In preparation for field testing transgenic plants, regenerated plants and their progeny were screened for a T-DNA insertion which carried the neomycin phosphotransferase II (nptII) gene and a modified gene from Bacillus thuringiensis kurstaki strain HD-1 (B.t.). Whole plant measurements and segregation data were collected in order to identify the best plants for generation advancement. An ordinal selection index was established to discriminate between segregating individuals which displayed superior agronomic properties. Deoxyribonucleic acid amplification by PCR analysis and nptll protein analysis were used to follow the foreign genes into subsequent generations. Seeds from the best plants were bulked into four populations which were sent to Mississippi for further laboratory and field testing.

As part of our continuing efforts to improve insecticidal proteins, refinements in B.t. expression have been made through modifications to the promoter region, signal peptides and to the B.t. coding sequence. These chances have led to a 1000 fold increase in the levels of expression of B.t. protein in plants. Beyond the use of B.t. insecticidal proteins, we have been investigating other types of toxins. Insecticidal proteins based on venom toxins derived from arthropods are being evaluated for activity against various cotton insect pests.