A Functional Genomics Approach for the Identification of Genes Involved in the Biosynthesis of the Allelochemical Sorgoleone

摘要

Several Sorghum species are allelopathic, producing phytotoxins such as sorgoleone and its analogues. Sorgoleone accounts for much of this phytotoxicity, representing up to 90% (w/w) of the content of Sorghum bicolor root exudates. Previous and ongoing studies suggest that the biosynthetic pathway for this compound involves a polyketide synthase activity utilizing atypical long chain fatty acyl-CoA starter units, resulting in the addition of a quinone head via iterative extender unit condensations. An expressed sequence tag (EST) study was performed using random sequences from a Sorghum bicolor root hair-specific cD"NA library, and highly expressed candidate sequences representing all of the putative enzyme classes required for the sorgoleone biosynthetic pathway were identified.