Transgenic canola plants over-expressing bacterial catalase exhibit enhanced resistance to Peronospora parasitica and Erysiphe polygoni

Transgenic canola (Brassica napus.L) plants express ing the bacterial catalase katE in the chloroplasts were obtained by the Agrobacterium-med iated transformation method. Resistance and susceptibility of the transgenic canola plants were evaluated against the airborne pathogenic fungi, Peronospora parasitica causing downy mildew and Ery siphe polygon causing powdery mildew under artificial infection in the greenhouse. The b ioassays of the transgenic plants demonstrated that the growth of both fungi and the development o f disease incidence were significantly inhibited in the leaves of the transgenic canola plants compa red to controls. Chemical analyses of the transgenic plants revealed constitutive expression of the enzymes catalase, peroxidase and polyphenoloxidase as well as higher levels of free polyamines i. e. putrescine, spermidine and spermine compared with the control plants. Together , these data indicate an enhanced resistance of the transgenic canola plants expressing the bacteri al catalase to the downy mildew and powdery mildew pathogens.