基因組的演化在很大程度上受到轉(zhuǎn)座子（transposable element,TE）活動(dòng)的影響。轉(zhuǎn)座子的活躍事件不可避免的會(huì)產(chǎn)生有害突變,進(jìn)而影響基因組的穩(wěn)定性。生物體為了應(yīng)對(duì)轉(zhuǎn)座子的變化,建立了一系列的調(diào)控機(jī)制,如DNA甲基化,能夠特異性的在沉默轉(zhuǎn)座子的活性種子植物的基因組在大小差異巨大,裸子植物基因組普遍偏大,而買麻藤類植物作為裸子植物中的分支,因表型分化差異與其他種子植物相比與眾不同,基因組大小也并非裸子植物的典型代表因此,我們以買麻藤類植物,特別是百歲蘭為研究對(duì)象,試圖分析早期種子植物基因組進(jìn)化模式。。此前,裸子植物基因組被認(rèn)為均與松科植物挪威云杉基因組（20Gb）類似:具有超大的DNA含量,基因組由于缺乏有效的轉(zhuǎn)座子消除機(jī)而緩慢積累。然而買麻藤基因組測(cè)序結(jié)果表明其基因組較�。�4.1 Gb）,TE刪除率較高（非完整LTR/完整LTR=2.07:1）。為了進(jìn)一步比較基因組大小演化和甲基化調(diào)控之間的關(guān)系,以更好地理解買麻藤類植物分支和種子植物祖先,我們擴(kuò)大了樣本量,又研究了另一種買麻藤類植物——百歲蘭,一種單科單屬單種的多年生沙漠植物。百歲蘭基因組顯示出了獨(dú)有的特征:7Gb基因組包... 

【文章頁(yè)數(shù)】：58 頁(yè)

【學(xué)位級(jí)別】：碩士

【文章目錄】：
摘要
abstract
Chapter1 Introduction
    1.1 Background
    1.2 Problem statement
    1.3 Purpose of study
    1.4 Objectives of the study
Chapter2 Review of literature
    2.1 Seed plants
    2.2 Genome evolution,Transposon recombination and epigenetic silencing
    2.3 Small RNA
    2.4 DNA methylation
    2.5 Establishment of methylation
        2.5.1 Canonical pathway
        2.5.2 Non-canonical pathway
    2.6 Maintenance of methylation
    2.7 Gene body methylation(GbM)and Non-CG methylation
    2.8 DNA demethylation
    2.9 RNA directed DNA methylation functions in seed plants
        2.9.1 Developmental functions
        2.9.2 Response to Biotic and Abiotic stress
Chapter3 Research design and methodology
    3.1 Sampling procedure
    3.2 Instrumentation and procedures
    3.3 Data analysis
        3.3.1 Repeat content
        3.3.2 Solo to intact LTR ratio
        3.3.3 Methylome sequencing
        3.3.4 RdDM genes
        3.3.5 Statistical tests and graphical data representation
Chapter4 Results
    4.1 Genome size and TE content
    4.2 Methylation
        4.2.1 Context of methylation
        4.2.2 Occurrence of Rd DM genes
        4.2.3 Levels of Gene expression
        4.2.4 Occurrence of Rd DM genes in gymnosperms
    4.3 Small RNA
Chapter5 Discussion
    5.1 Genome size and repeat content
    5.2 Correlation between repeat content and methylation
    5.3 Small interfering RNA
    5.4 Functionality of methylation
Conclusion
References
Appendix
Acknowledgements
Student profile
    Authors Resume
    Publications



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