(-DELTA-CADINENE IS A PRODUCT OF SESQUITERPENE CYCLASE ACTIVITY IN COTTON())

Glandless cotton cotyledons stimulated to produce sesquiterpenoid phyt oalexins by inoculation with Xanthomonas campestris pv. malvacearum, o r by injection of oligogalacturonide elicitors, generated a hydrocarbo n that was absent in mock-inoculated or non-inoculated cotyledons. Enz yme preparations from the same cotton cotyledons catalysed cell-free r eactions which converted (E,E)-[1-H-3]farnesyl pyrophosphate into a pr edominant tritium-labelled hydrocarbon product. Large-scale cell-free reactions catalysed by enzyme preparations from cotton cotyledons prev iously inoculated with Xanthomonas campestris pv. maluacearum converte d nonradioactive (E,E)-farnesyl pyrophosphate into the hydrocarbon pro duct, which was identified as (+)-delta-cadinene by chiral GC-mass spe ctrometry. In planta incorporation of tritium into the sesquiterpenoid phytoalexins 2,7-dihydroxycadalene, lacinilene C, lacinilene C7-methy l ether and structurally related terpenoids occurred following injecti on of [H-3](+)-delta-cadinene into previously inoculated glandless cot ton cotyledons. The accumulation of (+)-delta-cadinene in bacteria-ino culated or elicitor-treated cotton cotyledons and the results of the i ncorporation experiment suggest that (+)-delta-cadinene is an early en zymatic intermediate in the biosynthesis of the sesquiterpenoid phytoa lexins by upland cotton.