Abstract -C₄ photosynthesis involves a number of biochemical and anatomical traits that significantly improve plant productivity under conditions that reduce the efficiency of C₃ photosynthesis. During my PhD, I explored how evolution of the three classical biochemical types of C₄ photosynthesis (NADP-ME, NAD-ME and PCK types) has affected the functions and properties of mitochondria. Mitochondria in C₄ NAD-ME and PCK types play a direct role in decarboxylation of metabolites for C₄ photosynthesis. Mitochondria in C₄ PCK type also provide ATP for C₄ metabolism, although this role for ATP provision is not seen in NAD-ME type. This has led to an increase in mitochondrial abundance/size and associated enzymatic capacity, changes in mitochondrial ultrastructure, altered roles of mitochondria in cellular carbon metabolism, and shifted preferences of substrates by mitochondria in the NAD-ME and PCK types. By contrast, these changes in mitochondrial properties are absent in the C₄ NADP-ME type and C₃ leaves, where mitochondria play no direct role in photosynthesis. This work provides a foundation for future mitochondrial research in key areas central to the engineering of the C₄ pathway into C₃ plants and to the understanding of variation in rates of C₄ dark respiration.

Biography -During her undergraduate degree (BSc) at ANU (2014-2016), Yuzhen carried out two summer research projects at the Research School of Biology – one working with Owen Atkin on leaf respiration and the other working with Susanne von Caemmerer on C₄ photosynthesis. Later in 2017, merging what she had learnt from these two summer projects, Yuzhen went on to do an Honours degree investigating the roles of mitochondria in C₄ plants in the Atkin Lab. It seems that Yuzhen has not had enough of C₄ respiration; immediately after her Honours, Yuzhen began her PhD project in the Atkin Lab on the same topic. She focused on advancing the mechanistic understandings of mitochondria in C₄ plants using novel three-dimensional microscopy and high-throughput metabolomic approaches.

Roses are red. Violets are blue. Yuzhen likes C₄. Hope you do too (after her talk).