Possesses transactivation activity in yeast cells (Ref.1). Involved in the regulation of stomatal aperture. May modulate the expression of genes that control stomata opening during heat shock or drought stress (PubMed:25002225). S-ubiquitinyl-[E2 ubiquitin-conjugating enzyme]-L-cysteine + [acceptor protein]-L-lysine = [E2 ubiquitin-conjugating enzyme]-L-cysteine + N(6)-ubiquitinyl-[acceptor protein]-L-lysine. Protein modification; protein ubiquitination. Induced by salicylic acid (SA), ethylene and infection with the rice blast fungal pathogen Magnaporthe oryzae (Ref.1). Induced by abscisic acid (ABA) and heat shock in leaves (PubMed:25002225). Decreased relative stomata aperture under normal growth conditions. Truncated N-terminus.