Abstract: A set of reciprocal crosses with different chromosome level made between Cucumis sativus and C.hystrix as the experiment system was used to investigate the difference of morphology , fertility and DNA. The
diameter of stem , the length of petiole , the shape and size of leaves were intermediated when compared to parents. The branching number and the appearance of first female flower showed paternal transmission while the length of inter-node of main stem showed maternal transmission in all of hybrids. The RAPD results indicated fifteen arbitrary primer band patterns were different among the four types of hybrids , and only six were the same. Some fragments obviously showed the paternal expression in the reciprocal cross. The fertility of reciprocal plants were great different . When C. hystrix used as female , the tetraploid (2n = 38) / diploid (2n = 19) plants had the higher fruit sets , and even the amphidiploidy plants could produce viable seeds. However , when the cucumber used as female , both tetraploid/ diploid plants were highly sterile and had very low fruit sets.

Key words: Cucumis, Interspecific hybridization, Reciprocal differences, RAPD