Regulation of sulfur metabolism in C4 plants

Sulfur is an essential macro-nutrient for the proper physiological functioning of plants and often a limiting nutrient for C4 crops. Interestingly, in C4 plants, which include maize and other agriculturally relevant species, sulfur metabolism shows a distinct cellular differentiation in the leaf with sulfate assimilation localized in the bundle sheath and not in the mesophyll. This cellular differentiation is not present in C3 plants. It remains elusive how sulfur metabolism is regulated in C4 plants and responds to changes in sulfur supply. Through manipulation of the plant’s sulfur status, the proposed project aims at investigating the consequences of being a C4 plant for the regulation of sulfur metabolism at both the organ and the leaf-tissue level. In addition, the consequences of being a C4 plant for the function of sulfur in adaptation to stress conditions will be assessed. Both the C4 plant maize (Zea mays) and species from the genus Panicum will be studied. The Panicum genus contains multiple evolutionary-related C3 and C4 plants as well as C3/C4-intermediates. Assessing the regulation of sulfur metabolism in an evolutionary gradient of plants within the same genus will provide important insight into fundamental differences of sulfur metabolism that can be attributed to being a C3 or C4 plant. With this project we aim to improve our understanding of the consequences of being a C4 plant for sulfur nutrition in order to improve sulfur fertilizer levels for C4 plants and to inform breeders on possible breeding targets for efficient sulfur uptake and use.