1National Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology, SIBS; 2Shanghai Research Center of Life Sciences, The Chinese Academy of Sciences, Shanghai 200032, China; 3Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, U.S.A.
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Accepted 3 September 1999.
Cotton plants accumulate sesquiterpene aldehydes in pigment glands. The two enzymes farnesyl diphosphate synthase (FPS) and (+)-δ-cadinene synthase (CAD), a sesquiterpene cyclase, are involved in the biosynthesis of these secondary metabolites. A full-length cDNA (garfps) encoding FPS was isolated from Gossypium arboreum and identified by in vitro enzymatic assay of the garfps protein heterologously expressed in Escherichia coli. Treatment of G. arboreum suspension-cultured cells with an elicitor preparation obtained from the phytopathogenic fungus Verticillium dahliae dramatically induced transcription of both FPS and CAD, paralleling the accumulation of the sesquiterpene aldehydes in these cells. For G. australe, a wild species from Australia, the V. dahliae elicitor preparation also caused an induction of FPS but only a low rate of induction of CAD, apparently because of a constitutive expression of the sesquiterpene cyclase gene in suspension-cultured cells. Two transcripts and proteins of FPS were detected in the elicited G. australe cells; the smaller FPS seemed to be de novo synthesized after elicitation. Furthermore, G. australe-cultured cells accumulated the cadinene, instead of sesquiterpene aldehydes, indicating that the biosynthetic pathway leading to sesquiterpene aldehydes was absent or blocked after FPP cyclization.
© 1999 The American Phytopathological Society