| The fine germplasm is the guarantee of the stability and controllability of the Traditional Chinese Medicine quality, the hybrid varieties can provide stable, uniform and good-resistive germplasms with high yield and good quality for the medicinal plant production, but there is still not such a variety applied in the production in China at present. In this paper, Platycodon grandiflorum was studied to explore the method and technology of using heterosis in sexual reproduction medicinal plant, which is to lay the foundation for the breeding of the hybrid varieties of P. grandiflorum which are special-purpose for medicinal materials or concurrent for medicine and food.1. we confirmed P. grandiflorum was highly genetically self-compatible, and corrected the wrong understanding that P. grandiflorum was self-incompatible. Low fhictiflcation percentage with self-pollination attributed to the difference of maturing period of the pistil and stamen, as well as the short pollen life-span of P. grandiflorum. while the fructification percentage and index of self-compatibility were to reach respectively 62.7% and 54.6%. The results were further confirmed by that the emergence of pollen grain from the own flower, other flowers in same plant or other plant and the growth process of pollen tube were observed by fluorescence microscope technology after artificial pollination. Pollen grain massively sprouted about lh after pollinating in chapiter, and pollen tube reached the ovary in 24h.2. Discovering the P. grandiflorum male sterility materials for the first time, wefounded out that such male sterility may stably inherit and maintain, which laid the foundation for using male sterility to cultivate hybrid variety. The anther was thin and small and pollens were undynamic and rarely viable, while its female reproductive organ was normally, and could accept the external pollen to seed in sterile material. The morphology and economical traits of sterile materials were similar with natural material, and the characteristics of male sterility were stably inherited. The proportion of fructification and sterility in testcross descendant was below 1: 3, or above 1: 4. The former showed the characters of genie male sterility (GMS) type, such as JA78, and the latter cytoplasm male sterility (CMS) type, for instance JA162. The testcross descendants of the combination of JA162 with JA71 or JA88 were nearly sterile, which were hopefully bred into male-sterile line and maintainer line.Paraffin slice result showed the abortion period and mechanism of GMS and CMS were different. The former didn't form the microspore after tetrad period, and the latter was little quantity of the pollen mother cell. The deductions was also confirmed that P. grandiflorum male sterility material existed two kind of abortion types, and CMS displayed the cytology characteristic of thorough abortion.3. The genetic controllability pattern of P. grandiflorum stem color and flower colorhad basically been mastered, and the connection relations of the stem color, flower color and seed shell color were expounded. The genetic analysis indicated stem color (stem point color and hibemaculum color), flower color, and seed shell color, were taken as the marker characteristics of P. grandiflorum hybrid breeding. The correlation of three organs colors and flower color heredity were as follows.Seed shell colorFlower colorStem colorW*—purple flower (wildness type). W"—pink (recessive mutant type).W—white flower (recessive mutant type). The flower colors of variousblackgene type were as follow:------_____PurpleW* W+---------purple flowerbrown ^^"W* W---------purple flowerS// pink ^W* W---------purple floweryellow and black //V V--------pink flower/^~~~~-~^ whitegrrmW W--------purple flowerbrown and green /W W &VcFlower color was quality properties, and the pink flower was not the medium type of purple flower and white flower. Three kind of controlling flower color gene was multiple allelic gene. Both pink flower and white flower were recessive mutant types. The stem color was controlled by single dominant-recessive major gene. The green stem that was opposite to the purple stem, was recessive, and many modificatory genes influence the appearance of purple stem that exist continuously transitional form. The seed shell color was quantity properties, and its heredity background was complex.4. Analysis of genetic diversity indicated the primary cultivated germplasms of P.srandiflorum were promiscuous and heterogeneous in China. The genetic differentiation between different habitats was obvious, and the diversity of morphological characteristics and economic characteristics between germplasms was rich, which could provide the profuse genetic material for the selective breeding of inbred line. The inbred lines of GSNH2-W(white color) and GSNH3-M(purple color) would be cultivated the flower color varieties used as both medicines and foods, moreover, GSNH3-W would be cultivated to be special medicine varietie, or took as good parent material.Analysis by RAPD markers indicated the number of P and Ht among cultivation germplasms were AT>AB>NOSZ, and the dendrogram from Ihe Cluster of UPGMA and SPSS of the RAPD genetic distance showed the good classification of all germplasms. The karyotype of 7 germplasms showed there was twain chromosome with satellite on the short arm of chromosome in karyon of 7 germplasms. There were 3 karyotype formula in 7 germplasms, namely 2n=2x=18=14m+4sm (2SAT), 2n=2x=18=14m(2SAT)+4sm, 2n=2x=18=18m (2SAT).The diversity analysis of morphological characteristics showed the average diversity index and the variation coefficient of one-year-old germplasms respectively was 1.7 and 31.67%. The average diversity index of perennial germplasms was 1.79, and the variation coefficient of three-year-old and four-year-old germplasms respectively was 25.81% and 25.29%. The appraisal data of economic characteristics indicated various germplasms could be used in the different breeding direction.5. The analysis result of heterosis indicated the majority of characteristics P. srandiflorum existed in the combination of over-parent heterosis. there also were 2 combinations with over-parent heterosis in the 19 combinations of total soapnins content. The fact that the combining ability of NH3, NH2 and JA were better, indicated the inbred lines of pink flower and white flower selected and bred from both NH3 and NH2 would be provided with good prospect in selecting hybrids inthe future.6. The flowering dynamics of single flower, one-year-old germplasms, the single of perennial germplasms and the community of various germplasms were showed. P. grandiflorum planted in Hainan province could grow normally, which indicated two generations of P. grandiflorum in one year is possible.In this paper, we carried on an investigation in the key questions that heterosis use needed to solve for the first time in sexual propagation plants of Traditional Chinese Medicinal. This study laid the good foundation for selecting and breeding hybrid variety of P. grandiflorum, and that the application prospect of also was broad. At the same time, it existed important reference value to develop similar research for other Traditional Chinese Medicinal plants, and enriched the content of genetic breeding of Chinese medicinal plant. |
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