Insecticide-Resistant Maize Plants Regenerated in Vitro

Abstract

Susceptibility to damage by insecticides is generally not a problem for agronomic crops due to early screening during the variety development phase. However, maize carrying the Texas male sterile cytoplasm (cms-T), but not other cytoplasms, is selectively damaged by the insecticide carbamate methomyl (active ingredient of Lannate). The cytoplasm-specific susceptibility is similar, and possibly identical, to susceptibility to the T toxin from the fungus Bipolaris maydis race T, the agent responsible for southern corn leaf blight in cms-T maize (Humaydan and Scott 1977; Koeppe et al. 1978). The similar selectivity of these compounds may be due to the cms-T-specific gene product of T-utf 13, a mito-chondrial membrane protein designated URF13, that interacts with both methomyl and T toxin (Wise et al. 1987a; Dewey et al. 1988, Huang et al. 1990). The binding of methomyl or toxin presumably opens membrane channels, leading to massive ion leakage, loss of membrane potential, and thus arrest of oxidative phosphorylation (Braun et al. 1989, 1990; Levings 1990).