Consequence of decrease in function of SAL1/RON1 gene in response to Aminoteriazole-induced oxidative stress in Arabidopsis mutant plants ron1-1

The growth and development of plants under biotic and abiotic stresses is always accompanied with accumulation of various reactive oxygen species (ROS) molecules. Higher levels of ROS can be harmful leading to oxidative stress-induced leaf death. In addition, chemical materials such as Aminoteriazole (AT) can cause oxidative stress by suppression of catalase activity. RON1/SAL1 gene is one of the environmental stress responsive genes in Arabidopsis encoding the polyphosphate 1-phosphatase enzyme. Most of available mutations in RON1 are accompanied with changes in their responses to various environmental stresses. To analysis the functional role of the RON1/SAL1 gene in response to oxidative stress induced by AT, several morphological, molecular and biochemical characterizations were assayed in Arabidopsis ron1-1 mutant plants, which has a point mutation in RON1/SAL1 and compared with those in wild type plants (Ler-0). The results showed a significant reduction in ron1-1 shoots, roots, and total plant weight in comparison with the wild type plants. Also, assessment of the chlorophyll content indicated a significant decrease in the mutant plants as compared with the wild types. In addition, a significant increase in ascorbate peroxidase enzyme activity in the mutant plants was detected. Also, catalase activity in mutant plants was increased in response to AT. Analysis of relative gene expression of oxidative marker genes including DEFL and sAPX in different concentrations of AT showed a significant increased in the expression of DEFL and sAPX genes in wild type plants compared to mutant plants. Therefore, probably the activity of RON1 protein caused by the ron1-1 mutation in mutant plants has been changed and this resulted in increased sensitivity to oxidative stress.