The Study On Tissue Culture Of Gerbera Jamesonii And Ploidy Identification Of Unfertilized Ovule Culture Seedlings

Gerbera jamesonii is a herbaceous perennial flower, which belongs to the Asteraceae family. It is an important cut flower in domestic and international markets. In recent years, it has a rapid development in the market of potted flowers. Nowadays, tissue culture and rapid propagation techniques have been increasingly used in the production of G. jamesonii, but the regeneration ability of adventitious buds varies among different varieties. Moreover, the development of G. jamesonii industry is severely hampered because long-term vegetative reproduction leads to some serious problems including severe diseases and insect pests as well as ornamental characteristics degradation in production. Therefore, obtaining homozygous genotype in G. jamesonii from haploid culture and chromosome doubling will lay the foundation for heterosis utilization breeding and cultivation of new varieties.In this study, different varieties of G. jamesonii are used for exploring the in vitro induction condition of adventitious bud and suitable formulations for growth of unfertilized ovules in vitro. The ploidy of plants with in vitro gynogenesis was also identified. The main results are as follows:1?Through four factors and four levels orthogonal experiment, suitable media for ‘Huoyan' and ‘Huancai' which is used for tissue culture to induce bud are screened out. Results showed that the media?MS+ BA 10.0 mg/L+ KT 3.0 mg/L+ NAA 0.2 mg/L? can significantly promote the budding for ‘Huoyan'. The adventitious buds induction rate of receptacle explant can reach up to 40 % after 30 days of culture. The bud regeneration rate is even higher and up to 55 % in media?MS+ BA 7.0 mg/L+ KT 1.0 mg/L+ NAA 0.4 mg/L? after 60 days of culture. Suitable medium formula for bud regeneration of ‘Huancai' is MS+ BA 7.0 mg/L+ Ag NO₃ 1.0 mg/L+ NAA 0.3 mg/L and MS+ BA 13.0 mg/L+ KT 5.0 mg/L+ NAA 0.3 mg/L. The adventitious bud induction rate of receptacle explant is up to 20 % after 60 days of culture.1³ mg/L Ag NO₃ can prevent bud regeneration in G. jamesonii tissue culture condition. Compared with medium without Ag NO₃, the regeneration rate of adventitious buds in ‘Huoyan' is decreased by 23.75²6.25 % and 26.25³6.25 %, after 30 and 60 days of culture, respectively. While in ‘Huancai' it is decreased by 1.25³.75 % and 5.00¹3.75 %, after 30 and 60 days of culture, respectively.2?AgNO₃ can significantly promote the growth of unfertilized ovules of G. jamesonii in vitro culture and reduce the degree of browning, but different varieties need different suitable concentration of Ag NO₃. The rate of ovule swelling reach the highest and the rate of browning decrease to minimum when 1.0 mg/L Ag NO₃ is contained for ‘Huancai' and ‘HH-5'. The swelling rate is 44 % and 20 % while browning rate is decreased by 36 % and 18 %, respectively. Suitable Ag NO₃ concentration for ‘Caihong' is 1.5 mg/L, under which condition ovule swelling rate increased by 5-fold and browning rate reduced by 16 %. Suitable Ag NO₃ concentration for ‘Fenxiu' and ‘Huoyan' is 0.5 mg/L. At this concentration, ovule swelling rate increased by 4-fold and 8.5-fold, and browning rate decreased by 6 % and 75 %, respectively.3 ?The experimental observation including chromosome number, morphology, chloroplast number of leaf abaxial epidermis stomatal guard cells, size and number of leaf abaxial epidermis stomatal cells was conducted on plants derived from unfertilized ovule of ‘Caihong', ‘Revolution Red' and ‘HH-5'. Compared to the diploid plants with 50 chromosomes, the chromosome number of all three experimental plants is 25, indicating that they are gynogenetic haploid. Compared to the diploid, haploid has smaller and unsmooth blade, short and thick petiole, and shrinking plant type. The ratio of chloroplasts number of abaxial epidermal guard cells of haploid to diploid in ‘Caihong' and ‘Revolution Red' is 2.11: 1 and 1.81: 1, respectively; the ratio of the number of pores is 1: 1.54 and 1: 1.89; the ratio of stomatal length is 1.6: 1 and 1.3: 1; the ratio of the width of the stomata is 1.43: 1 and 1.56: 1, which is in line with the principle of ploidy. It can be used as an effective means for the identification of gerbera ploidy.