Suppression of DRR1 results in the accumulation of insoluble ubiquitinated proteins,which impairs drought stress tolerance

Drought stress has detrimental effects on plants.Although the abscisic acid(ABA)-mediated drought response is well established,defensive mechanisms to cope with dehydration-induced proteotoxicity have been rarely studied.DRR1 was identified as an Arabidopsis drought-induced gene encoding an ER-localized RING-type E3 Ub ligase.Suppression of DRR1 markedly reduced tolerance to drought and proteotoxic stress without altering ABA-mediated germination and stomatal movement.Proteotoxicityand dehydration-induced insoluble ubiquitinated protein accumulation was more obvious in DRR1 loss-of-function plants than in wild-type plants.These results suggest that DRR1 is involved in an ABA-independent drought stress response possibly through the mitigation of dehydration-induced proteotoxic stress.