1a.Objectives (from AD-416)
1) Identify molecular markers associated with resistance to Cry3Bb1 Bt corn in replicated colonies of WCR populations that are reared on isoline or Bt corn.
2) Test the dominance of resistance and fitness costs to Bt corn.
3) Develop colonies with resistance to Cry34Ab1 + Cry35Ab1.
4) Evaluate the potential for cross resistance between current Bt products and stacked events.
1b.Approach (from AD-416)
A genome scan using a large number of SNP markers will be used to identify markers associated with the resistant phenotype. Crosses of resistant and susceptible lines will be developed and evaluated. We will use techniqes of Meils et al. (2008) and Lefko et al. (2008) to develop a set of resistant colonies in both Ames and Columbia. We hope to be able to evaluate for cross resistance between Cry3Bb1 resitance and Cry34Ab1 + Cry35Ab1 resistance. This will depend on successful MTAs, but Syngenta has already agreed that we can evaluate for cross resistance between MIR 604 resistance and resistance to Event 5307.
Work has begun on all phases of this project. Approximately 1000 individuals from the replicated colonies with resistance to Cry3Bb1 and their respective control colonies have been extracted for DNA and genotyped with 900 with microsatellite markers. A colonies selected for resistance to Cry34/35Ab1 is under development along with a seed mix colony, a block refuge colony, and a susceptible control colony from the same original population.
Monitoring activities included email exchange of information and results, telephone conference calls, and personal meetings at the Annual meeting of the Entomological Society of America.