桉树SWEET基因家族的分析

发布时间：2018-08-26 13:41

【摘要】：SWEET家族基因是一个新的糖转运蛋白,主要包含两个MtN3/saliva跨膜结构域,而少数原核生物只含有1个结构域。真核生物的Mt N3/saliva蛋白家族主要包括7个跨膜螺旋,但是已报道的17个拟南芥SWEET家族成员中有16个基因含有7个跨膜螺旋,有一个基因含有6个跨膜螺旋(AT1G66770)。原核生物的3个跨膜的MtN3/saliva结构域发生了复制,导致产生了真核生物的2个MtN3/saliva结构域的SWEET蛋白,由于这种特殊的结构,通常将原核生物这一基因家族称为Semi SWEETs。目前对该家族的功能研究较少,近年的研究结果表明SWEET家族基因可能作为糖转运蛋白或通过与离子转运蛋白的相互作用促进离子转运,调节包括转运糖类、发育、环境适应性在内的不同的生理过程。本研究以桉树SWEET家族基因为研究对象,对其进行了全面的分析,利用生物信息学的方法,对它们的进化、性质、结构等做了分析。主要研究结果如下:1从phytozome数据库中检索桉树、拟南芥中的所有含MtN3/Saliva结构域的基因,其中,桉树中共检索到52条同源序列,拟南芥中检索到17条同源序列。拟南芥所有17条序列均含有两个Mt N3/saliva结构域,且跨膜区大于或等于6个,全部定义为SWEET家族。而桉树52条同源序列中:有40条序列跨膜区大于或等于6个,除EgSWEET9c含有3个MtN3/saliva结构域外,其余基因均含有两个MtN3/saliva结构域,将这40个基因定义为SWEET家族成员;6条序列有两个MtN3/saliva结构域,但跨膜区少于6个,可能是SWEET家族成员;6条序列只有1个MtN3/saliva结构域,与原核生物的Semi SWEETs结构相似。2为了研究不同植物中含有MtN3/saliva结构域基因的进化和亲缘关系,本文分析了来自37个不同物种的947个含有MtN3/saliva基因。这947个基因分为11个分枝和一些OG分枝,这些基因分为A1、A2、A3和B1四个亚家族。A1亚家族主要是第三分枝,包括AtSWEET4-8和6个桉树基因,A2亚家族主要是第五分枝,主要包括AtSWEET16、AtSWEET17以及6个桉树基因,A3亚家族主要是1、2、4三个分枝,包括AtSWEET1-3和13个桉树基因,B1亚家族主要是6-11分枝,包括AtSWEET9-15以及24个桉树基因,还有2个基因不在上述亚家族内,属于OG分枝。3通过检索phytozome数据库和DNAMAN软件对桉树中的SWEET家族基因的基本性质作了分析:跨膜区大于或等于6个的40个基因序列中,两个Mt N3/saliva家族结构域所含的氨基酸个数大约都在90个左右,这40个基因的开放阅读框架(ORF)从1208bp到7084bp不等。在跨膜区少于6个的12个基因里,EgSWEET2d长度最短,EgSWEET17e长度最长。开放阅读框架从529bp到4615bp不等,外显子数目从3到6不等。4在由phytozome数据库提供的染色体位置信息的基础上将检索到的含有MtN3/saliva结构域的52个SWEET家族基因定在桉树染色体上。桉树一共有11条染色体,但检索到的这52个SWEET家族基因只有45个基因定位在染色体上,且绝大多数是成簇出现的,其余7个基因可能没有定位在拼接后的染色体上,定位在染色体上的45个基因主要分布在8条染色体上。5表达水平分析表明:34个基因在茎尖处表达量较高,37个基因在幼叶表达量较高,36个基因在老叶处表达量较高,31个基因在木质部表达量最高,在韧皮部表达量较高的基因有40个。6不同胁迫下的诱导处理表明:在葡萄糖溶液的处理下,有11个基因表达量上调,有2个基因表达量下调,有7个基因表达量基本不变;在蔗糖溶液的处理下,有15个基因表达量上调,有2个基因表达量下调,有3个基因表达量基本不变;在NaCl溶液的处理下,有11个基因表达量上调,2个基因表达量下调,7个基因表达量基本不变。由此可知,在这20个基因中,受蔗糖诱导的基因最多。这些结果为深入了解桉树SWEET家族基因提供了参考依据。
[Abstract]:The SWEET family of genes is a new sugar transporter, which mainly contains two MtN3/saliva transmembrane domains, while a few prokaryotes contain only one. The MtN3/saliva family of eukaryotes mainly consists of seven transmembrane helices, but 16 of the 17 reported members of the SWEET family in Arabidopsis contain seven transmembrane helices. A gene contains six transmembrane helixes (AT1G66770). Three transmembrane MtN3/saliva domains in prokaryotes are replicated, resulting in the production of two MtN3/saliva domain SWEET proteins in eukaryotes. Because of this special structure, the prokaryote family of genes is often referred to as Semi SWEETs. Less, recent studies have shown that SWEET family genes may act as sugar transporters or interact with ion transporters to promote ion transport and regulate different physiological processes including transporting carbohydrates, development and environmental adaptability. The main results are as follows: 1. All the genes of Eucalyptus and Arabidopsis containing MtN3/Saliva domain were retrieved from the phytozome database. Among them, 52 homologous sequences were found in Eucalyptus, and one Eucalyptus homologous sequence was found in