2006 Annual Report 4d.Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the University of Nebraska - Lincoln. Additional details of research can be found in the report for the inhouse project 6408-21410-006-00D, Discovery and Development of Natural Product-Based Weed Management Methods. Preparation of RNA interference and overexpression vectors for manipulation of sorghum polyketide synthases involved in sorgoleone biosynthesis was completed. Isolation of promoter (5’ flanking region) sequences for both sorghum PKS genes was also accomplished. The overexpression and RNAi vectors were used to transform S. bicolor cultivar Tx430 via Agrobacterium at the University of Nebraska. Several RNAi and overexpression lines have been generated to date, and R1seed has been collected from these for analysis. A total of 10 transformant lines will be generated for each vector.