Overproduction of superoxide dismutase and catalase confers cassava resistance to Tetranychus cinnabarinus

To explore the role of protective enzymes in cassava (Manihot esculenta Crantz) resistance to mites, transgenic cassava lines overproducing copper/zinc superoxide dismutase (MeCu/ZnSOD) and catalase (MeCAT1) were used to evaluate and molecularly confirm cassava resistance to Tetranychus cinnabarinus. Laboratory evaluation demonstrated that, compared with the control cultivar TMS60444 (wild type, WT), the survival, reproduction, development and activities of SOD and CAT in T. cinnabarinus feeding on transgenic cassava lines SC2, SC4, and SC11 significantly inhibited. Furthermore, the activities of SOD and CAT in transgenic cassava lines SC2, SC4, and SC11 damaged by T. cinnabarinus significantly increased. These findings were similar to the results in the mite-resistant cassava cultivars. Besides, field evaluation indicated that the transgenic cassava lines SC2, SC4, and SC11 were slightly damaged as the highly mite-resistant control C1115, while the highly mite-susceptible WT was severely damaged by T. cinnabarinus. Laboratory and field evaluation demonstrated that transgenic cassava lines were resistant to T. cinnabarinus, which directly confirmed that the increase in SOD and CAT activities was positively related to cassava resistance to T. cinnabarinus. These results will help in understanding the antioxidant defense responses in the cassava-mite interaction and molecular breeding of mite-resistant cassava for effective pest control.