Abstract: Proteomic app roaches using two-dimensional gel electrohoresis (2-DE) were adop ted to identify proteins from cucumber leaves differentially exp ressed in F₂ generation of cucumber. Nearly 500 proteins were reproducibly detected, including 39 specific p roteins exp ressed in F2 sensitive pool samp les and 2-specific p roteins exp ressed in resistance pool samp les, 35 proteinswere two-fold upper limit and 46 proteins were two-fold lower limit. Analysiswith MALDI-TOF-MASS showed that nine important proteins associated with de2
fensive reaction were identified in F₂ cucumber, a protein of disease resistance gene ( SSP3110) , 14-3-3 brain protein homolog ( SSP1411) , cop roporphyrinogen Ⅲ oxidase ( SSP5513) , carbonic anhydrase ( SSP5412) ,
alpha2galactosid2ase2like p rotein ( SSP5710) , putative p rotein ( SSP6002) , 1718 kDa class small heat shock protein ( SSP0710) , hypothetical p rotein ( SSP3111) , ( S) -2-hydroxy-acid oxidase ( EC1.1.3.15) -cucur-bit ( SSP4610). All of those proteinswere probably parts of network of resistance or development-related proteins. This study gives new insights into cucumber powderymildew resistant response in cucumber leaves and demonstrates the power of the proteomic app roach in plant biology studies.

Key words: Cucumber, Powdery mildew, Protein, Two-dimensional gel electrophoresis, Mass spectrometry