Dissecting C4 leaf biogenesis and C3 and C4 pollen development during exposure to high temperature to enable global food security

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Global agriculture is facing a time of crisis. Increasing population growth, persistent loss of arable land, increasing meat consumption and global climate change collectively threaten global food production. To maintain global food security, cereal production will have to increase 70% by 2050. Yields of major food crops - rice, wheat and corn - decline with increasing temperatures; for example, rice and wheat yields decline 10% and 3 to 4%, respectively, for every 1 °C increase in temperature above the optimal growth temperature. Efforts to maintain food security have led to major international initiatives to enhance the photosynthetic efficiency and improve crop stress tolerance. My research contributes to these efforts by developing a basic understanding of the functional development of C4 photosynthesis, the most efficient form of primary production in the biosphere, and heat stress tolerance of plant reproduction. To sustain my contribution, this proposal request funds for two projects. First, to support ongoing efforts to engineer the C4 photosynthetic pathway into our major crops such as wheat and rice, we will examine the evolutionary development of the C4 leaf structure, with the aim of identifying the genes central to the origin of organelle enrichment in cells where the carbon concentrating mechanisms resides in a C4 photosynthetic leaf. Our research should help overcome one of the main bottlenecks currently hindering C4 engineering, This effort will emphasize molecular and cellular assessment of leaf development in C3 and C4 species Atriplex pair and their hybrids and the grass subtribe Neurachninae. The Neurachninae is the only grass lineage known to contain C3, C2, and C4 species, and as such has been suggested as a model system for studies of photosynthetic pathway evolution in the grasses. Second, we will exploit recent advances in our lab in understanding the mechanisms controlling heat sterility in crops. Exposure to 32°-36 °C severely reduces pollen viability and thus seed set, particularly in canola, maize, wheat and rice. With continued climate warming, Canada’s major crops such as wheat and canola may also encounter increased incidences of pollen sterility. We have found that heat reduces pollen survival via production of reactive oxygen species and have identified a gene that confers heat tolerance by detoxifying oxidative compounds. In the proposed research, we intend to examine the role of high temperature induced protein oxidation during reproduction in major crop species in order to provide researchers with information needed to enhance heat tolerance during this critical stage of the plant life cycle.