Many proteins are regulated by post-translational modifications, such as the reversible covalent attachment of ubiquitin and ubiquitin-like proteins in eukaryotes (Kerscher et al, 2006). Post-translational modification of proteins by the SUMO protein family is involved in diverse cellular processes, including development, hormonal responses, and biotic and abiotic stress signaling (Park et al, 2011). SUMO modification can modulate protein-protein interactions, intracellular localization or the activities of the protein (Gareau and Lima, 2010). Sumoylation occurs through a series of biochemical steps similar to ubiquitylation (Kerscher et al, 2006). The SUMO conjugation to substrates occurs through sequential enzyme action, including SUMO activating enzyme (E1), SUMO conjugating enzyme (E2) and SUMO ligase (E3). Many SUMO-modified proteins identified contain ψKX (D/E) consensus motifs (ψ, Large hydrophobic amino acid; K, Acceptor lysine; X, Any amino acid; D/E, aspartate or glutamate) (Rodriguez et al, 2001).