MSSE Thesis Defense: Funke Okunrinboye, "Genome-scale Metabolic Flux Analyses in Plant Systems"
Wednesday, August 11, 2021
Genome-scale Metabolic Flux Analyses in Plant Systems
Advisor: Dr. Ganesh Sriram
Committee member: Dr. Jeffrey W. Herrmann
Committee member: Dr. Srinivasa Raghavan
Plants are essential in food, energy, pharmaceutical and agricultural industries, thus, making these systems targets for yield optimizations. We study the optimization of Populus trichocarpa (Poplar) leaf biomass (BM), which is used in paper and bio-renewable fuel synthesis, making poplar biomass an interesting metabolic engineering target. Similarly, we study Zea mays (maize), a source of starch macronutrients, and zein proteins, a source of amino acids.
These were done using flux balance and variability analyses (FBA and FVA), with Constraint-Based Reconstruction and Analysis toolbox in MATLAB. First, we validate glutamine as the most optimum single amino acid cargo and perform FVA nodal rigidity studies to obtain the flux ranges of the RuBisCO and photon fluxes for the four optimum amino acids: Arginine, glutamine, asparagine, and glycine.
From our FVA nodal rigidity studies the flux ranges of [photon flux, RuBisCO flux] for arginine, glutamine, asparagine, and glycine were [0, 921.6011] and [1000, 397.5579]; [0, 581.7792] and [155.3076, 1000]; [0, 1000] and [155.8936, 1000]; [0, 423.6422] and [155.8936, 1000] respectively in the synthesis of 1.29 mol leaf BM per mol BSP.
We further observe a compensating trend between carbon rich amino acid (with the highest C:N ratio) tryptophan and nitrogen rich amino acid (highest N:C ratio) arginine in duo-amino acid transport scenarios for leaf BM maximization. In maize, serine was the most optimal transport amino acid to the endosperm for starch and zein protein synthesis in both WT and PPDK mutant models, with a starch synthesis flux of 2.45 moles and a max zein protein flux of 3.83 moles per mole of sucrose and per mole of serine in WT; and a starch synthesis flux of 2.84 moles and a max zein protein flux of 3.62 moles per mole of sucrose and per mole of serine in the PPDK mutant.