1983 Volume 49 Issue 3 Pages 331-337
Incorporating the exogenous DNA to potato epidermis with rubbing by a brush or cotton ball, severe destruction of hairs and their neighboring parts was observed by scanning microscope. Specific fluorescence of ethidium bromide bound to DNA was recognized in the destructed and their neighboring wounded tissues under epifluorescent microscope. DNA from potato hybrid 96-56 (R1 gene) was treated with various restriction enzymes (Eco RI, Bam HI, Hha I and Hae III) and rubbed with a cotton ball on the potato leaves of cultivar Irish Cobbler (r gene) and zoospores of Phytophthora infestans were inoculated. Eco RI treated plot showed no difference with the control (without treating with enzymes), but Hae III and Hha I treated plots showed few flecks. From this result, fleck formation activity of exogenous DNA seemed to be almost completely destroyed by the Hae III and Hha I treatments. Fraction I protein (FIP) in potatoes with different susceptibility to P. infestans was investigated by isoelectrofocussing. Irish Cobbler (gene r) lacks 1 band in the small subunit of FIP as compared with other cultivars used. When the DNA from the hybrid 96-56 (gene R1) resistant to the race O of P. infestans was rubbed on leaves of Irish Cobbler, resistant flecks were recognized besides susceptible lesions, but electrofocussing pattern of the small subunit of FIP showed no band specific to the hybrid 96-56.
