Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/20/2003
Publication Date: 2/21/2004
Citation: Stipanovic, R.D., Puckhaber, L.S. 2004. Identification of (+)-3-hydroxy-alpha-calacorene in cotton and kenaf. Proceedings of Beltwide Cotton Conferences. p. 2176-2180. Interpretive Summary: Wilt pathogens significantly reduce cotton yields in the U.S. When cotton is attacked by these pathogens, the plant produces chemicals that will kill the pathogen. Kenaf is a plant that is related to cotton, but it is much more resistant to wilt pathogens than cotton. It also produces a chemical that is more toxic to the pathogens than any chemical produced by cotton. We have discovered several chemicals that occur in both cotton and kenaf. We have reason to believe that one of these (3-hydroxy-alpha-calacorene) is changed into the potent chemical produced in kenaf. However, this chemical can exist in two different forms that differ from each other just as right and left hands of a person differ from each other. We were able to show that these two plants produce exactly the same forms of the chemical. This means that it will be much easier to introduce this characteristic into cotton from kenaf using gene modifications.
Technical Abstract: When attacked by pathogens, cotton responds by synthesizing antimicrobial compounds called phytoalexins. As a means to increasing the resistance of cotton to wilt pathogens, we are investigating biosynthetic pathways that could be utilized to introduce more potent phytoalexins. A phytoalexin produced by kenaf, Hibiscus cannabinus, is significantly more potent toward wilt pathogens than is any phytoalexin produced by cotton. We have established that a purported common intermediate in the biosynthetic pathway of phytoalexins in cotton and kenaf, 3-hydroxy-alpha-calacorene, is the (+)-enantiomer in both plants.