The role of long-distance signalling in plant responses to nitrate and other nutrients.

The phenotypic plasticity that plants display in response to changes in their nutrient supply requires the operation of both short- and long-range signalling pathways. Long-distance signals arising in the root can provide the shoot with an early warning of fluctuations in external nutrient concentrations, while signals in the reverse direction are needed to ensure that root physiology and development are integrated with the nutritional demands of the shoot. In this review, the focus is on recent advances in the understanding of these long-distance signalling pathways with an emphasis on nitrate nutrition, and a personal view of the key issues for future research is put forward.