title: Combining genetic and evolutionary engineering to establish C4 metabolism in C3 plants.
abstract: To feed a world population projected to reach 9 billion people by 2050, the productivity of major crops must be increased by at least 50%. One potential route to boost the productivity of cereals is to equip them genetically with the 'supercharged' C4type of photosynthesis; however, the necessary genetic modifications are not sufficiently understood for the corresponding genetic engineering programme. In this opinion paper, we discuss a strategy to solve this problem by developing a new paradigm for plant breeding. We propose combining the bioengineering of well-understood traits with subsequent evolutionary engineering, i.e. mutagenesis and artificial selection. An existing mathematical model of C3-C4evolution is used to choose the most promising path towards this goal. Based on biomathematical simulations, we engineer Arabidopsis thaliana plants that express the central carbon-fixing enzyme Rubisco only in bundle sheath cells (Ru-BSC plants), the localization characteristic for C4plants. This modification will initially be deleterious, forcing the Ru-BSC plants into a fitness valley from where previously inaccessible adaptive steps towards C4photosynthesis become accessible through fitness-enhancing mutations. Mutagenized Ru-BSC plants are then screened for improved photosynthesis, and are expected to respond to imposed artificial selection pressures by evolving towards C4anatomy and biochemistry.
authors.affiliation: Institute of Developmental and Molecular Biology of Plants, Plant Molecular Physiology and Biotechnology Group, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany.|Institute for Computer Science, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany.|Cluster of Excellence on Plant Sciences (CEPLAS), 40225 Düsseldorf, Germany.
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Institute for Computer Science, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany.
authors.forename: David
authors.initials: D
authors.lastname: Heckmann
authors.affiliation: Institute for Computer Science, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany.|Cluster of Excellence on Plant Sciences (CEPLAS), 40225 Düsseldorf, Germany.
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Lercher
authors.affiliation: Institute of Developmental and Molecular Biology of Plants, Plant Molecular Physiology and Biotechnology Group, Heinrich Heine University, Universitätsstr. 1, 40225 Düsseldorf, Germany veronica.maurino@uni-duesseldorf.de.|Cluster of Excellence on Plant Sciences (CEPLAS), 40225 Düsseldorf, Germany.
authors.forename: Veronica G
authors.initials: VG
authors.lastname: Maurino
mesh_terms: D005075:Biological Evolution; D005818:Genetic Engineering; D010788:Photosynthesis / Q000235:genetics*; D000069600:Plant Breeding / Q000379:methods*; D012273:Ribulose-Bisphosphate Carboxylase / Q000235:genetics / Q000378:metabolism
chemical_list: D012273:Ribulose-Bisphosphate Carboxylase
keywords: Arabidopsis; C4 photosynthesis; artificial selection; biomathematical modelling; evolutionary engineering; genetic engineering; mutagenesis.