Mechanisms and control of nutrient uptake in plants.

This review is a distillation of the vast amount of physiological and molecular data on plant membrane transport, to provide a concise overview of the main processes involved in the uptake of mineral nutrients in plants. Emphasis has been placed on transport across the plasma membrane, and on the primary uptake from soil into roots, or in the case of aquatic plants, from their aqueous environment. Control of uptake has been mainly considered in terms of local effects on the rate of transport and not in terms of long-distance signaling. The general picture emerging is of a large array of membrane transporters, few of which display any strong selectivity for individual nutrients. Instead, many transporters allow low-affinity uptake of several different nutrients. These features, plus the huge number of potential transporter genes that has been revealed by sequencing of plant genomes, raise some interesting questions about their evolution and likely function.