The invention provides genetic constructs which comprise a senescence-specific promoter operably linked to at least one coding sequence, which encodes at least one polypeptide having phosphoenolpyruvate carboxykinase (PCK) activity and/or pyruvate orthophosphate dikinase (PPDK) activity. The constructs have the ability to cause, in transgenic plants, remobilisation of nitrogen during leaf senescence, such that nitrogen can be transported from the leaves to other regions of the plants. The invention provides plant cells and plants transformed with such constructs, methods of producing transgenic plants, and methods of increasing the rate of nitrogen remobilisation and growth rate in senescent plants. The invention also provides harvested plant leaves, such as tobacco leaves, that have been transformed with the genetic constructs, and to smoking articles comprising such harvested plant leaves.
