Transporters involved in mineral nutrient uptake in rice.

One of the most important roles of plant roots is to take up essential mineral nutrients from the soil for use in plant growth and development. The uptake of mineral elements is mediated by various transporters belonging to different transporter families. Here we reviewed transporters for the uptake of macronutrients and micronutrients identified in rice, an important staple food for half of the world's population. Rice roots are characterized by having two Casparian strips on the exodermis and endodermis and by the formation of aerenchyma in the mature root zone. This distinct anatomical structure dictates that a pair of influx and efflux transporters at both the exodermis and endodermis is required for the radial transport of a mineral element from the soil solution to the stele. Some transporters showing polar localization at the distal and proximal sides of the exodermis and endodermis have been identified for silicon and manganese, forming an efficient uptake system. However, transporters for the uptake of most mineral elements remain to be identified.