Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/4/1997
Publication Date: N/A
Interpretive Summary: Tobacco budworm and bollworm are pests of major importance in cotton production. Transgenic cotton plants, recently developed, confer resistance to these two pests via the toxic protein produced by a gene originally found in a common soil bacteria, Bacillus thuringiensis var kurkstaki. Several transformation events from Monsanto with either the cryIA(c) or cryIIA gene and several from Calgene, Inc., with the cryIA(c) gene, were evaluated to select events to use as parents in breeing programs. Backcrossed derived lines from Delta and Pine Land Seed Company and from Jacob Hartz (now Paymaster Technologies), containing the gene cryIA(c) were evaluated for resistance to tobacco budworm in the field and for agronomic performance. Artificial infestation with neonate tobacco budworm or bollworm were used to evaluate the lines and transformation events. No insecticide for caterpillars was applied to the plots infested with larvae. Plots were also grown without infestation and with full season insect control. Two Monsanto transformation events with the cryIIA gene were as effective as their events with the cryIA(c) gene. These provide a second gene to use with the cryIA(c) gene in resistance management. Several transformation events from Calgene with cryIA(c) genes were resistant and three combined this with yield of parents. Two Delta and Pine Land Seed Company lines with the cryIA(c) gene were resistant to tobacco budworm and produced yields equal to or greater than the recurrent cultivar parent. Six lines from Hartz Seed Company carried the cryIA(c) gene and were resistant to tobacco budworm. Two Hartz resistant lines equaled Hartz 1244 in yield.
Technical Abstract: In Gossypium hirsutum L., upland cotton, regeneration is more successful in Coker cultivars. Transformed plants with the cryIA(c) or cryIIA gene from Bacillus thuringiensis Kurstaki which code for cryIA(c) or cryIIA delta endotoxins, respectively, have been developed and are toxic to certain pests of cotton. Each transformation event should be evaluated so the best parental lines can be chosen for breeding. We grew field plots of several transformation events in Coker 312 from Monsanto Co. and in Coker 130 from Calgene, plus lines derived via backcrossing the cryIA(c) gene into cultivars by Delta & Pine Land Seed Co. and Jacob Hartz Seed Co. were grown with (w/larvae) and without (w/o larvae). Plants in the w/larvae plots were artificially inoculated with either Heliothis virescens (F.), tobacco budworm, or Helicoverpa zea Boddie, bollworm. Two Monsanto events with the cryIIA gene were as effective as lines with the cryIA(c) gene. These events provide a second gene for use along with the cryIA(c) gene to aid in resistance management. Several events with the cryIA(c) genes from Calgene were resistant to tobacco budworm. Three events, ST 317BT, ST 807BT, and ST 808BT combined resistance with yields equal to Coker 130 in the 1995 tests. Two backcross lines from Delta & Pin Seed Co. with the cryIA(c) gene (Bollgard TM), NuCOTN 33 B and NuCOTN 35 B were resistant to tobacco budworm and produced yields greater than or equal to the recurrent cultivar. These were available to growers in 1996. Seed lots of backcross lines from Hartz contained a small percentage of seed without the cryIA(c) gene; however, each exhibited acceptable resistance to tobacco budworm. Only HX2 BG and HX3 BG combined resistance with yields equal to H1244.