Regulation of root weight ratio is mediated by sucrose: Opinion

The role of sucrose in controlling RWR is exercised in both short term (substrate, osmolyte in phloem) and long term (regulation of expression of key genes in both mature source leaves and in sinks). Sucrose is a necessary, but not a sufficient, component of the mechanisms controlling RWR, with the key role of integrating the carbon balance between source and sink under the influence of a variable environment.