拟南芥EFD基因影响花粉壁模式形成的机理研究

发布时间：2018-03-08 00:17

  本文选题：拟南芥　切入点：EFD　出处：《上海师范大学》2017年硕士论文　论文类型：学位论文

【摘要】：花粉的形成对被子植物的生殖繁衍至关重要,而花粉壁各层结构的正常发育对于产生成熟而有活力的花粉起到关键作用。花粉壁的结构组成由外到内分为外壁和花粉内壁,花粉外壁又可分为外壁外层和外壁内层。花粉壁的结构因物种不同而差异很大。此花粉壁的特殊结构称之为花粉壁模式。影响花粉壁模式建成的主要因素有:胼胝质形成、初生外壁沉积、质膜波浪状形成、孢粉素沉积(花粉外壁外层的原料)等因素。目前已经发现很多影响这些过程的重要因子缺失会影响花粉壁模式建成,进而影响花粉育性。例如:影响胼胝质形成的Cal S5;影响花粉初生外壁形成的基因有NPU、RPG1、DEX1、NEF1等;影响孢粉素合成的基因CYP703A2、MS2、LAP5、LAP6等;以及影响花粉外壁内层形成的基因TEK、AGP6、AGP11、AGP23、AGP40等。但这些因素之间的关系以及调控花粉壁模式建成的分子机理仍然很不清楚。最新报道的拟南芥EFD基因编码一个核定位DNA甲基转移酶。该基因的缺失导致雄性不育,并对拟南芥花药发育过程中胼胝质的形成、初生外壁的形成以及外壁内层的形成等方面都有很大影响。此外,efd背景下大量重要基因的表达明显下调。本论文中,我们以efd突变体为切入点,将对应每个受到影响的生物学过程中的关键基因回补入efd突变体后,发现外壁内层表型未恢复,初生外壁回补植株表型恢复不显著,而外壁外层回补植株表型恢复。因此孢粉素合成过程的异常对efd花粉壁发育的影响最为关键。另外针对DNA甲基转移酶的转录沉默功能以及efd背景下与花药发育相关的基因呈现明显下调趋势,猜想EFD下游存在一个转录抑制因子负调控下游花粉壁发育的相关基因。我们将efd突变体背景下芯片数据中一个表达量上调显著的转录因子HBF在野生型野生型中过表达之后,HBF过表达植株在24℃时并未有明显表型,但在26℃时HBF过表达植株出现了一定程度的育性下降。hbf突变体背景下花药发育相关基因出现一定程度上调,而且efd hbf双突植株恢复了育性,由此初步推测该HBF转录因子是EFD下游与花药发育相关的很重要的一个转录因子。
[Abstract]:Pollen formation is very important for reproduction and reproduction of angiosperms, and the normal development of pollen wall layers plays a key role in producing mature and active pollen. The structure of pollen wall is divided into outer wall and inner wall from outside to inside. The structure of pollen wall is very different from species to species. The special structure of pollen wall is called pollen wall pattern. The main factors influencing the formation of pollen wall model are: callose formation. Factors such as primary outer wall deposition, plasma membrane wavy formation, sporopollen deposition (the raw material for the outer layer of pollen wall) and other factors have been found to affect the formation of pollen wall model. For example: Cal S5, which affects the formation of corpus callosum, the genes that influence the formation of pollen primary outer wall, the gene CYP703A2, the gene CYP703A2, the gene CYP703A2, the gene CYP703A2, the gene CYP703A2, LAP5, LAP6, and so on. The relationship between these factors and the molecular mechanism of regulating pollen wall pattern formation is still unclear. The newly reported Arabidopsis EFD gene encodes a nucleated DNA. Methyltransferase. The deletion of the gene leads to male sterility. The formation of corpus callosum, the formation of primary outer wall and the formation of inner wall of outer wall of Arabidopsis thaliana have great influence on the anther development of Arabidopsis thaliana. In addition, the expression of a large number of important genes in Arabidopsis thaliana is down-regulated. Using the efd mutants as the entry point, we added the key genes corresponding to each affected biological process into the efd mutants. We found that the phenotype of the inner layer of the outer wall did not recover, and the phenotype of the primary outer wall repair plant was not significant. Therefore, the abnormal process of sporopollen synthesis has the most important effect on the development of pollen wall of efd. In addition, the transcriptional silencing function of DNA methyltransferase and the anther development phase under efd background are the most important. The related genes showed a down-regulation trend. We conjectured the existence of a transcription suppressor gene associated with the negative regulation of downstream pollen wall development in the downstream of EFD. We have up-regulated the expression of a significant transcription factor HBF in wild-type wild type in the microarray data of efd mutants. After expression, there was no obvious phenotype of HBF overexpressed plants at 24 鈩，

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