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Exploring Genetic Diversity Of Dioscorea Zingiberensis And Diosgenin Content

Posted on:2008-11-16Degree:MasterType:Thesis
Country:ChinaCandidate:Y H LiFull Text:PDF
GTID:2120360215999679Subject:Botany
Abstract/Summary:PDF Full Text Request
Amplified Fragment Length Polymorphism (AFLP) markers was used for the first time to study the genetic diversity and genetic structure of 30 Dioscorea zingiberensis individuals which belongs to five populations transplanted in Yangling Germplasm Resources Nursery. Meanwhile, the paper analyzed populations of diosgenin content of Dioscorea zingiberensis of the individuals and then revealed their genetic diversity. The conclusions were drawn as follows:(1) Selected nine pairs of AFLP as primers, 14,698 of the visible band had been detected out, of which 12,628 were polymorphic. On the average each primer combination could detect 230 polymorphic bands. The polymorphism rate was 85.92%. The highest E-ACT/M-CTC polymorphic composition rate was 94.46%, and the lowest was 74.75%. The coefficient similar scope was 0.548-0.778. The results showed that AFLP could detect very rich polymorphism.(2) The genetic diversity among groups and within groups of the five Dioscorea zingiberensis populations were detected out by the use of 9 pairs of primers. The genetic diversity of the Five Dioscorea zingiberensis populations on the species level (Ht) was 0.2331. The genetic diversity of groups (Dst) was 0.1123. Genetic diversity within groups (Hs) was 0.1208%. Within groups accounted for 51.82% of the whole genetic diversity, the genetic diversity of between groups accounted for 48.18%, Genetic diversity within groups was higher than that of between groups of diversity.The genetic differentiation index called Nei (Gst) was the most commonly used index to measure genetic differentiation of population, which showed the genetic variation part among populations of the total.The percentage of genetic differentiation was 0.4827.It indicated there wre certain degree of genetic differentiation five Dioscorea zingiberensis populations. The gene flow (Nm) indicated the exchange degree of gene between groups. The Nm gained in this paper was 0.5418 which showed that the five populations were at the low level of gene flow and there were few exchange between populations.(3) The NTSYS-pc2.11F software and UPGMA cluster method were used to analyze the data and AFLP fingerprint graphs had obtained. The graphs showed that the genetic distance between the different samples of Dioscorea zingiberensis was 0.222~0.452. From that figure, the 30 Dioscorea zingiberensis individuals could be divided into five groups at 0.70 similar coefficient level. The 5 groups were Baihe, Langao, Hubei, Chengkou of Chongqing, and Qingcheng of Gansu populations respectively.Genetic identity and genetic distances were the two mirror indicators to measure the genetic relationships on positive and negative point of view. Genetic distances indicated the relative lever among populations. In comparing with the genetic distance from Langao population, Baihe (0.0343) was most close, Hubei (0.0458) was at the second, Chongqing (0.1787) was at the third, and Gansu (0.2024) was the longest. It showed that the Langao population was more similar with Hubei and Baihe populations.Cluster analyses were performed by using NTSYSpc versio2.11F and POPGENE 1.32 software to study and cluster the genetic identity of Dioscorea zingiberensis populations, and built out cluster chart. The results of both groups clustering and individual one were almost the same shape. The nearest genetic distance between Baihe and Langao populations gathered together first, and then Hubei and Chongqing populations, and the Gansu populations was a separate one from the clustering result of both soflwares, it could be seen that the genetic similarity of Dioscorea zingiberensis was very rich, and they were in accordance with the geographical distances between clusters.(4) Good environmental conditions and suitable cultivation methods could improve the diosgenin content in the tuber of Dioscorea zingiberensis. The diosgenin content in Dioscorea zingiberensis at Yangling national germplasm garden was significantly higher than that of national average. Besides, diosgenin content increased after cultivation. At the same time, we found from the statistic result that the tubers with the coarse fiber contained the highest diosgenin, and the tubers with the medium and less quantity of fiber contained higher diosgenin.The tubers with three branches of Dioscorea zingiberensis contained the highest diosgenin. The diosgenin content of the five Dioscorea zingiberensis populations from lowest to the highest were in the sequence order as Gansu, Hubei, Chongqing, Baihe of Shaanxi and Lan-gao of Shanxi populations. We also found that the diosgenin content was not very close in relationship with the plant weight both of ground and underground. Based on the analysis data of original primer amplified bands, the band with 86 size in electrophoresis map would be the one that contains the gene controlling diosgenin formation.
Keywords/Search Tags:Dioscorea zingiberensis, AFLP genetic diversity, Genetic Structure, Germplasm resources, diosgenin
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