| A series of studies focusing on interspecific hybrid-Cucumis × hytivus Chen & Kirkbride were performed on the genetic character, isozyme markers and taxonomic position among Cucumis by employing isozyme electrophoresis techniques in addition to cytogenetic and molecular method. C. hytivus, C. hystrix, various of genotypic cucumber and melon were analysised in these studies to carry through above program. The results went as followed:The morphological traits except for internode length and No. of lateral branches are basically invariant between the five individuals of the first selfed progenies of C. hytivus. Although chromosome number of all materials studied was counted to be 2n = 38, the difference in meiotic behaviors between individuals of first selfed progenies were observed, which indicated the difference in the degree of diploidization. The isozyme analysis showed that the differences of bands pattern among first selfed progenies of new species and regenerated plant were very small in 4 isozyme sysytem (AAT, GDH, POD and ME). The difference in genetics reflected by the above three angle between selfed progenies and original amphidiploid was very small. These results indicated, as a new species C. hytivus has basically possessed genetic stability.The specific zymograms of C. hytivus in two enzyme systems, AAT and POD, were observed in different tissue at different stages. When compared with C. sativus, C. hytivus showed two additional bands (Rf = 0.26, Rf = 0.43) in AAT zymogram. C. hytivus, however, lost two bands (Rf = 0.50, Rf = 0.55) in POD zymogram and added an additional band (Rf = 0.67) when compared with C. sativus. Meanwhile, POD isozyme of C. hytivus showed tissue-specific expression and development-specific expression, while AAT isozyme only showed development-specific expression. And still the specially addition bands (two for AAT and one for POD) and specially lost bands (two for POD) was genetic stability in various tissue and developmental stages.Two polymorphic loci, Aat-1 and Aat-2, and one monomorphic locus, Aat-3, were observed in C. hytivus'parents and their progenies (BCFi). At Aat-1, in C. sativus fast-migrating anodic band coded for Aat-1 (2), however, in C. hystrix a slow-migrating cathodic band coded for Aat-1 (1). In contrast, in C. sativus at Aat-2 a slow-migrating cathodic band coded for Aat-2 (1), while in C. hystrix a fast-migrating anodic band coded for Aat-2 (2). C. hytivus exhibited the typical hybrid dimeric banding pattern. The difference in band intensity between C. hytivus and its backcross progenies (BCFi; C. sativus recurrent) were due to the dosage effects of alleles at Aat-1 and Aat-2. Aat-3 was monomorphic in this mating, encoding a single allele Aat-3 (1).Great variations were observed in the banding patterns in a population of 46 individuals from selfing the BCF1 between the Cucumis hytivus Chen and Kirkbride and C. sativus L.. Base on the differences in number and location of the bands the individuals were divided into 5 groups, indicating genetic polymorphisms in the population. Comparing the patterns with cucumber, the population produced 2 bands; the average mumber of bands in the population is 7.7, which is 10.0% higher than that in cucumber (7.0). Meanwhile, the activity of bands varies great among the population. The results demonstrated that the genetic base of cucumber has been dramatically widened through the backcrossing with C. hytivus. In addition, the specific POD band (Rf = 0.67) of C. hytivus and C. hystrix was detected in each individual of population, which indicated this band could be a good biochemical marker for monitoring the flow of germ plasm from C. hytivus to cucumber.Phylogenetic relationships revealed by isozyme analysis were similar to that revealed by RAPD. The genetic distance between C. sativus, C. melo and C. hytivus constructed a new triangle relationship in Cucumis. Genetic distance matrices obtained with isozymes and RAPDs, respectively, were closely correlated, r = 0.984. New data was made by combing isozyme data...
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