“…In plants, only a few in vivo substrates have been identified, such as cadmium and auxin for ABCG36 (PDR8), 2,4-dichlorophenoxy acetic acid for ABCG37 (PDR9), and abscisic acid for ABCG40 (PDR12; Kim et al, 2007;Strader and Bartel, 2009;Kang et al, 2010). However, there is some evidence that plant PDRs may transport a variety of secondary metabolites, including antimicrobial and antifungal compounds, as well as xenobiotics and heavy metals (Martinoia et al, 2002;Campbell et al, 2003;Moons, 2003;Ducos et al, 2005;Stukkens et al, 2005;Ito and Gray, 2006;Kobae et al, 2006;Stein et al, 2006;Krattinger et al, 2009).…”