Research area 3
stomata regulation via cysteine synthesis
Molecular mechanisms of drought resistance have become a major target of environmental stress research in the department (see research by M. Wirtz). Earlier reports had suggested sulfate as a signal during early onset of soil water deficit, even preceeding ABA in the vasculature. In cooperation with the team of H. Rennenberg (Freiburg) it was shown that Arabidopsis and poplar indeed can close stomata by sulfate during onset of drought. This was followed up by mechanistic investigations focusing on a set of Arabidopsis mutants in sulfur metabolism and transport as well as ABA synthesis and signaling. These studies surprisingly revealed that not sulfate, but cysteine synthesized in chloroplasts of guard cells is prerequisite for de-novo synthesis of ABA for stomatal closure. Using live cell imaging with the Abaleon ABA sensor we showed that indeed ABA concentrations increase specifically after sulfate feeding and that cell-autonomous synthesis is sufficient for closure. Arabidopsis mutants lacking cysteine synthesis in plastids are consequently drought resistant. This discovery contributes to the multi-layer system of water deficit sensing to optimize plant growth and survival.
Figure 1
Molecular mechanisms of drought resistance have become a major target of environmental stress research in the department (see research by M. Wirtz). Earlier reports had suggested sulfate as a signal during early onset of soil water deficit, even preceeding ABA in the vasculature. In cooperation with the team of H. Rennenberg (Freiburg) it was shown that Arabidopsis and poplar indeed can close stomata by sulfate during onset of drought. This was followed up by mechanistic investigations focusing on a set of Arabidopsis mutants in sulfur metabolism and transport as well as ABA synthesis and signaling. These studies surprisingly revealed that not sulfate, but cysteine synthesized in chloroplasts of guard cells is prerequisite for de-novo synthesis of ABA for stomatal closure. Using live cell imaging with the Abaleon ABA sensor we showed that indeed ABA concentrations increase specifically after sulfate feeding and that cell-autonomous synthesis is sufficient for closure. Arabidopsis mutants lacking cysteine synthesis in plastids are consequently drought resistant. This discovery contributes to the multi-layer system of water deficit sensing to optimize plant growth and survival.
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