Evaluation of natural and engineered resistance mechanisms in Solanum tuberosum for resistance to Phthorimaea operculella (Lepidoptera: Gelechiidae).
Potato tuber moth (Phthorimaea operculella) is a highly destructive pest of cultivated potato and is responsible for damage to both leaf and tuber tissues. Host plant resistance is a central component to developing an integrated pest management program to control P. operculella. Studies were conducted to test the efficacy of a codon-modified CryV-Bacillus thuringiensis (CryV-Bt) gene constitutively expressed in potato and the combined effect of CryV-Bt expression with natural host plant resistance mechanisms in potato. Lemhi Russet and 2 lines with host plant resistance mechanisms, USDA8380-1 (leaf leptines) and L235-4 (glandular trichomes), along with the CryV-Bt-transgenic lines of each of these 3 genotypes were examined. Detached leaf bioassays were conducted to examine control of P. operculella. Nontransformed Lemhi Russet and L235-4 were susceptible to P. operculella while 54% mortality was observed when first-instar larvae were fed on USDA8380-1 leaves. High levels of expression occurred in the CryV-Bt transgenic lines, with up to 96% P. operculella mortality. These transgenic lines provide a germplasm base to examine combined insect resistance mechanisms as a means to achieve durable host plant resistance.