Study Of Gynogenesis In Vitro To Induce Haploid Plants In Melon

Melon is one kind of world-wide horticultural crops, which hybrid vigor is very significant. But its bred line breeding cycle is long, workload is heavy, this condition seriously hampered the process of melon hybrids breeding. Therefore, shortening the breeding cycle of the bred line can greatly increase the breeding efficiency of melon hybrids. Unpollinated ovary in vitro culture ways and pollen irradiation induced gynogenesis pathway can induce melon haploid plants. Homozygous double haploids will be obtained via chromosome doubling rapidly. Using such techniques can accelerate the choice of melon inbred lines to improve the breeding process. Therefore, discussion on haploid regeneration way has important theoretical and practical significance.In this study,8melon hybrids were used as experimental materials, we focused on melon unpollinated ovaries in vitro culture process, the main impact factors, such as developmental stages of the ovary, pre-culture methods, genotypes, the exogenous hormones and culture conditions of the initiation of gynogenetic and embryoid induction. By adjusting the culture conditions to improve the induction rate, we provide a theoretical basis for melon unpollinated ovary culture in vitro to induce haploid regeneration system. Using melon hybrid M1, M6as experimental materials, we focused on the main impact factors as radiation dose, donor plant genotype in the process of pollen irradiation inducing melon haploid plants.In melon unpollinated ovaries vitro culture process, the result indicated that, the best sampling time of materials was at4-5o’clock pm, and collect ovaries before flowering; the best heat shock preconditioning temperature was30℃and the best cultivated days was3days for the dark pre-cultured; the best culture medium for initiation gynogenesis was MS+0.04mg/L TDZ,30g/L sugar,7.8g/L agar, pH5.8; NAA was not required in the induction process of somatic embryogenesis, This experiment showed that the highest somatic embryogenesis induction rate was with6mg/L2,4-D and2mg/L6-BA in the culture medium, while the best action time of2,4-D was7days. After2,4-D inducing, explants needed transferring to another differentiation medium which didn’t have2,4-D. We found that the best genotype was hybrid M1, which was fit for being induced in the initiation of gynogenetic and embryoid induction process.In the process of pollen irradiation inducing melon haploid plants, the result indicated that, the radiation dose of600Gy was better than300Gy situation in the induction process of immature embryo; Hybrid Ml was more suitable for pollen irradiation to induce melon haploid plants; the basic MS medium without added was selected for the induction medium. We got4regenerated plants of melon hybrid M1, when the radiation dose was600Gy. But the induction rate was very low, only0.64%. We got2haploid plants among that, after we identified ploidy. And the induction rate was0.32%.