Study On In Vitro Culture Of Un-pollinated Ovary In Watermelon (Citrullus Lanatus)

Watermelon cultivation in China is very extensive,large demand.However,the genetic base of watermelon is narrow,and the breeding cycle of traditional watermelon is limited by its long cycle,heavy workload,unstable genetic traits and difficult to obtain target traits.Watermelon un-pollinated ovary in vitro culture pathway can produce haploid or double haploid plants,and then get pure inbred lines,shorten the breeding cycle.In this experiment,four subspecies of watermelon hybrids were used as experimental materials,and the un-pollinated ovary was used as explant.Mainly discussed the influence of ovule enlargement rate on dark culture time,sodium hypochlorite solution concentration and disinfection time,different basic medium and TDZ,NAA,BA And KT different concentrations and other factors.And explored the main factors affecting the regeneration of plantlets induced by in vitro fertilization of watermelon such as genotype and induction medium and the ploidy of the regenerated plants was identified.The aim of this study is to further improve and optimize the in vitro culture technology of watermelon non-pollinated ovary,so that the technology is gradually mature and applied to the breeding of watermelon.The main results of the study are as follows:1 The concentration of sodium hypochlorite solution and the disinfection time had some influence on the induced swelling rate of ovule.The results showed that10% sodium hypochlorite solution disinfected for 10 min had the best effect on ovule enlargement.2 The length of darkening time affected the effect of ovule enlargement,although the enlargement rate of ovule was not significantly different at 7d and 14 d,but it was significantly higher than that of ovule without darkening.Therefore,the darkening time could be increased to improve the ovule expansion rate.3 The change of nutrient content in the basic culture medium also affected the swelling rate of the ovule.The content of organic matter in the basic culture of M2 was higher.The results showed that the ovule induction effect on M2 medium was the best,and the regenerated plants were obtained on M2 medium.4 The orthogonal design method was used to screen the different combinations ofhormones,which indicated that the hormone was necessary for in vitro culture of watermelon non-pollinated ovary.When the concentration of TDZ was 0.04-0.08 mg /L and the concentration of NAA was 0.5mg / L,BA and KT concentrations were low,and the effect of ovule enlargement was better.On MS + 0.5mg / L NAA + 1.0mg /L6-BA + 0.5KT differentiation medium,it is conducive to induce the expansion of the ovules to differentiate embryoids.5 In the modified induction medium M2 + 0.02 TDZ + 0.5 NAA +0.56-BA,the embryogenic bodies were induced and the regenerated plants were obtained.6 The genotype of watermelon had a certain effect on the inducible embryoid induced by in vitro culture.The induction rate of embryogenic body of three different genotypes was different,the embryo induction rate was 1.67% and the lowest Is 0.7 Four regenerated plants were obtained and the regenerated plants were identified by flow cytometry.The results showed that one plant was tetraploid plants and the other three were haploid and diploid fit plant.