Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/27/2012
Publication Date: 2/27/2012
Citation: Wagner, T.A., Liu, J., Stipanovic, R.D., Puckhaber, L.S., Bell, A.A. 2012. Hemigossypol, a constituent in developing glanded cottonseed (Gossypium hirsutum). Journal of Agricultural and Food Chemistry. 60:2594-2598. Interpretive Summary: Cotton contains a unique group of terpenoids that are part of the cotton’s defense system against pathogenic fungi and insects. The foliage terpenoids include desoxyhemigossypol, hemigossypol, gossypol, hemigossypolone, and the heliocides. In the seed and roots gossypol is the predominant terpenoid. Gossypol is the primary limiting factor for using cottonseed in feeds and food. Though hemigossypol has been assumed the precursor of gossypol from its first discovery, it has never been isolated from healthy cottonseed. Our manuscript describes the first identification of hemigossypol from developing cottonseed and provides evidence that hemigossypol is indeed the biosynthetic precursor of gossypol. This information is important for planning molecular approaches to block or alter gossypol synthesis in cottonseed.
Technical Abstract: Gossypol is a dimeric sesquiterpenoid first identified in cottonseed, but found in various tissues in the cotton plant including the seed. From its first discovery, it was assumed that hemigossypol was the biosynthetic precursor of gossypol. Previous studies established that peroxidase (either from horseradish or from cottonseed) converts hemigossypol to gossypol. However, hemigossypol has never been identified in healthy cottonseed. In a temporal study using HPLC and LCMS, hemigossypol was identified in the developing cotton embryo and was shown to concomitantly accumulate with gossypol and with transcripts of delta-cadinene synthase and 8-hydroxy-delta-cadinene synthase, genes involved in the biosynthesis of hemigossypol and gossypol until 40 days-post-anthesis (dpa). Thereafter, hemigossypol and its biosynthetic gene transcript levels declined, while gossypol level remained almost unchanged until the bolls were open. Taken together with previous experiments, this establishes hemigossypol as the biosynthetic precursor of gossypol.