Manipulation Of Ploid In Cultivated Cucumbers (Cucumis Sativus L.) And Its Relevant Basic Studies

Different genotypes of cultivated cucumbers (Cucumis sativus L.) were used in the present paper to study ploidy manipulation. Cucumber haploids were obtained via irradiated pollen pollination technique. Doubled haploid/diploid plants were regenerated through ovary culture. Using colchicines treatment on germinating seeds induced tetraploids. Comparative studies on morphological traits and some biochemical parameters were carried out between diploid "Jinlvsihao", haploid and tetraploid derived from the diploid.1. Haploid cucumbers induction via irradiated pollen pollinationShedding ability and viability maintenance of the irradiated pollens was the prerequisite to the successful experiment. The results from short time storage of anthers under eight designed conditions at room temperature (25-27℃) and 4℃ showed that the anther opened well at room temperature, and treatments 2 (conserved in petri dishes under room temperature) and 8 (conserved in humid petri dishes under room temperature) were much better than the other treatments. The conditions good for pollen shedding were also good for germinating. Multiple comparison analysis among germination rates of treatments2, 8 and control showed no significant difference between treatment 2 and control, but both treatment 2 and control were significantly higher than treatment 8. Anthers that irradiated in the morning one day before anthesis were used to test the best storage method and the results proved that the treatment 2 was good for short time storage of irradiated cucumber anthers.The experiments on cucumber haploids induction by γ-irradiated pollen techniquewere carried out both in spring and autumn seasons in 2003. Totally 123 pollinating combinations were made with 35 genotypes as female parents and 10 genotypes as male parents. And 51 haploid embryos from 18 different maternal genotypes were successfully recovered through embryo rescue on solid or on liquid media plus vibrating. The percentages of haploid embryo production were from 0.38% to 50.00%. The results showed that there was no significant influence of irradiation season and male flowers developing stage when being irradiated on fruit setting and haploid embryo production. The in vitro germination rates of the pollens grains after irradiation were significant decreased but limited influences of dosage were found in the used doses. Heterozygosity of the male genotypes showed no more effects on fruit setting rates and haploid embryo rates, while the female cucumbers of Chinese heterozygosity ecotypes benefited the haploid embryo production. And pollination combinations were found to have great influence on fruits setting and haploid embryos production.Cucumber haploid embryos were cultured on MS media supplemented with 0.2 mg·L-1 6-BA for plantlet direct recovering and 2.2 mg·L-1 6-BA for organogenesis. The results showed that the rate of embryos into plantlets directly was much higher than the rate of embryos for organogenesis. The organogenesis was occurred which indicating haploid doubled through in vitro culture was promising. Quantitative tests and qualitative observations were carried out between haploid and diploid plants. Haploid embryos were found to develop slower and the plantlets were slim and fragile. Haploid plants grew much slowly and had slim stems; smooth leaves with little drape, smaller, rather narrow and separate female petals. The male buds of the haploid degenerated before anthesis or flowered with abnormality traits and empty anthers without pollens. The fruits were smaller containing almost empty seeds.Meiotic chromosome behaviors and the subsequent viability of male and female gametes in monohaploid plants (H2) were investigated comparatively using the monohaploid plants as materials. Chromosomes were mainly in the form of univalent with a configuration formula 2n = x = 6.72 I +0.1411+ 0.03 III at metaphase I. However, bivalents including circle- and rod- ones, were also detected at 10.3% PMCs at metaphase I. Chromosomes were distributed in a form of (3+2+2) at 35% PMCs at metapha...