The TPR and J-domain containing proteins DJC31 and DJC62 are involved in abiotic stress response in Arabidopsis thaliana.

Molecular chaperones play an important role during the response to different stresses. Since plants are sessile organisms, they need to be able to adapt quickly to different conditions. To do so, plants possess a complex chaperone machinery, composed of HSP70, HSP90, J-proteins and other factors. In this study we characterized DJC31 and DJC62, two J-proteins that additionally carry clamp type tetratricopeptide repeat domains. Using cell fractionation and self-assembly GFP, we could show that both proteins are attached to the cytosolic side of the endoplasmic reticulum membrane. Moreover, an interaction with cytosolic HSP70 and HSP90 could be shown by bimolecular fluorescence complementation. Knockout of both, DJC31 and DJC62 caused severe defects in growth and development, which affected almost all organs. Furthermore, it could be shown that the double mutant is more sensitive to osmotic stress and treatment with abscisic acid, but surprisingly exhibited enhanced tolerance to drought. Taken together, these findings indicate that DJC31 and DJC62 might be acting as important regulators of chaperone dependent signalling pathways involved in plant development and stress response.