远缘杂交诱导的油菜遗传与表观遗传变化

摘要

不同物种的基因组融合导致的异源多倍化过程常常伴随着遗传学和表观遗传学的改变。如将一个亲本的基因组从异源多倍体中分离出来，可较准确的研究异源多倍化所诱导的基因组变化。在本研究中，首先利用甘蓝型油菜（Brassica napus，2n=38，AACC）与诸葛菜（Orychophragmus violaceus，2n=24，OO）的体细胞融合产生的异源六倍体(2n=62，AACCOO)与甘蓝型油菜(2n=38，AACC)连续回交所培育出的9个不同附加系，自交所产生的甘蓝型油菜类型后代为材料，通过AFLP、SSAP、MSAP分析，与甘蓝型油菜供体比较，研究结果表明经历多倍化后甘蓝型油菜在基因组成分、转座子活性、DNA甲基化方面都发生了一定程度的;由不同附加系衍生出来的甘蓝型油菜之间的差异很有可能是由于受到了不同的外源染色体的影响。值得指出，那些包含有诸葛菜rRNA显性位点（相对于甘蓝型油菜为显性）的附加系倾向于产生更小的变异，暗示外源rRNA的表达量对基因组的稳定有一定影响。这些结果对理解不同基因组的融合与分离过程中亲本染色体组的遗传改变提供了新的线索。
　　其次，天然甘蓝型油菜经历了长期的进化过程，确切的亲本难以确定，故很难研究祖先基因组的改变。我们利用AFLP、SSAP、MSAP等技术，观察了从甘蓝型油菜中分离出的白菜型油菜（Brassica rapa，2n=20，AA）的基因组组成、转座子活动、DNA甲基化。通过与甘蓝型油菜供体比较，由于C染色体组的丢失，分离出的白菜型油菜显示大量的AFLP片段丢失，但也有大量的新带产生，可能重复杂交所诱导和外源片段渗入。11个A基因组特异的LTR（Copia）反转录转座子表现高频率的SSAP片段丢失和低频率的新带产生。还检测到广泛的甲基化变化。这些结果暗示分离出的白菜型油菜中发生较大范围的遗传学和表观遗传学改变，这些变化可能来源于长期的进化、杂交诱导、外源染色体片段的渗入和其它因素。

目录

声明

摘要

ABSTRACT

List of Acronyms

1．Literature review

1．1 Polyploidization

1．2 Distribution of Polyploids

1．3 Allopolyploidization

1．4 Comparison between natural and synhetic allopolyploids

1．5 Comparison between hybridization and whole genome duplication

1．6 Advantages of polyploids

1．7 Disadvantages of polyploids

1．8 Genetic changes in polyploids

1．9 Gene expression changes in Polyploids

1．10 Transposon activation in polyploids

1．11 Epigenetic perturbation in polyploids

1．11．1 DNA methylation and histone modification

1．11．2 Nucleolar dominance in hybrids

1．12 No clear distinction between some genetic and epigenetic changes

1．13 Differential intensity of genetic and epigenetie changes in the same polyploids

1．14 Aneuploidy

1．14．1 Generation of aneuploids

1．14．2 Aneuploidy in animals

1．14．3 Aneuploidy in plants

1．14．4 Impact of aneuploidy on gene expression

1．14．5 Detrimental effects of aneuploidy on cell physiology

1．14．6 Beneficial effects of aneuploidy

1．15 Brassica crop species as a model system for studyingpoly ploidization

2．Genetic and epigenetic changes in oilseed rape(Brassica napus L．)extracted from intergeneric allopolyploid and additions with Orychophragmus

2．1 Materials and methods

2．1．1 Plant materials

2．1．2 Methodology

2．2 Results

2．2．1 Phenotype and fertility of B．napus plants extracted from alien additions

2．2．2 AFLP analysis of genomic changes in the extracted B．napus plants

2．2．3 SSAP analysis of transposon variations in the extracted B．napus plants

2．2．4 DNA methylation alteration in novel B．napus

2．3 Discussion

3．Genetic and epigenetic changes in the restituted Brassica rapa ancestor from allotetraploid B．napus

3．1 Materials and methods

3．1．1 Plant materials

3．1．2 Methodology

3．2 Results

3．2．1 AFLP analysis of genomic changes in the extracted B．rapa

3．2．2 Retrotransposon alterations revealed by SSAP in the extracted B．rapa

3．2．3 Extensive DNA methylation changes in B．rapa-type line

3．3 Discussion

Literature cited

4．Summary

4．1 New Findings

4．2 Future Perspective

Acknowledgements

Supplementary Materials

Author Introduction