PEROXIDASE ISOZYME POLYMORPHISM AS A POTENTIAL MARKER FOR DETECTION OF FIELD-RESISTANCE IN CUCUMIS-SATIVUS TO CUCUMBER DOWNY MILDEW (PSEUDOPERONOSPORA-CUBENSIS (BERK ET CURT) ROSTOV)

Eleven cultivars and accessions of Cucumis sativus L. with various lev el of field resistance to cucumber downy mildew (Pseudoperonospora cub ensis (Berk. et Curt.) Rostov.) were screened for peroxidase isozyme p olymorphisms. There are no available general markers for the detection of field resistance. Considerable variation, characterized by occurre nce of seven different zymograms was detected in the studied set. Thes e zymograms should offer a quick and reliable method for the discrimin ation of specific cucumber (C. sativus) genotypes with high levels of field resistance against cucumber downy mildew (Pseudoperonospora cube nsis). These results could be applied to genetic studies and selection work focusing on the improvement of field resistance of cucumbers to P. cubensis.