08.10.2019: Ties AUSMA (Groningen): Regulation of Sulfur Metabolism in C4 Plants, HS 32.01, Institut für Biologie, Bereich für Pflanzenwissenschaften, Holteigasse 6, 17:00 Uhr.
Sulfur is an essential macronutrient for the proper physiological functioning of plants. However, its availability in soils is frequently suboptimal and limiting crop productivity. To improve sulfur fertilization and the sulfur use efficiency of crops a detailed understanding of how plants regulate sulfur homeostasis is needed. Notably, this regulation has hardly been investigated in plants that have C4 photosynthesis, despite ongoing efforts to grow more C4 plants in agriculture. C4 plants differ considerably in leaf morphology and physiology from plants that have C3 photosynthesis. Findings from C3 plants can thus not simply be extrapolated to C4 plants. Therefore, in the current research the regulation of sulfur homeostasis was studied in C4 plants. Regulation was studied by exposing plants to atmospheric hydrogen sulfide (H2S). It has been shown that C3 plants may use gaseous H2S as sulfur source for growth, which strongly alters the chemical composition of tissues. This alteration induces a downregulation in the metabolism of sulfate, taken up by the root. However, from the research it was clear that although C4 plants could use H2S as sulfur source for growth and although H2S uptake downregulated sulfate reduction, it did not downregulate sulfate uptake. Evidently, this process is differently controlled in C3 and C4 plants. Furthermore, it was apparent that in C4 plants sulfate uptake is differently linked to the uptake of other nutrients. Sulfate import in C4 plants is controlled by a transcriptional mechanism. Though the nature of this mechanism remained elusive, it was unlikely that metabolites from sulfur, nitrogen and carbon metabolism act as upstream signal compounds.