Study On Tetraploid Induction And Characteristic Analysis Of Saintpaulia Ionantha

Saintpaulia ionantha is a perennial evergreen herb flowers in Saintpaulia of Gesneriaceae. It is a plant produced originally in Tanzania of East Africa, which likes the warm and humid climate.Saintpaulia ionantha has high ornamental value and economic value because of its brightly color variety, beautiful leaf type,and long flowering period and it is an excellent potted flowers used to beautify environment.In this experiment,the S. ionantha leaf petals were used as materials.Firstly,established rapid propagation system which made the foundation for saving the species, improvement and factory production.Then used colchicine to induce polyploidy and explore the most suitable concentration of colchicine treatment and time which is to obtain new varieties with varieties with the view of higher value and excellent resistance. Compared for the morphological characteristics and resistance between tetraploid and diploid of S.ionantha.Finally,analysised the differences of DNA methylation level and pattern between the tetraploid and diploid so as to discuss preliminary autopolyploid gene expression regulativemechanism.The main results were as follows: 1.Established rapid propagation system with the diploid plants and obtained the best sterilization of explants:selected young leaves as explants In the March to April. The explants were dipped in the scour 10 minutes and washen 20min by tap water, then sterilized 10 seconds by 75% alcohol and 7 min by 0.1% HgCl2, rinsed 4-5 times by sterilized water.The best medium for primary culture was MS+0.5 mg/L 6-BA+0.1 mg/L NAA,and the differentiation rate was 60%; The best medium for proliferation was MS+0.3 mg/L 6-BA+0.04 mg/L NAA,and the The best medium for multiplication coefficient was 10.0; The optimal rooting medium was 1/2 MS+NAA0.2mg/L,and the rooting rate was 95%.2. Used immersion method and the mixed culture method for tetraploid induction by colchicines, and the result indicated that:The most effectively induction of immersion method was Soaking in 0.3% colchicine for 8 d, and the induction rate reached 20.0%,homozygote induction rate reached 15.0%;The most effectively induction of immersion method was Soaking in 0.2% colchicine for 24 d, and the induction rate reached 10.0%,homozygote induction rate reached 5.0%;In contrast, the immersion method is more beneficial to the induced tetraploid of S. ionantha.3.Compared morphology, stomata and guard cell properties of tetraploid and diploid of S. ionantha. and the result indicated that:The tetraploid plants grow robuster than diploid and the leaves of tetraploid plants were thicker, wider, smaller leaf, thicker stems, deepener color shorter internode, stronger rooting system. Petiole and stem were thicker.The leaves thickness, length and width of tetraploid were 175.0%,115.45%,123.66% of diploid respectively. The leaves index became smaller. The guard cell length,width of guard cells,the number of chloroplast, Chlorophyll content of tetraploid leaves increased significantly,were 144.81%, 132.72%,190.48%,154.1% of diploid. The stomatal density declined,was52.62% of the diploid. 4. Compared for the resistance between tetraploid and diploid of S. ionantha, and the result indicated that:The electrolyte leakage rate of tetraploid was lower than the diploid plants In the same low temperature;The leaf water retention of tetraploid was higher than diploid,was 138.85% of diploid; Permeability and cell damage rate were lower than the diploid,were 50.93 and76.24% of diploid respectively. It explained that cold,drought and heat resistance of tetraploid are stronger than diploid of S. ionantha.5.Compared for the DNA methylation analysis between tetraploid and diploid of S. ionantha, and the result indicated that:Compared with diploid, the total methylated ratios,full methylated ratios of tetraploid are decreased,and hemimethylated ratios of tetraploid is increased and also has four kind of different methylation types.compared with the diploid, genome DNA methylation level and pattern of tetraploid was significantly different. These changes may induce the activation and silencing of certain genes, and caused epigenetic changes.