Single cell C4 Photosynthesis: Development and Function in Terrestrial Plants

Washington State University, Pullman WA

Investigators

Abstract

Plant growth depends on assimilation of atmospheric carbon dioxide (CO2) by photosynthesis. The availability of CO2 for photosynthesis can be a limiting factor under environmental stress, including drought, saline soils and high temperatures, conditions expected to exacerbate under global warming. Certain plants, including many weeds and only a few food crops, use a type of photosynthetic mechanism called C4 which actively accumulates CO2 from the atmosphere. This confers an advantage especially under those extreme environments. The project is focused on species of C4 land plants which have a unique form of carbon acquisition, and its usage in photosynthesis. Prior to the recent discovery of this type of photosynthetic mechanism, called single-cell C4, the paradigm for C4 plants was the requirement for cooperative function of two cell types (so-called Kranz anatomy). In the single-cell C4 species, there is the unprecedented development of photosynthetic cells containing two types of chloroplasts which exist in separate compartments, one specializing in supporting active capture of atmospheric CO2 and the other in its assimilation into organic matter. Central problems to be investigated are the mechanism(s) controlling chloroplast differentiation, the development of the spatial compartmentation and the role of these compartments in photosynthesis. The general approach will include use of microscopy, molecular biology, protein identification and physiology. We expect to gain insights into an exceptional mechanism of photosynthesis, and provide new models for plant cell organization, and structural and biochemical differentiation. Due to its relative physical simplicity compared to Kranz anatomy, the single-cell mechanism could be instrumental in engineering crops, such as rice, to produce greater yields, especially under climate changes occurring with global warming. Broader impacts are expected in education through teaching and textbook information on the mechanisms of photosynthesis, through training of undergraduate and graduate students and hosting of visiting scientists.