Li, Wing-Yen Francisca , Lam, Hon-Ming .
Ectopic Expression of a Novel Mitochondria-localized Purple Acid Phosphatase Alleviates Oxidative Stress Induced by Salinity and Drought Treatments.
The main biochemical function of purple acid phosphatases (PAPs) was believed to catalyze the hydrolysis of orthophosphate monoesters. However, there are also evidences suggesting that some PAPs may also involve in redox reactions. We cloned a novel soybean PAP gene (GmPAP3) that is induced by NaCl (salinity), PEG (drought), and Paraquat (oxidative) treatments but not by phosphorus starvation. Using confocal microscopic and immuno-histochemical approaches, the GmPAP3 protein product was found to be localized in mitochondria. It is well known that abiotic stresses such as salinity and drought may cause oxidative damage to organelle membranes due to accumulation of reactive oxygen species (ROS); and mitochondrion is one of the major sites for the production of ROS, as well as a prime target of ROS toxicity. The inducibility of GmPAP3 gene expression by salinity, dehydration and oxidative stresses; and the mitochondrial localization of GmPAP3 prompt us to further investigate the possible physiological roles of GmPAP3 under oxidative stress. When tobacco BY-2 cells were subjected to salinity and drought stresses, ectopic expression of GmPAP3 phenocopied the effects of the antioxidant ascorbic acid by (1) increasing the percentage of cells with intact mitochondria; (2) reducing the percentage of dead cells; and (3) reducing the accumulation of ROS. Ectopic expression of GmPAP3 in transgenic Arabidopsis thaliana led to a better root growth and less lipid peroxidation when the plants were subjected to salt, dehydration and oxidative treatments. In summary, this report provides the first evidence to show the existence of a mitochondrial localized plant PAP that can alleviate oxidative stress by reducing the accumulation of ROS. This research was supported by the HK RGC Earmarked Grant (CUHK-4434/04M to H.-M.L.) and and a grant from the University Grants committee of the Hong Kong Special Administrative Region (Projecct No. [AoE/B-07/99]).
Log in to add this item to your schedule
1 - The Chinese University of Hong Kong, Biology Department
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM