Abstract- I have developed a novel E.coli based directed evolution system to evolve Ribulose-1,5 -bisphosphate carboxylase/oxygenase (Rubisco), the rate-limiting enzyme in the Calvin Cycle of photosynthetic organisms. Some of the red type Rubisco found in algae and proteobacteria have a higher affinity for CO₂ compared to green type Rubisco. So, I developed the red type Rubisco from proteobacterial Rhodobacter sphaeroides (Rs) as a model system for directed evolution, a method that mimics the natural evolution process. Four Rs Rubisco mutants with improved protein biogenesis, substrate turnover rate and substrate affinity have been identified through the directed evolution study. One mutant that showed a 1.8 times higher turnover rate was transplanted into tobacco via chloroplast biotechnology to test for possible improvements in planta. The growth phenotype of this line was compared to wild-type tobacco and other transgenic lines described in Gunn et.al (2020): significant improvements in plant photosynthesis and growth were observed when grown at ambient and high CO₂ conditions. In my seminar, I will present the results of the in vitro and in planta biochemical and growth analysis of the mutants.

Reference:

Gunn, L.H., Avila, E.M., Birch, R., Whitney, S.M., 2020. The dependency of red Rubisco on its cognate activase for enhancing plant photosynthesis and growth. PNAS. https://doi.org/10.1073/pnas.2011641117

Biography - I obtained my Bachelor of Science (Biology) degree in China, then came to Australia to pursue my Master degree, and continued in Plant Sciences as I commenced my PhD in 2017 in the Whitney lab. As part of the ARC Centre of Excellence for Translational Photosynthesis, my focus has been to work on red Rubisco directed evolution and its translational studies in planta, with the ultimate aim of trying to improve the photosynthetic performance of important crop plants so as to improve crop yield.