E3 ubiquitin-protein ligase that promotes osmotic stress responses. Regulates negatively drought-mediated control of early seedling development, probably by influencing proline content, water loss, membrane ion leakage and the expression of dehydration stress-related genes (e.g. RAB18, RD29A, RD29B, AOX1A, ERD15, ERD1, COR15A, P5CS1 and P5CR). 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. Expressed in seedlings and in flowers. In seedlings, especially present in the vascular system. In flowers, observed in sepals, anthers of stamen, and pollen. Repressed by drought and osmotic (e.g. 400 mM mannitol) stresses. Reduced sensitivity to osmotic stress during early seedling development. Increased proline accumulation and higher expression of stress-related genes (e.g. RAB18, RD29A, RD29B, AOX1A, ERD15, ERD1, COR15A, P5CS1 and P5CR) under drought stress.