02169naa a2200169 a 450000100080000000500110000800800410001910000190006024501750007926000090025452015750026365000110183865300210184965300300187070000160190077300830191610159152015-08-21       2007    bl uuuu     u00u1 u    #d1 aSTADNIK, M. J.  aAssociation between lipoxygenase and peroxidase activity and systemic protection of cucumber plants against Podosphaera xanthii induced by Oudemansiella canarii extracts.  c2007  aThis study was done to determine the relationship between the changes in lipoxygenase (LOX) and peroxidase (POX) activity and the protection of cucumber ( Cucumis sativus ) against powdery mildew ( Podosphaera xanthii ) induced by hexane or ethyl acetate extracts of basidiocarps of Oudemansiella canarii . At the two-leaf stage, only the primary leaves of the greenhouse grown cucumber plants were sprayed with either extract. The secondary leaves were inoculated at 1, 4, 7 or 10 days after the spray and the number of powdery mildew colonies were counted after 6 days. The LOX and POX activity in secondary leaves was determined 24 h after inoculation.In vitroantimicrobial effect of the extracts was tested against Bacillus and Cladosporium . Maximum disease reduction (85%) occurred when plants were inoculated one day after applying hexane extract. The disease reduction then decreased abruptly to 30% on the 4day, but then increased again when plants were inoculated seven or ten days after treatment. LOX activity increased only by the hexane extract application, but not by the pathogen. POX activity was higher in inoculated plants previously treated with the hexane extract. On the other hand, ethyl acetate extract did not affect the enzyme activity and its protection efficacy decreased continuously with increasing time interval between treatment and inoculation. Although both extracts showed antimicrobial activityin vitro, the results suggest that apolar compound(s) from the basidiocarps of O. canarii also induce systemic resistance to powdery mildew.  aPepino  aExtrato fúngico  aIndução de resistência1 aBETTIOL, W.  tJournal of Plant Diseases and Protection, Stuttgartgv.114, n.1, p.9-13, 2007.