Abstract
Active oxygen species (AOS) are important signal molecules that regulate many cellular processes including environmental stress response. In higher plants, ascorbate peroxidase (APX) is thought to be one of the key enzymes maintaining the homeostasis of cellular AOS. Previously, we have established cytosolic APX-suppressed tobacco BY-2 cell lines, which showed altered cellular redox status. In this study, we have investigated the effect of altered cellular redox status on cell ability against various environmental stress conditions using transformed BY-2 and Arabidopsis suspension cell lines. The constitutively elevated cellular AOS level resulting from the suppression of cytosolic APX caused significant tolerance to different environmental stress, such as heat, salt, and H 2 O 2 . Expressed gene analysis of the cell using RT-PCR indicated some stress responsible genes, such as HSP, NDPK, NPK-1, were up-regulated even under normal growth conditions. Otherwise, cytosolic APX-overexpressed Arabidopsis cell lines were susceptible to heat stress.
