Present address: Sabarinath Sundaram, Department of Biology, Texas A&M University, College Station, TX, 77843, USA.
Ultra-low gossypol cottonseed: generational stability of the seed-specific, RNAi-mediated phenotype and resumption of terpenoid profile following seed germination
Article first published online: 8 SEP 2011
© 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd
Plant Biotechnology Journal
Volume 10, Issue 2, pages 174–183, February 2012
How to Cite
Rathore, K. S., Sundaram, S., Sunilkumar, G., Campbell, L. M., Puckhaber, L., Marcel, S., Palle, S. R., Stipanovic, R. D. and Wedegaertner, T. C. (2012), Ultra-low gossypol cottonseed: generational stability of the seed-specific, RNAi-mediated phenotype and resumption of terpenoid profile following seed germination. Plant Biotechnology Journal, 10: 174–183. doi: 10.1111/j.1467-7652.2011.00652.x
- Issue published online: 2 JAN 2012
- Article first published online: 8 SEP 2011
- Received 20 April 2011; revised 7 July 2011; accepted 11 July 2011.
- gene silencing;
- seed-specific promoter;
Cottonseed, containing 22.5% protein, remains an under-utilized and under-valued resource because of the presence of toxic gossypol. RNAi-knockdown of δ-cadinene synthase gene(s) was used to engineer plants that produced ultra-low gossypol cottonseed (ULGCS). In the original study, we observed that RNAi plants, a month or older, maintain normal complement of gossypol and related terpenoids in the roots, foliage, floral organs, and young bolls. However, the terpenoid levels and 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 defence 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.