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林业科学 ›› 2011, Vol. 47 ›› Issue (3): 52-58.doi: 10.11707/j.1001-7488.20110309

• 论文 • 上一篇    下一篇

毛白杨蔗糖合酶基因PtSUS1的克隆、表达及单核苷酸多态性分析

潘炜, 田佳星, 杜庆章, 张志毅, 张德强   

  1. 北京林业大学 林木育种国家工程实验室 林木花卉遗传育种教育部重点实验室 北京 100083
  • 收稿日期:2010-11-23 修回日期:2011-01-14 出版日期:2011-03-25 发布日期:2011-03-25
  • 通讯作者: 张德强

Isolation, Expression and Single Nucleotide Polymorphisms Analysis of Sucrose Synthase Gene (PtSUS 1 ) from Populus tomentosa

Pan Wei, Tian Jiaxing, Du Qingzhang, Zhang Zhiyi, Zhang Deqiang   

  1. National Engineering Laboratory for Tree Breeding Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education Beijing Forestry University Beijing 100083
  • Received:2010-11-23 Revised:2011-01-14 Online:2011-03-25 Published:2011-03-25

摘要:

利用RT-PCR方法,首次从毛白杨成熟木质部cDNA文库中分离出PtSUS 1 cDNA全长,并进行了测序和序列分析。结果表明: 克隆的毛白杨PtSUS 1 cDNA片段总长为2 703 bp,基因内部含有完整的开放阅读框架,大小为2 415 bp,可编码长度为805个氨基酸残基的蛋白质,所推导的蛋白质氨基酸序列与拟南芥AtSUS 1 、水稻OsSUS 1 的蛋白质氨基酸序列同源性分别为83.4%,75.7%。组织特异性Realtime-PCR结果显示, PtSUS 1 在成熟木质部表达丰度最高,在成熟叶片、根部和正在发育的木质部表达丰度中等,在韧皮部和形成层有少量表达,在嫩叶与顶端分生组织中表达丰度最低。在此基础上,组合利用MEGA4.0和DnaSP4.50.4软件对毛白杨40株基因型个体的PtSUS 1 序列进行比对和分析,共检测到235个单核苷酸多态性(SNP)位点,SNP频率为1/25 bp,多样性指数π为0.009 24。在外显子区域,共检测到66个SNP位点,其中55个为同义突变,10个为错义突变,1个为无义突变。在编码区内,非同义突变与同义突变的比率<1,这一结果显示在毛白杨物种演化过程中,纯化选择是PtSUS 1 基因内同义SNP位点主要的进化驱动力。

关键词: 毛白杨, 纤维素, 蔗糖合酶, 系统进化, 单核苷酸多态性

Abstract:

In this study, a full-length cDNA encoding PtSUS 1 was isolated from the cDNA library prepared from mature xylem zone of Populus tomentosa by the RT-PCR method. The cDNA is 2 703 bp in length with an open reading frame (ORF) which encodes a protein of 805 aa. The deduced protein sequence of the PtSUS 1 shares 83.4%, and 75.7% identity with Arabidopsis thaliana AtSUS 1 , and Oryza sativa OsSUS 1 , respectively. Tissue differential expression detected with Realtime-PCR indicated that the PtSUS 1 transcripts were the most abundant mRNA products in mature xylem, medium in mature leaf, root, and developing xylem, scarcer in the phloem and cambium, and the scarcest detected in young leaf and apical shoot meristems. The genomic sequences of PtSUS 1 in 40 individuals were aligned, compared and analyzed using the software of MEGA4.0 and DnaSP4.50.7. A total of 235 single nucleotide polymorphisms (SNPs) were detected and the frequency and diversity of SNPs were 1/25 bp and 0.009 24, respectively. There were 66 SNPs detected in the coding regions of PtSUS 1 , of which 55, 10 and 1 are silent, missense, and nonsense mutations, respectively. In coding region of PtSUS 1 , the nonsynonymous nucleotide substitutions (πnonsyn) was markedly lower than πsyn, with the πnonsyn/πsyn ratio < 1, suggesting that diversity at the synonymous sites of exon regions resulted from strong purifying selection.

Key words: Populus tomentosa, cellulose, sucrose synthase, phylogeny, single nucleotide polymorphisms

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