Title: Ultra-low Gossypol cottonseed: Stability and specificity of the RNAi-mediated trait and performance of transgenic lines under field conditions Authors
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: December 13, 2012
Publication Date: N/A
Technical Abstract: Cottonseed, containing 22.5% protein, remains a low-value byproduct of lint production mainly due to the presence of toxic gossypol that makes it unfit for monogastrics. RNAi-knockdown of d-cadinene synthase gene(s) was used to engineer plants that produced ultra-low gossypol cottonseed (ULGCS). The RNAi plants maintain normal complement of gossypol and related terpenoids in the roots, foliage, floral organs, and young bolls. Upon germination, the growing root tissue and the emerging true leaves of the young RNAi seedlings showed normal, wild-type terpenoid levels. Importantly, biochemical and molecular analyses showed that pathogen-challenged parts of the young RNAi seedlings are capable of launching a terpenoid-based defense response. Nine different RNAi lines were monitored for five generations under greenhouse conditions and the ULGCS trait was found to exhibit generational stability. In addition, field trials conducted over a period of three years showed that the ULGCS trait was stable in the field and the foliage/floral organs of transgenic lines contained wild-type levels of gossypol and related terpenoids. Visual monitoring of the plants throughout the growing seasons did not reveal any differences between the ULGCS lines and their non-transgenic counterparts in terms of the susceptibility to pests or pathogens. Importantly, we did not observe any negative effects on either the yield or quality of the fiber and seed in the transgenic lines compared to the non-transgenic parental plants. Interestingly, the ULGCS had significantly higher (4-8%) oil content compared to the seeds from the non-transgenic parent. Field trial results confirmed the stability and specificity of the ULGCS trait suggesting that this, RNAi-based product has the potential to be commercially viable. Thus, it may be possible to enhance and expand the nutritional utility of the annual cottonseed output to fulfill the ever-increasing needs of humanity.