01837naa a2200181 a 450000100080000000500110000800800410001902200140006010000200007424500850009426000090017952013460018865000110153465300260154565300140157170000150158577300550160016329971994-03-16       1993    bl uuuu     u00u1 u    #d  a0031-949X1 aBROWN, G. ELDON  aInteractions of ethylene with citrus stem-end rot caused by Diplodia natalensis.  c1993  aEthylene treatment of citrus fruit to improve rind color (degreening)significantly enhances the incidence of stem-end rot caused by Diplodianatalensis and stimulates disease development. In an effort. In an effort to identify the role of execessive exogenous ethylene in pathogenesis, tissue exposed to different ethylene and air atmospheres was taken from the base of contrus fruit adjacent to the abscission area at the point of fungal ingress and examined for the presence of fungal inhibitors and lignin. The major inhibitor, identified as scoparone (6,7-dimethoxycoumarin), accumulated most extensively in tissue taken from asymptomatic fruit receiving either high ethylene treatments (55 u1 L-1) followed by low inculum levels, or low ethylene treatments (2 u1 L- 1) followed by high inoculum levels.Accumulation of lignin, extracted from the same tissue and measured as lignothiogucolic acid, followed areponse  pattern similar to that observed for scoparone. Evidence for some role of scoparone and lignin in fruit resistance was indicated by the correlation between enhanced accumulation of these inhibitors and the lack of decay. However, other factors affected by high ethylene play a role in disease development since levels of inoculum that induced little disease at low ethylene were capalble of causing decay at high ethylene.  alignin  aPostharvest pathology  aScoparone1 aLEE, H. S.  tPhytopathologygv.83, n.11, p.1204-1208, nov.,1993