Effect of potato seed tuber glycoalkaloid content on subsequent infection byRhizoctonia solani

Since glycoalkaloids have been shown to have fungitoxic properties, it is important to know what impact this might have on potato plant breeding programs which select for low levels of total glycoalkaloids (TGA) in the tuber. Potato clones with TGA levels ranging between 1.6 and 32.8 mg/100 g fresh tissue were planted in two trials to evaluate the relationship between seed tuber TGA and incidence ofRhizoctonia solani infection in the developing plant. An inoculation procedure was followed in the greenhouse and field to establish uniform infection of potato seedlings. Plants were examined for lesion development on stems and stolons and assigned disease ratings. In the field, yield of malformed tubers was recorded and included in the overall disease ratings. The results reported herein indicate that TGA levels in the seed tuber are unrelated to the severity ofR. solani infection in the seedling.