Submitted to: Royal Society of Chemistry Meetings
Publication Type: Abstract Only
Publication Acceptance Date: July 12, 2010
Publication Date: July 12, 2010
Citation: Stipanovic, R.D., Puckhaber, L.S., Wheeler, M.H., Liu, J., Bell, A.A. 2010. Establishing the biosynthesis of the plant toxin fusaric acid using non-radio labeled precursors [abstract]. Proceedings of Royal Society of Chemistry Meetings, July 6-9, 2010, San Francisco, California. 2010 CDROM. Technical Abstract: Fusarium oxysporum f. sp. vasinfectum (F.o.v.) race 1 is a widespread plant pathogen that attacks cotton, alfalfa and okra in the U.S. The recent discovery of races 3 and 4 not previously found in the U.S. is of particular concern to the cotton industry. In addition, a similar but more virulent biotype was recently inadvertently introduced into the U.S. on cottonseed imported into California from Australia. The Australian F.o.v. biotype and races 3 and 4 cause significant plant root degradation and are virulent in heavy soil in the absence of nematodes. This root rotting and climatic adaptation differentiates these biotypes from previously identified less virulent U.S. F.o.v. races 1 and 2. In addition, the Australian F.o.v. biotype and races 3 and 4 produce prodigious quantities of the phytotoxin fusaric acid. To combat the threat of these new races/biotype to U.S. cotton production, we have begun a systematic investigation of fusaric acid to unequivocally determine its biosynthesis and use gene knockout to demonstrate the role of fusaric acid production in the pathogenicity of these new virulent isolates. To this end, we have conducted a series of 13C-labeled feeding studies that show fusaric acid is biosynthesized via a mixed polyketide synthase and a nonribosomal peptide synthase. Knockout of the polyketide synthase gene significantly reduces pathogenicity in the Australian F.o.v. biotype.