Dissertation > Excellent graduate degree dissertation topics show

Analysis of Genetic Diversity in Pear (Pyrus) and Cherry (Cerasus) Germplasm Using DNA Molecular Markers

Author: LuJuan
Tutor: WuJun
School: Nanjing Agricultural College
Course: Pomology
Keywords: Pear (Pyrus L.) Cherry (cerasus) SSR EST-SSR SRAP Genetic polym-orphism Genetic relationship
CLC: S661.2
Type: Master's thesis
Year: 2010
Downloads: 29
Quote: 0
Read: Download Dissertation

Abstract


In this thesis, genetic polymorphism of different germplasm in Pyrus and Prunus Cerasus were analyzed by using SRAP, SSR, and EST-SSR markers. The primary results were as followins:(1) Eight Simple Sequence Repeat markers derived from expressed sequence tags (EST-SSR markers) of apple were selected for analysis their general application on levels of genetic diversity among 48 cultivars in pear (Pyrus). Results showed that eight EST-SSR primer pairs gave an amplification product when tested on all pear cultivars, and the size of amplification bands were similar to those of apple. In this study,140 gene locus were screened by all EST-SSR, of which 129 (92.14%) were polymorphic, and different cultivars could be distinguished successfully. Therefore, EST-SSR markers developed from apple (Malus pumila) showed high transferability in pear (Pyrus), and it would be suitable for application in germplasm evaluation and genetic relationship analysis of pear. Based on polymorphism revealed by EST-SSR markers, UPGMA cluster analysis was performed by soft NTY-SIS-pc2.01, the clades formed two populations, oriental and occidental population, at the dice coefficient of 0.62.Pyrus bretschneideri Rehd.,P.ussuriensis Maxim.and P.pyrifolia Nakai.originated in China interveined each other and could not form group independently.(2) Genetic diversity and polygentic relationship of 150 cultivars of pear, which belong to Pyrus bretschneideri Rehd., Pyrus pyrifolia (Burm.f.) Nakai, Pyrus ussuriensis Maxim., Pyrus communis L., Pyrus sinkiangensis Yii.,Specii salbatice and inter-specific hybridization, were analyzed by SSR markers in this paper.25 primer pairs produced a total of 407 alleles, and each primer pair could detect 5-25 alleles, of which 390 were polymorphic with a polymorphism percentage of 95.82%. Heterozygosity ratio was 0.4 to 0.7, and the Dice’s similarity coefficient between cultivars ranged from 0.67 to 1.00. The dendrogram generated from all the 150 accessions by unweighted pair-group method of arithmetic analysis (UPGMA) cluster analysis clearly distinguished Occidental pears from accessions of East Asia.Cultivars of Pyrus communis L. and inter-specific hybridize with Pyrus communis L. clusted into the Occidental clade. The clade of Oriental pear formed two main groups, seven subgroups, at the dice coefficient of 0.685. Pyrus bretschneideri Rehd.,P.ussuriensis Maxim.and P.pyrifolia Nakai.originated in China interveined each other, and did not group independently. Chinese Pyrus pyrifolia (Burm.f.) Naka. showed the most abundant genetic diversity, followed by Pyrus bretschneideri Rehd..cultivars from Japan and the Chinese Pyrus pyrifolia (Burm.f.) Nakai. demonstrated a high degree of genetic relationship, and there is no separate group. Most of new cultivars and selections showed the genetic relationship closing to female or male parent.(3) Genetic diversity of 300 pear cultivars was analyzed by using SRAP markers. Twenty SRAP markers detected 210 alleles, with an average of 10.5 alleles per locus, of which 192 (91.43%) were polymorphic. Moderate genetic diversity were identified in these cultivars when appraised by Nei’s gene diversity and Shannon’s Information index with the value of 0.2788 and 0.4250. Twenty pairs of primers could distinguish all of the pear cultivars except the mutant. Based on polymorphism revealed by SRAP markers, UPGMA cluster analysis was performed by soft NTYSIS-pc2.02, the clades formed two populations, oriental and occidental population, at the dice coefficient of 0.66. Cultivars of Pyrus communis L. and inter-specific hybridize with Pyrus communis L. clusted into the Occidental clade, formed five main groups. The clade of Oriental pear formed six main groups, eleven subgroups. Pyrus bretschneideri Rehd., P.ussuriensis Maxim. and P.pyrifolia Nakai. originated in China interveined each other, and did not group independently; cultivars from Japan and the Chinese Pyrus pyrifolia (Burm.f.) Nakai demonstrated a high degree of genetic relationship, and there is no separate group. Most of new cultivars and selections showed genetic relationship closing to female or male parent.(4) Three different genotypes germplasm of cherry which showed distant relationship were used in this study. The concentrations of Mg2+,dNTPs,Taq DNA polymerase, primers and DNA template which affect the SRAP-PCR reactions were optimized in order to establish the SRAP molecular marker system in Cherry. The optimum system was established as follows:template DNA 75ng, dNTPs 0.2mmol.L-1, Mg2+2.5mmol.L-1, primer 0.3μmol.L-1, Taq polymerase 1.0U, the total reaction volume was 20μl. Amplifications were carried out on 45 samples with eight primer combinations using this optimum system,227 steady and reliable bands were amplified, of which 192 (84.6%) were polymorphic. UPGMA cluster analysis was performed by soft NTYSIS-pc2.01, the clades formed including two groups at the dice coefficient of 0.52, namely sweet cherry (P. avium L.) and Chinese cherry (P. pseudocerasus L.). The genetic similarity coefficient of the 45 accessions ranged from 0.52 to 0.98. The lowest genetic similarity coefficient existed between sweet cherry and Chinese cherry, it showed that the genetic background of two groups differed from each other. The high similarity coefficient existed among different cultivars belonging to the same groups. The cluster results revealed by SRAP showed that the relationship of cherry germplasm was related to geographic distribution and originals.

