Tissue-Specific and Developmental Analysis of Gossypol and Related Terpenoids in Cotton Plants Engineered to Knock-Down d-Cadinene Synthase Activity in a Seed-Specific Manner

We utilized RNA interference (RNAi) to disrupt a key step in the biosynthesis of gossypol in a seed-specific manner in cotton (Gossypium hirsutum L.; Sunilkumar et al. 2006, PNAS 103: 18054-18059).  Targeted engineering of the gossypol biosynthetic pathway by interfering with the expression of the δ-cadinene synthase gene during seed development resulted in a significant reduction in cottonseed-gossypol levels.  This trait, based on RNAi-mediated silencing, is heritable and was found to be stable over many generations in several lines.  We have begun a systematic study of gossypol and related terpenoids in relation to tissue-specificity and plant development.  In addition, these plants are being examined for their response to various pathogens.  We are also comparing the low seed-gossypol, RNAi lines with antisense lines as well as with a traditionally bred, Acala-type glandless variety.   Results from these analyses and their significance will be presented.