Mineral nutrition in closely related C3 and C4 plants
C4 photosynthesis relies on a cell-specific localization of enzymes involved in CO2 assimilation in bundle sheath cells or mesophyll cells. Interestingly, enzymes of nitrogen and sulfur assimilation are also differentially localized in maize and many other C4 species. While enzymes for nitrate reduction are present exclusively in the mesophyll, sulfate assimilation is specific to bundle sheath. This localization, however, could not be confirmed in C4 species of the genus Flaveria and it thus seems to be limited to C4 monocots. However, recently we found the sulfate assimilation pathway to be coordinately enriched in bundle sheath cells of Arabidopsis, opening new questions about the significance of such cell-specific localization of the pathway. In addition, within the genus Flaveria we observed a gradient with higher expression of genes for sulfate reduction and higher accumulation of reduced sulfur metabolites in C4 species than in C3 species. We are therefore interested in the the following questions:
- What are the general consequences of C4 photosynthesis for nutrient homeostasis?
- What is the role of the spatial distribution of enzymes of nitrate and sulfate assimilation in C4 leaves for N and
S homeostasis and use efficiency?
- What are the mechanisms underlying differences in nutrient uptake and partitioning among C3 and C4 plants?
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