Clone of Sulfur metabolism

Sulfur is one of the most abundant macronutrients for plants. Approximately 1 % of the total dry weight of a plant consists of sulfur. Plants take up oxidized sulfur in form of sulfate via the roots and are able to reduce and incorporate sulfur into the proteinogenic amino acid cysteine in leaves. Consequently, plants are key players in the global sulfur cycle and essential for humans who are unable to de novo incorporate sulfur into methionine or cysteine.

Cysteine contains a redox-active thiol group, which defines cysteine as a hotspot of protein-modification and regulation in response to diverse environmental stimuli impinging on the formation of reactive oxygen species (ROS). Furthermore, cysteine is the precursor of the redox-buffer glutathione and has been recently shown to stimulate the synthesis of the stress-related phytohormone abscisic acid (ABA).