01782naa a2200217 a 450000100080000000500110000800800410001902200140006010000130007424501310008726000090021852011720022765000260139965000120142565000110143765000260144865000110147465300130148570000190149877300470151716328521993-11-08       1993    bl uuuu     u00u1 u    #d  a0031-949X1 aAFEK, U.  aTemperature and gamma irradiation effect on scoparone, a citrus phytoalexim confering resistance to Phytophthora citrophthora.  c1993  aThe effect of gamma irradiation and temperature of incubation on accumulation of the phytoalexin scoparone were irrigated in citrus inoculated with the fungus Phytophthora. In all the tested citrus species, scoparone concentration in the branches was higher and lesion lenght was shorter when the incubation temperature after inoculation with P. citrophthora was 28 rather than 20 C. The temperature effect was pronounced, especially in inoculated branches of rough lemon, which after 4 days at 28 C had a scoparone concentration of 290 ug/g fresh weight, compared with 42 ug/g fresh weight at 20 C. The comparable lesion lenght in this species was 5.2 mm at 28 C compared with 11.0 mm at 20 C. Gamma irradiation affected citrus resistance only at 300-400 Krad. Maximumscoparone concentration in inoculated branches accumulated after irradiation with 400 Krad and reached 970 and 530 ug/g fresh weight in macrophylla and sour orange, respectively, and 100 and 82 ug/g fresh weight in rough lemon and shamouti, respectively. In the fruit, a maximum scoparone concentration of 94.7 ug/g fresh weight accumulated in inoculated grapefruit after irradiation with 200 Krad.  aGuignardia citricarpa  aLaranja  aLimão  aPenicillium Digitatum  aRizoma  aControle1 aSZTEJNBERG, A.  tPhytopathologygv.83, n.7, p.753-758, 1993