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拟南芥suf3突变体对种子萌发及胚胎发育影响的初步研究
The Influences of Arabidopsis Suf3 Mutant in Seed Germination and Embryo Development
【作者】 燕志强；
【作者基本信息】 兰州大学 ， 细胞生物学， 2009， 博士
【摘要】 高等植物中,胚胎的发育关系到种子的形成,而种子的萌发又关系到物种的延续,这两个发育过程都起到至关重要的作用。拟南芥作为一种模式植物,是研究胚胎发育和种子萌发的理想材料。我们的研究采用分析拟南芥突变体表型的方法,将拟南芥肌动蛋白相关蛋白ARP6定位到这两个发育过程中。拟南芥的胚胎发育是一个复杂的基因调控过程,到目前为止,已经发现了不下于200个基因在胚胎发育过程中起作用。胚胎极性的建立,细胞分裂,母性基因的表达以及激素途径等都会影响到胚胎的发育。种子的萌发同样是一个复杂的调控过程,除了相关基因的调控作用外,环境条件也有重要的影响。在这项研究中,我们首先得到了拟南芥的ARP6基因缺失突变体suf3,通过对suf3表型的分析,我们发现了suf3在胚胎发育和种子萌发方面都存在明显缺陷。进一步的研究表明,部分suf3在胚胎发育的早期,胚柄的发育就出现了异常,虽然胚柄是胚胎发育过程中的暂时性结构,但其作用却不能忽视。而在稍后的发育时期中,我们在suf3中观察到了退化的胚胎,很可能是由胚柄发育异常所造成的。在种子萌发方面,suf3的萌发存在延迟现象,特别是第二天和第三天,其萌发率明显低于野生型,随后的研究表明,GA能够部分恢复这种表型,而低浓度的ABA却能加剧这种表型,说明suf3的萌发延迟表型是由GA和ABA激素途径共同调控的,半定量RT-PCR实验中相关基因的表达也证实了这一点。NaCl、甘露醇等所造成的胁迫条件同样会影响到种子的萌发率,suf3对各种胁迫处理更加敏感,说明suf3在胁迫反应中存在缺陷。分子生物学实验结果也证明了这一点,suf3中胁迫诱导基因RD29A的表达量低于野生型。之前的研究已经阐明拟南芥中ARP6是染色质修饰复合体SWR1的一个组分,而SWR1的作用是促进相关染色质区域组蛋白H2A到H2A.Z的转化,从而激活该区域基因的表达。因此,我们推测suf3所造成的胚胎发育以及种子萌发方面的表型,很可能是由于在这两个发育过程中起重要作用的相关基因表达出现异常所致。而suf3突变体植株在发育的各个时期所表现出的丰富表型,也说明了ARP6是一种多效的发育调控因子,同时也说明了其作为染色质修饰复合体的成分对基因表达调控具有普遍性。
【Abstract】 In higher plants,embryo development influences the formation of seeds,and seed germination related to the continuation of the specie.Both of them play crucial roles in the development process.Arabidopsis,as a model plant,is an ideal material for studying embryo development and seed germination.Our research shows that Arabidopsis ARP6 play a part in these development processes.Arabidopsis embryo development is a high complicated gene controlled process.There are about 200 genes have been identified which are related to this process.Polarity,cell division, maternal genes and hormones all play important roles in embryo development.Seed germination is also a high complicated process that related to environment cues.In this study,we analyzed the phenotype of loss-of-function ARP6 mutant suf3,and found that it is default in embryo development and seed germination.The suspensors of some suf3 seeds are short and abnormal curvature in 8-cells period.Then we find that there are several devolutive embryos.The germination rate of suf3 seeds is delayed compared with wildtype in the second and third days.GA can partly restore this phenotype,while low concentrations of ABA can increase this phenotype.These results show that GA and ABA pathways both regulate the seed germination phenotype of suf3.NaCl and mannitol stresses also impact the seed germination rate. The suf3 seeds are more sensitive to these stresses than wildtype.Semi-quantitative RT-PCR showed that the expression of the stress-induced gene RD29A in suf3 is lower than in wild type.ARP6 have been found is a component of chromatin modification complex SWR1,which can facilitate the transformation of histone H2A to H2A.Z in order to activate the expression of related genes.Therefore,we speculate that the embryonic development and the seed germination phenotypes of suf3 may be due to abnormal expression of genes in these processes.So many phenotypes of suf3 in different developmental periods indicate that ARP6 is a pleiotropic development regulator which universally regulates the expression of many other genes.