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

Transgenic canola [Brassica napus.L] plants expressing the bacterial catalase katE in the chloroplasts were obtained by the Agrobacterium-mediated transformation method. Resistance and susceptibility of the transgenic canola plants were evaluated against the airborne pathogenic fungi, Peronospora parasitica causing downy mildew and Erysiphe polygon causing powdery mildew under artificial infection in the greenhouse. The bioassays of the transgenic plants demonstrated that the growth of both fungi and the development of disease incidence were significantly inhibited in the leaves of the transgenic canola plants compared 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 bacterial catalase to the downy mildew and powdery mildew pathogens

Genetic markers associated with salt tolerance in canola [Brassica napus L.]

This study aimed at elucidating the genetic variation between five selected canola cultivars grown under Egyptian environment for salt tolerance. Seedlings from three local and two German cultivars were subjected to salt stress for two weeks. Plant growth, leaf osmotic adjustment, peroxidase isozyme, protein banding patterns and RAPD analyses were performed. Salt stress decreased leaf osmotic potential in all cultivars. The results showed that the cultivar Masrri-L16 can maintain higher osmotic potential of the cells than the other cultivars, leading to enhancement of the ability to tolerate salt stress. Salt stress induces a new peroxidase bands and increases the band intensity, indicating the protective role of peroxidase enzyme. The genetic polymorphism between the cultivars was detected by protein and RAPD analyses. In total three [21.4%] and 78 [52%] polymorphic bands were detected for protein and RAPD, respectively. The comparison between the two protocols revealed that the latter gave more markers and more conclusive results. These molecular markers were sufficient to distinguish among five canola genotypes. The genotype-specific markers represent 12.3% of the total markers detected by both analyses, 94.7% of them were RAPD markers. Thirteen RAPD markers may be considered as markers for salt tolerance in the cultivar Masrri-L11 and five markers for the cultivar Masrri-L16. These markers can be verified as being RAPD markers associated with salt tolerance in the two canola genotypes that help in marker-assisted selection breeding programs