Our work on the Yellow Stripe1 Like (YSL) family started with cloning of the maize Yellow stripe1 (ZmYS1) gene. YS1 action is the primary route by which roots of grasses take up iron from the soil. The grasses, a group that includes most of the world’s staple grains (e.g. rice, wheat and corn), use a chelation strategy for primary iron uptake. In response to iron starvation, grasses secrete phytosiderophores (PS): non-proteinogenic amino acid derivatives of the mugineic acid (MA) acid family that form stable Fe(III) chelates. This accomplishes solubilization of the otherwise nearly insoluble soil iron. ZmYS1 is responsible for moving Fe(III)-PS complexes from the soil into root cells, thus accomplishing primary iron uptake.

Most plant species do not use this phytosiderophore-mediated uptake system. Only grasses make and use phytosiderophores. Non-grass species use a ‘acidification/reduction’ strategy to accomplish iron solubilization and uptake.