Genetically modified potato (Solanum tuberosum L.)
resistant to potato tuber moth (Phthorimaea
M.A. Ibrahim* , E.A. Metry*, Y.A. Osman**, T.M. Nasr El-Din*, and M.A. Madkour*
Agricultural Genetic Engineering Research Institute (AGERI), ARC, Giza. Egypt.
Department of Botany, Faculty of Science, Mansoura University, Mansoura, Egypt.
Potato tuber moth (PTM), Phthorimaea operculella, causes tremendous
economic losses to potato production in Egypt. An Egyptian isolate of the
entomopathogenic bacteria Bacillus thuringiensis (Bt), isolate C12, produces a potent
Cry1Aa7 toxin that kills the larval stages of PTM, more efficiently than other
standard Bt toxins. The cry1Aa7 gene cloned in the binary vector pBI-121 and pBI-
cry7 construct was transformed to Agrobacterium tumefaciens strain LBA4404 via
triparental mating. Transformed LBA4404 strains harboring pBI-cry7 were used to
mobilize the cry1Aa7 cassette into the potato cultivar Desiree. Out of 91
transformants, five individual lines (D8, D9, D13, D26 and D37) were shown to be
transgenic for cry1Aa7. The integrated toxin gene as well as the expressed Cry1Aa7
was confirmed using polymerase chain reaction (PCR) and enzyme-linked
immunosorbant assay (ELISA), respectively. The expression of cry1Aa7 gene was
only detected in the leaves of three lines. Lines D13, D26 and D37 produced 0.3, 0.79
and 3.3 µg toxin per gram tissue, respectively; whereas Cry1Aa7 was not detected in
lines D8 and D9. The transformed tubers were challenged by releasing PTM larvae
(1st instar) and emerged adults were scored. Our results revealed that the transformed
tubers sustained insect attack 30-40% better than their non-transformed counterparts.
Key words: Potato, genetically modified, tuber moth.