Stress inducible cytosolic ascorbate peroxidase (Ahcapx) from Arachis hypogaea cell lines confers salinity and drought stress tolerance in transgenic tobacco

Abstract

Ascorbate peroxidase regulates toxic levels of hydrogen peroxide and catalyzes the reduction of H2O2 to water. A cDNA encoding cytosolic ascorbate peroxidase (Ahcapx) was isolated from the salt tolerant (ST) cell lines of Arachis hypogaea, that showed higher transcript level and 4.5 times higher total APX enzyme activity in the ST lines as compared to salt sensitive lines (SS). The transgenic tobacco plants overexpressing the Ahcapx gene were salinity and drought tolerant as compared to wild type (WT) plants. The transgenic plants had higher chlorophyll content and displayed enhanced germination rate under the abiotic stresses. In addition they also exhibited better photosynthetic efficiency, lower membrane damage and relatively higher values of ascorbate peroxidase activity under stress conditions. These results functionally validate a potential role of Ahcapx, as an important scavenger of reactive oxygen species useful in conferring stress tolerance in plants.