Changes in some antioxidant enzymes activities and carotenoid content in potato plants infected by Rhizoctonia solani treated with salicylic acid

Abstract

This study was carried out to evaluate the effects of salicylic acid on chlorophyll, carotenoid and antioxidant enzymes in potato plants infected with Rhizoctonia solani under greenhouse conditions. Results showed that with increase in SA amount of chlorophyll, carotenoid contents and also activity of polyphenoloxidase increased in both control and infected plants while increases in infected plants were higher. However, activities of peroxidase and catalase enzymes decreased under the same conditions. Hence, it seems that increase in carotenoid content in infected plants treated with SA is acting as an anti-oxidant against fungi infection. The decrease in catalase and peroxidase activities in response to SA treatment will result in reactive oxygen species produced be less oxidized. The remaining ROS in plants treated with SA is probably acting as anti-fungal agents. The increase in polyphenoloxidase activity will increase the root cells walls lignifications process acting as mechanical barrier against fungal infection.