| Cucumber ( Curcumas saliva L.) is an important vegetable crop. Its sex phenotypes includes several types, and the genoecy plays an important role in cucumber heterosis breeding. Gynoecy breeding is one of the main breeding aim in cucumber breeding. Researches about its sex determination have an important value for the basic theoretics of plant development biology. Based on different ecological type materials of cucumber, F1, F2, BC1 and BC2 population were constructed, and the inheritance law of sex was study; RAPD and AFLP markers linked to gynoecious loci were attained, these markeres could be utilized for marker assist selecting (MAS) of cucumber gynoecious lines; ACC synthase gene was cloned by the method of PCR technique, and its expression level was studied in different organs including root, stem, leaf, male flower bud and female flower bud, and its expression was studied also when female flowers were induced with ethyphon; Isozyme technique was employed to explored the relationship between isozyme change characterization and sex expression. The details were described as follows:1. F1,F2, BC1 and BC2 populations from cross of gynoecious and monoecious cucumber of differental ecological types were employed to analyse the inheritance character of cucumber sex, and the effects of photoperiod and tempreture on sex phenotype and its inheritance. The results showed that the inheritance of gynoecious in cucumber was controlled by one dominant gene, and gynoecious was dormant on monoecious. When the loci of gynoecious was in homozygous, the gynoecious phenotype was stable, and was not effected by the photoperiod and tempareture. But if the loci of gynoecious was in heterozygous, the expression of gynoecious might be relative with the genetic background. Some ecospecies had stable gynoecious phenotype, but other had sub-gynoecious phenotype with few male flower in early days in few plants according to the growing season. Accordingly, the gynoecious in cucumber was controlled mainly by one key gene, and there was also other genes that could modify gynoecious expression by the signal of photoperiod and tempreture.2. The sex separate progeny from the cross between Japanese gynoecious and Chinese cucmber were employed to study the molecular markers linked to the sex determination genes of cucumber with RAPD technology. With the method of BSA, 300 randomlyselected 10bp primers were used in PCR amplification of the DNA pools from gynoecious and monoecious cucumber, respectively, and polymorphism were found in five primers in three replications. Those polymorphic primers were used to detect the individual samples with different sex phenotype, a band of 1000 bp was amplified specifically in DNA from the gynoecious plants tested. This band is absent in the monoecious plants and marked as B11-1000- 12.2 cM of the genetic distance to gynoecious loci was computered with a software of MAPMAKER(version 3.0)3. hi the present study, selfed gynoecious cucumber 'Delta star' and monoecious cucumber 'Beijing Jietou' were used as parents to make F1 and then selfed to get F2 sex segregated population. Gynoecious and monoecious DNA pools were developed separately using bulked segregant analysis (BSA). Amplified fragment length polymorphism (AFLP) technique with 64 primer combinations were employed to find the polymorphisms between these DNA pools, and five primer combination of AA/CAT142, AG/CAA265, AT/CTC260, TA/CTG263 and TG/CAC234 were found polymorphism between both gene pools. These markers were testified with individual DNA of the F2 population. Only the primer combination of TG+CAC was found to amplify a specific fragment of 234bp in the individual gynoecious plants. Linkage analysis using the software of MAPMAKER (version 3.0) indicated its genetic distance to the gynoecious loci was 6.7 cM, and this AFLP marker was designed as TG/CAC234. This band was collected and sequenced to synthesize a sequence-characterized amplified region (SCAR) primer. The primer was used to amplify the individual DNAs of t...
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