Abstract: In order to demonstrate that the synthetic allotetrop loid species (Cucum is hytivus Chen and Kirkbride. , 2n = 38) was the hybrids progeny originated from crossing between the wild Cucumis species (C.hystrix Chakr. , 2n = 24) and the cultivated cucumber‘Beijing J ietou’(C. sa tivus L. , 2n = 14) in molecular level, primers were designed according to the 6-phosphogluconate dehydrogenase ( 6PGDH) gene cDNA sequence of cucumber (GenBank accession number: EU815934). The 6PGDH gene fragmentswere amplified
from allotetroploid, the wild Cucumis and cultivated cucumber‘Beijing Jietou’, respectively. Sequence analysis showed that the 6PGDH fragments in three species were highly homologous, having 1 098 bp length each.It encompassed of 936 bp long open reading frame (ORF) encoding 311 amino acids and had 162 bp non-translation 3′- terminal end region (3′UTR) , no intron existed in 6PGDH fragment.The sequences were analyzed by software program DNAMAN, detected three variable amino acid locips and twenty-two bases locips.The inheritance of variable locips were congruence with theMendelps genetics law of inheritance, therefore, it is proven atmolecular level that this synthetic allotetraploid species was the hybrid originated from C. hystrix and C. sativus‘Beijing J ietou’crossing.

Key words: cucumber, allotetrop loid, 6PGDH, hybrid, clone