Source-sink and phytohormone-dependent regulation of tiller formation versus nodal rooting

Kai Eggert, Markus Meier, Christine Bethmann

Nutrient uptake, yield formation and stress tolerance in wheat strongly rely on an efficient root system that is able to support the new formation of shoot organs. Cereals like wheat produce with every new tiler also new nodal roots that are supposed to adequately supply the newly formed above-ground biomass with water and nutrients. However, both organs, tillers and nodal roots, also compete for nutrients and assimilates, raising the question which exogenous and endogenous factors control the balance of tiller versus nodal root formation. In cooperation with a private plant breeder we tackle this question by screening for contrasting wheat cultivars with different ratios of tiller versus nodal roots to investigate the role of phytohormones and assimilate partitioning in organ developement and finally yield formation