering approach to this central process promises the opportunity to reach optimal respiratory behaviour, tuned to different environments, in order to alter the composition of plant biomass. To meet this goal there are still fundamental aspects of the flux of respiratory-linked processes in plants that we need to understand. We have been focusing on both inputs and outputs of respiration and how they impact plants. The inputs to respiration range across the major classes of organic and amino acids and beyond. We have been using a combination of genetics, biochemistry, transport and flux measurements to determine the membrane carriers that transport different substrates in and out of mitochondria for respiration and oxidative phosphorylation and how amino acids can influence the rates of respiratory processes. One of the major outputs of respiration is ATP and one of its major uses is in protein homeostasis, enabling the synthesis and degradation of proteins. We have been using advances in stable isotope labelling to measure the individual synthesis and degradation rates of plant proteins to learn about the use of ATP in maintaining cell function and in building the protein composition of plant products. Our fundamental work is in model plants like Arabidopsis, and applications are made in determining how protein synthesis and degradation support final protein composition in cereal grains like wheat.
Bio: Harvey Millar completed his PhD at the Australian National University in Canberra in 1997, supervised by David Day, before undertaking a postdoctoral fellowship at the University of Oxford UK in the laboratory of Chris Leaver (1997-2000). He has held a series of research fellowships and leadership roles in research centres at the University of Western Australia (UWA) since 2000. He is currently Director of the ARC Centre of Excellence in Plant Energy Biology based at UWA.
Recent relevant publications:
O'Leary BM, Oh GGK, Lee CP, Millar AH. (2020) Metabolite Regulatory Interactions Control Plant Respiratory Metabolism via Target of Rapamycin (TOR) Kinase Activation. Plant Cell. 32:666-682.
Lee CP, Elsässer M, Fuchs P, Fenske R, Schwarzländer M, Millar AH (2021) The versatility of plant organic acid metabolism in leaves is underpinned by mitochondrial malate–citrate exchange. Plant Cell. 33:3700-3720
Le XH, Lee CP, Millar AH (2021) The mitochondrial pyruvate carrier (MPC) complex is one of three pyruvate-supplying pathways that sustain Arabidopsis respiratory metabolism. Plant Cell 33:2776-2793
Li L, Duncan O, Ganguly DR, Lee CP, Crisp PA, Wijerathna-Yapa A, Salih K, Trösch J, Pogson BJ, Millar AH. (2022) Enzymes degraded under high light maintain proteostasis by transcriptional regulation in Arabidopsis. Proc Natl Acad Sci U S A. 2022 119(20):e2121362119.
Cao H, Duncan O, Millar AH (2021) Protein turnover in the developing Triticum aestivum grain. New Phytologist 233:1188-1201
