Abstract: 【Objective】 The narrow genetic basis and limited genetic diversity of germplasm resources were the main bottlenecks of genetic and breeding researches of cucumber (Cucumis sativus L.). This research aimed to create different euploidy and aneuploidy cucumber germplasm materials, and to establish a reliable method for identifying chromosomal constitution of the new materials, which would lay a foundation for the researches of screening chromosome lines, chromosome localization and genetic breeding. 【Method】 The germinating seeds of the North China ecotype inbred line ‘Changchunmici’ of C. sativus were treated with 0.4% colchicine solution to induce the chromosome doubling. Autotriploid was obtained through culturing the 35-45 d zygotic embryo from the cross of the induced autotetraploid and diploid. The chromosomal ploidy or number of the induced plants and hybrids were investigated using chromosome counting, combined with the morphology, leaf stomata under electron microscope scanning. Fluorescence in situ hybridization (FISH) was carried out to ascertain the chromosomal constitution of the induced plants based on the number, intensity and location of specific probe signals. 【Result】 According to the ploidy identification based on the mitotic metaphase chromosome number, eight autotetraploidy plants (2n=28) and three aneuploidy plants (2n=16, 19, or 27) were obtained in this study. Autotriploid plants (2n=21) were produced from the cross of autotetraploid and diploid. FISH signals of Type III (cucumber centromere probe) and 45S rDNA were multiple changes among diploid, triploid and tetraploid. The result further indicated the ploidy level. There were differences in morphologic characteristics among different ploidy plants of ‘Changchunmici’. Compared with diploid, tetraploid had significant differences in morphologic characteristics. The difference among triploid, aneuploidy and diploid were not significant, but the aneuploid grew weaker and with late flowering period and low fruit setting rate. Results from leaf stomata under electron microscope scanning showed that there were differences among different ploidy plants. With the increase of ploidy, the length and width of leaf stomata rose notably, but the stomatal density declined obviously, which could be used as an aid for identifying the ploidy of cucumber. The tandem repetitive sequence (45S rDNA and Type III) and chromosome-specific single copy gene Csa006700 were used as FISH probes to identify chromosomal constitution of the aneuploidy plant with the chromosome number of 16. FISH results from repetitive probes on the mitotic metaphase chromosomes showed that the extra two chromosomes were chromosomes 1 or 2. Further, the chromosome 2 specific gene probe-Csa006700 showed the signals on one pair of chromosomes. These results confirmed that this aneuploidy plant was assigned as tetrasome polyploidy with two extra chromosome 1 of cucumber (2n=14+2). These results confirmed that colchicine could directly not only induce autopolyploid, but also induce a variety of aneuploid. 【Conclusion】 It is a rapid method to create cucumber different euploidy and aneuploidy germplasm materials using colchicine, and the chromosomal constitution could be identified by FISH analysis based on the chromosome specific probes.

Key words: cucumber , colchicine , euploid , aneuploid , fluorescence in situ hybridization (FISH)