Related Dissertations

  1. Development of EST-SSR Primers and Application in Analysis of Genetic Realtionships in Tree Peony,S685.11
  2. SRAP and SSR molecular markers of pink flower Dendrobium genetic diversity and population genetic structure,S567.239
  3. Study on Inheritance and Molecular Markers of Resistance to the Root-Knot Nematode (Meloidogyne incognita) in Cucumber Introgression Lines,S436.421
  4. Screening of Molecular Markers for Downy Mildew Resistance Introgression Line of Cucumis Hystrix-C. Sativus and Analysis of Programmed Cell Death,S436.421.11
  5. Study on Heterosis and Genetic Basis of Soybean,S565.1
  6. Characterization of Population Structure and Linkage Disequilibrium of Chinese Soybean Landerace Population and QTL Association Analysis of Traits Related to Breeding for Soybeans,S565.1
  7. Isolation, Expression, SSR Marker Analysis of Genes Related to Parthenocary of Cucumber,S642.2
  8. Studies on Genetic Diversity and Phylogenetic Relationship of Dendranthema and Its Related Genera,S682.11
  9. In Vitro Rapid Propagation System of Peach Yu Dwarfing Rootstock No.1 and Optimization of Its SSR-PCR System,S662.1
  10. Identification of SRAP Molecular Markers Linked to Gynoecious Loci in Citrullus Lanatus (Thunb.) Mansfeld,S651
  11. Association Analysis for Seed Shape Traits and 100-seed Weight in Soybean (Glycine Max L. Merr.),S565.1
  12. Screening Marker Genotypes of Elite Combining Ability for Yield Traits in Parents of Hybrid Japonica Rice (Oryza Sativa L),S511.22
  13. Construction of Linkage Genetic Map and Detection of QTL for Seven Agronomic Traits Including 100-seed Weight in Soybean (Glycine Max L. Merr.),S565.1
  14. The Research of SSR for Distinctness and Uniformity Evaluation of Henan Wheat (Triticum Aestivum) Varieties,S512.1
  15. Mechanism of Fruit Cracking and Molecular Marker in Watermelon(Citrulls.lanatus),S651
  16. Screening of Markers Related to TYLCV Resistance and Research on Pyramiding Resistance in Marker-Assisted Selection in Tomato,S641.2
  17. Study on the Physiological Differentiation and Genetic Diversity of Exserohilum Turcicum in Northeastern China,S435.131
  18. Development of SSR and AFLP Markers about Panax Ginseng,S567.51
  19. The Preliminary Study of Induction of CO2 Laser Radiation on Soybean,S565.1
  20. The Molecular Identification and Preliminary Study on Mutagenic Mechanisms of Lotus Mutants Induced by Ion Implantation,S682.32

CLC: > Agricultural Sciences > Gardening > Fruit trees gardening > Pome > Pear
© 2012 www.DissertationTopic.Net  Mobile