| Haploid is of great value in breeding and genome research,but low haploid induction rate and low doubling efficiency are the main bottlenecks restricting haploid technology.Therefore,it is of great significance to improve the haploid induction rate by studying the factors affecting the haploid induction rate in cucumber,and to promote the application of haploid technology in cucumber breeding.This study uses five different genotypes of cucumber as female parent with three different genotypes of cucumber materials as male parent to induce haploid offspring in radiation pollen pollination combination of embryo rescue way in spring and autumn respectively.We research the influence of different genotype combinations,season,radiation dose,the location of the seeds in the melon,embryo rescue period and medium types on haploid induction rate,and we used the haploid materials obtained to explore chromosome doubling.The main research results are as follows:1.Effects of different influencing factors on the embryo emergence rate and haploid induction rate after pollination by radiation pollenIn this study,different influencing factors affecting haploid induction efficiency were explored beneficially.The study found that:pollination combinations,radiation dose,embryo rescue period,and medium type have a significant or extremely significant effect on the haploid induction rate and the rate of embryo emergence;season has no significant effect on the haploid induction rate,but it does The impact is extremely significant.In the experiment,the haploid induction rate of combination 7 was 0.50%,which was significantly higher than that of other combinations,and the embryo emergence rate of combination 2 was 0.46%,which was significantly higher than the other combinations except combination 7.And the radiation dose of 175Gy has a significantly higher haploid induction rate and embryo emergence rate than 200Gy.Studies from the embryo rescue period found that the haploid induction rate of embryo rescue at 32-36 days was 0.42%,which was significantly higher than that of embryo rescue at 26-31 days and 37-41 days.Significantly higher than 32-36 days and 37-41 days.As for the medium type,the haploid induction rate and embryo emergence rate in a medium were the highest,respectively 0.36%and 1.61%,which was significantly higher than the other three medium types.2.Ploidy identification and chromosome doubling of haploidChromosome counting and flow cytometry were performed on the obtained haploid material to identify ploidy of regenerated plants obtained by induced radiation pollen combined with embryo rescue experiment;and the haploid plants were further observed for phenotype.Observation of the phenotype of haploid revealed that the leaf length,leaf width,petiole length,stem thickness,and internode length of the haploid of the two varieties in this experiment were all less than diploid,which was significantly different from diploid 0.05)or extremely significant(p value less than 0.01).For the cucumber plants identified as haploid,continue to expand and preserve and double the artificial chromosomes.The chromosome doubling exploration experiment found that the higher the colchicine concentration,the lower the survival rate of the haploid shoot tip material.Treatment with 0.4%colchicine+4%DMSO has a 20%probability of chromosome doubling.In summary,different pollination combinations,radiation doses,embryo rescue periods and pollination periods all have important effects on haploid induction;have less effect on haploid induction.A flow cytometry system suitable for cucumber was explored.Chromosome counting and phenotype observation and identification further confirmed the ploidy verification results of flow cytometry.Under the treatment of 4%DMSO+0.4%colchicine,there is a 20%probability of chromosome doubling. |
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