Technical Abstract: Cottonseed, containing 22.5% protein, remains an under-utilized and under-valued resource due to the presence of toxic gossypol. RNAi-knockdown of Beta-cadinene synthase gene(s) was used to engineer plants that produced ultra-low gossypol cottonseeds (ULGCS). In the original study, we observed that cotton plants that were a month or older maintain normal complement of gossypol and related terpenoids in the roots, foliage, floral organs, and young bolls. However, the terpenoid profile of the RNAi lines during the early stages of germination, under normal conditions and in response to pathogen exposure, had not been examined. Results obtained in this study show that during the early stages of seed germination/seedling growth, in both non-transgenic and RNAi lines, the tissues derived directly from bulk of the seed kernel (cotyledon and hypocotyl) synthesize little, if any new terpenoids. However, the growing root tissue and the emerging true leaves of RNAi seedlings showed normal, wild-type terpenoid levels. Biochemical and molecular analyses showed that pathogen-challenged parts of RNAi seedlings are capable of launching a terpenoid-based defense response. Nine different RNAi lines were monitored for five generations. The results show that, unlike the unstable nature of antisense-mediated low seed-gossypol phenotype, the RNAi-mediated ULGCS trait exhibited multi-generational stability.