Abstract: The expression of disease resistance related genes in cucumber（Cucumis Sativus L.）seedlings inoculated by Cladosporium cucumernium strain with weak virulence was analyzed among 72 hours by cDNA-AFLP method in this study. The results showed that the difference of gene expression began at 3 hours after inoculation, and the number of differential expression fragments reached the maximum at 6 hours after inoculation. The number of induced gene fragments was more than that of inhibited gene fragments at 8 time points after inoculation, but the results was not the same at 12 hours after inoculation. Through recovery，cloning，sequencing and homology analysis，5 obtained fragments share high homology with salicylic acid lucosyltransferase，Pyrus communis phosphatidyl glycerol specific phospholipase C-like mRNA，etc. respectively. We concluded that disease resistance of cucumber induced by inoculation of Cladosporium cucumernium strain with weak virulence might depend on signal transduction pathway mediated by salicylic acid，further induce system acquired resistance（SAR）. Phospholipase C，as one of the key enzyme of signa transduction in stress tolerance，could be involved in the process described above. Northern blot results further proved the differential fragments was induced by the inoculation of Cladosporium cucumernium.

Key words: cucumber, cDNA-AFLP, Cladosporium cucumernium, induced resistance to diseases, differential expression