Global population is estimated to reach nine billion by 2050. Yields of important crop plants, like rice, wheat, corn and soybean, using current technologies will fall grossly short of demand, and innovative strategies to increase plant productivity are urgently needed.  Plants using C4 photosynthetic biochemistry (e.g. corn) evolved from species using C3 photosynthesis (e.g. rice), and are Nature’s supercharged species, showing higher water and nitrogen use efficiencies and greater photosynthetic capacities in hot, dry, high light environments.  Identification of the molecular mechanisms underlying the evolution of C4 plants from their C3 ancestors will enable novel approaches to meet future demands for food, fodder and fuel.

Professor Ludwig’s research encompasses the cell and molecular biology, molecular genetics and evolution of photosynthetic pathways. The overall aim of her work is to understand how C4 plants evolved the ability to concentrate CO2 in their leaves, which resulted in their superior photosynthetic traits in habitats that are unfavourable to C3 species. This knowledge is critical for developing ground-breaking strategies to supercharge C3 crop plants, thereby increasing yields and extending arable environments.

Plants require sunlight, water and atmospheric CO2 to carry out photosynthesis. Depending on its CO2 assimilation biochemistry, a plant is described as a C3, a C4 or a Crassulacean Acid Metabolism (CAM) plant. C4 and CAM plants evolved from C3 species, and this process has occurred multiple times in different plant families. However, the molecular events essential for the evolution of C4 and CAM plants from their C3 ancestors have not been elucidated.

Professor Ludwig’ group uses closely related species within the dicotyledonous genus Flaveria and the monocotyledonous tribe Neurachninae that demonstrate C3, C4 or C3-C4 intermediate-type photosynthesis to comparatively examine the anatomical and molecular changes that have occurred during the evolution of C4 plants.  Importantly, the Neurachninae is the only known grass lineage with closely related C3, C3-C4 and C4 species, and these species are found only in Australia. Use of this plant group as a model for C4 evolution is a significant step forward in creating supercharged plants, as the major crop species are grasses.

The research group uses a combination of cell and molecular biology and genetics techniques to investigate the above research questions. They look at the products of gene expression using in situ localisation methods that involve microscopy with antibodies and nucleic acid probes. They investigate the genes and the sequences controlling when, where and how they are active using recombinant DNA technology, quantitative reverse transcription PCR, RNA-Seq, and immunoblotting techniques. They use transgenic technologies to examine the intracellular locations of proteins, functions of gene products, gene control regions, and to investigate the effects on plant productivity when a plant makes more or less of a particular photosynthetic protein than wild type plants.


  • Professor Rowan Sage, University of Toronto
  • Associate Professor Tammy Sage, University of Toronto
  • Professor Peter Westhoff, Heinrich Heine Universität Düsseldorf
  • Professor Andreas Weber, Heinrich Heine Universität Düsseldorf
  • Dr John Lunn, Max Planck Institute of Molecular Plant Physiology