Suc transporter phylogenetic tree. Suc transporter protein sequences of Arabidopsis (AtSUC1 [At1g71880], AtSUC2 [At1g22710], AtSUT2/AtSUC3 [At2g02860], AtSUT4 [At1g09960], AtSUC5 [At1g71890], AtSUC6 [At5g43610], AtSUC7 [At1g66570], AtSUC8 [At2g14670], and AtSUC9 [At5g06170]), rice (OsSUT1 [Os03g07480], OsSUT2 [Os12g44380], OsSUT3 [Os10g26740], OsSUT4 [Os02g58080], and OsSUT5 [Os02g36700]), sugarcane (ShSUT1 [AAV41028]), and barley (HvSUT1 [CAJ20123]) were aligned using ClustalX followed by neighbor-joining analysis in PAUP 4.0 to create the tree. The phylogram was rooted using SpSUT1 (Reinders and Ward, 2001) from Schizosaccharomyces pombe as the outgroup. The assignment of type I, II, and III follows the nomenclature in Aoki et al. (2003).