Arabidopsis. Seventeen sequences contained two MtN3/saliva domains, and the transmembrane region was greater than or equal to six, all of which were defined as SWEET family. Of the 52 Eucalyptus homologous sequences, 40 sequences had more than or equal to six transmembrane domains. Except EgSWEET9c had three MtN3/saliva domains, the rest of the genes contained two MtN3/saliva domains. Six sequences have two MtN3/saliva domains, but less than six transmembrane domains, which may be members of the SWEET family. Six sequences have only one MtN3/saliva domain, which is similar to the structure of Simi SWEETs in prokaryotes. 947 genes from 37 different species contained MtN3/saliva gene. The 947 genes were divided into 11 branches and some OG branches. These genes were divided into four subfamilies A1, A2, A3 and B1. The A1 subfamily was mainly the third branch, including AtSWEET4-8 and six Eucalyptus genes. The A2 subfamily was mainly the fifth branch, including AtSWEET16, AtSWEET1 and six eucalyptus. Tree genes, A3 subfamily is mainly 1,2,4 three branches, including AtSWEET 1-3 and 13 Eucalyptus genes, B1 subfamily is mainly 6-11 branches, including AtSWEET 9-15 and 24 Eucalyptus genes, there are two genes not in the above subfamily, belong to OG branching. Among the 40 gene sequences with transmembrane region greater than or equal to 6, the number of amino acids in the two Mt N3/saliva family domains was about 90, and the open reading frame (ORF) of these 40 genes ranged from 1208 BP to 7084 bp. The open reading frame ranged from 529 BP to 4615 bp, and the number of exons ranged from 3 to 6. 4 On the basis of chromosome location information provided by phytozome database, 52 SWEET family genes containing MtN3/saliva domain were located on Eucalyptus chromosomes. There were 11 chromosomes in eucalyptus, but these 52 SWEET families were retrieved. Only 45 genes were located on chromosomes, and most of them appeared in clusters. The other 7 genes may not be located on spliced chromosomes. The 45 genes located on chromosomes were mainly distributed on 8 chromosomes. 5 expression level analysis showed that 34 genes were highly expressed at the tip of stem and 37 genes were on the surface of young leaves. The expression of 36 genes was higher in the old leaves, 31 genes were the highest in xylem, and 40.6 genes were induced in phloem. The results showed that 11 genes were up-regulated, 2 genes were down-regulated and 7 genes were basically unchanged under glucose treatment. Under the treatment of NaCl solution, 11 genes were up-regulated, 2 genes were down-regulated, and 3 genes were basically unchanged. Under the treatment of NaCl solution, 11 genes were up-regulated, 2 genes were down-regulated and 7 genes were basically unchanged. These results provide a reference for understanding the SWEET family genes of Eucalyptus.
【学位授予单位】：华南农业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：S792.39;Q943.2

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