Synthesis Of Tetraploid And Relevant Studies On Different Ploidy Materials In Cucumber Plants (Cucumis Sativus L.)

Eight genotypes of autotetraploid cucumber plants were produced by treating cultivatedcucumbers (Cucumis sativus L.) with colchicines. Mature seeds of tetraploid 'P01' were gotwhen self-pollinated. Cucumber haploids were obtained via irradiated pollen pollinationtechnique. Doubled haploid/diploid plants were regenerated through ovary culture.Comparative studies were carried out on meiotic chromosome behavior and fertility ofhaploid and (/or) autotetraploid cucumber plants, as well as genetic diversity betweendiploid "JinlvNo.4", haploid and tetraploid derived from the diploid.1. Synthesis of Tetraploid and Its Fertile Stability in Cucumber plantsEight genotypes of tetraploid were produced by treating germinated seeds of cucumber(Cucurnis sativus L) with 0.4ï¼…colchicines for 4h under room temperature, respectively,mature seeds were obtained when autotetraploid 'P01' were self-pollinated.The new tetraploid was similar to the original diploid in morphology traits, such as thenumber of lateral branches was smaller, length of petiole shorter, size of the leaves andflowers larger, as well as four-sized pollen grains were observed in male flower. But therate of four-sized pollen grains was relatively higher. At the same time, the staining abilityand germination rates of tetraploid pollen grains upgraded greatly compared to the formertetraploid. It showed that fertility was higher in new autotetraploid cucumber plants.2. Studies on Meiosis and Fertility of Monohaploid Cucumber PlantsThe aim of the experiment is to investigate the meiotic chromosome behavior incucumber haploid plant (2n=x=7). Meiotic behavior was studied by using three genotypehaploid plants as materials. Compared with diploid, chromosomes of monohaploid weremairdy in the form of univalent with an average configuration formula2n=x=6.22â… +0.37â…¡+0.01â…¢in three genotype haploids. Bivalent were observed in32.85ï¼…pollen mother cells (PMCs). There were two to four chromosomes owing nucleolus organizer region (NOR) around the nucleolus at Diakinensis. There were three types ofchromosome partioning at Metaphaseâ… . Seven chromosomes were mainly divided into 4and 3 chromosomes as a whole at Anaphaseâ… , as well as the lagging, lingering anddisrupted chromosomes were found frequently. Some chromatids were divided atAnaphaseâ…¡. Chromosome behavior was quiet different from diploid in haploid cucumberplant. Some chromosomes have homologous parts in haploid genome of cucumber plant.The aim of the experiment is to investigate the fertility of male and female gametes inhaploid cucumber plants (2n=x=7). The viability of male and female gametes was studiedcomparatively by using three genotypes haploid plants as materials. Pollen grains wereunstainable in 'H1' haploid; 2.26ï¼…pollen grains were stainable and ovary could developinto fruit but embryo abortion in 'H2' haploid; Female gametes were fertile and coulddevelop into cytolendenary embryos. Plantlets could be obtained by embryo culturing in'H3' haploid. Uniad to nonuplad came into being after meiosis and the ration of tetrad wasthe highest in three genotype haploids. All the chromatids of seven chromosomes weredivided at Anaphaseâ…¡in 'H3' haploid and abnormal spindle, octagon appeared.Simultaneously, the rations of dyad and triad were 19.37ï¼…and 19.72ï¼…, equaling to thetetrad', as well as shape were different from H2'. The viability of male and female gametesvaried in different genotype haploid plants. The fertility might be the result of abnormalspindle appearance when all the chromatids of seven chromosomes being divided atAnaphaseâ…¡.3. AFLP Analysis of Genetic Diversity among Different Ploidy Cucumber PlantsAnalysis was conducted with different ploidy cucumber plants, including haploid,diploid and autotetraploid developed from the cultigen 'JinlvNo.4'. AFLP molecular markerwas used. Thirty-five primer combinations were employed on different ploidy and a total of2188 bands between 60-500 bp were observed. Results showed that bands of differentploidy in cucumber amplified were not apparently different by 22 primer combinations. Therate of polymorphism sites was only 0.92ï¼…. Bands of haploid and/or autotetraploid weremainly absent but present in diploid in polymorphism sites. A special band forautotetraploid was amplified. There were present or absent of specific bands of haploid andautotetraploid compared to the diploid.