ABA Transport by ABCG Transporter Proteins

Abstract

The superfamily of ATP-binding cassette (ABC) transporters is one of the most abundant protein families in nature. These transporters are broadly conserved from prokaryotes to higher eukaryotes, and most of them transport various metabolites and signalling molecules in an ATP-dependent manner. Plant genomes in particular have large ABC families of more than one hundred genes, implying that some ABC transporters have important functions in plant-specific development or environmental responses. Hormones are typically regulated at the site of biosynthesis and during transport to their site of action. ABC transporters were recently reported to be involved in the transport of phytohormones, of which abscisic acid (ABA) is one of the best-studied and considered to be a plant stress hormone. This chapter describes ABC transporters whose functions are related to ABA transport and associated responses.