ABA transport and transporters.

Abscisic acid (ABA) metabolism, perception, and transport form a triptych allowing higher plants to use ABA as a signaling molecule. The molecular bases of ABA metabolism are now well described and, over the past few years, several ABA receptors have been discovered. Although ABA transport has long been demonstrated in planta, the first breakthroughs in identifying plasma membrane-localized ABA transporters came in 2010, with the identification of two ATP-binding cassette (ABC) proteins. More recently, two ABA transporters in the nitrate transporter 1/peptide transporter (NRT1/PTR) family have been identified. In this review, we discuss the role of these different ABA transporters and examine the scientific impact of their identification. Given that the NRT1/PTR family is involved in the transport of nitrogen (N) compounds, further work should determine whether an interaction between ABA and N signaling or nutrition occurs.