Molecular and physiological aspects of urea transport in higher plants

Urea is ubiquitous in natural environments and serves as a readily available nitrogen (N)-source for the growth of many organisms, including plants. It is synthesized during the degradation of amino acids and purines, and is accumulated in source tissues such as senescing leaves and germinating seeds, which remobilize N to sustain growth in metabolic sinks. Urea transporters from bacteria and animals have been extensively cloned and...