ARS | Publication request: BIOSYNTHESIS OF O-HIBISCANONE, A PHYTOALEXIN FROM KENAF (HIBISCUS CANNABINUS)

Submitted to: International Congress of Pesticide Chemistry Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: December 12, 1997
Publication Date: N/A

Technical Abstract: The fungal wilt pathogen Verticillium dahliae causes serious disease losses of vegetables, berries, trees, ornamentals and field crops. Idessis showed that kenaf (Hibiscus cannabinus), which is a member of the Malvaceae family, is highly resistant to this pathogen. We have identified the potent phytoalexin o-hibiscanone (o-HBQ) from inoculated kenaf stems. Cotton, which is also in the Malvaceae family, produces a number of phytoalexins among which desoxyhemigossypol (dHG) is the most effective. dHG, however, is only about 1/3 as potent as o-HBQ. dHG is derived from nerolidyl diphosphate via delta-cadinene. If o-HBQ is derived from the same precursor as dHG, then introduction of only a few genes from kenaf could allow o-HBQ production in cotton and, consequently, increase resistance to Verticillium wilt. Several cadinene type sesquiterpenoids have been isolated from both kenaf and cotton which suggests they may share a common biosynthetic origin. The structure of these putative intermediates and the results of 13C-labeling experiments will be presented.