ABC Proteins and Other Transporters in Lotus japonicus and Glycine max

Abstract

Legume plants establish a symbiosis with nitrogen-fixing bacteria called rhizobia to gain nitrogen nutrients directly from atmospheric N2 via symbiotic nitrogen fixation. This process annually provides approximately 33–46 million tons of fixed nitrogen in agricultural systems. For the establishment and maintenance of symbiotic nitrogen fixation a number of proteins, ions, and metabolites including fixed-nitrogen and photosynthetic products are exchanged between host plants and rhizobia across several membranes by a variety of transporters of both host plants and rhizobia. Many research groups have so far identified various enzymes and transporter proteins involved in the symbiosis over several decades. In this chapter we review the current knowledge on ABC proteins in legumes, especially related to symbiotic nitrogen fixation in determinate nodules representatively formed in Glycine max and Lotus japonicus. We also give an overview of other plant transporters involved in symbiotic nitrogen fixation in these legume plants.