Abstract
BACKGROUND: Arabidopsis protein disulfide isomerase 1 (AtPDI1) has been demonstrated to have disulfide isomerase activity and to be involved in the stress response. However, whether the anti-stress function is directly related to the activities of thiol-disulfide exchange remains to be elucidated. RESULTS: In the present study, encoding sequences of AtPDI1 of wild-type (WT) and double-cysteine-mutants were transformed into an AtPDI1 knockdown Arabidopsis line (pdi), and homozygous transgenic plants named pdi-AtPDI1, pdi-AtPDI1(m1) and pdi-AtPDI1(m2) were obtained. Compared with the WT and pdi-AtPDI1, the respective germination ratios of pdi-AtPDI1(m1) and pdi-AtPDI1(m2) were significantly lower under abiotic stresses and exogenous ABA treatment, whereas the highest germination rate was obtained with AtPDI1 overexpression in the WT (WT- AtPDI1). The root length among different lines was consistent with the germination rate; a higher germination rate was observed with a longer root length. When seedlings were treated with salt, drought, cold and high temperature stresses, pdi-AtPDI1(m1), pdi-AtPDI1(m2) and pdi displayed lower survival rates than WT and AtPDI1 overexpression plants. The transcriptional levels of ABA-responsive genes and genes encoding ROS-quenching enzymes were lower in pdi-AtPDI1(m1) and pdi-AtPDI1(m2) than in pdi-AtPDI1. CONCLUSION: Taken together, these results clearly suggest that the anti-stress function of AtPDI1 is directly related to the activity of disulfide isomerase.