柴胡转录组SSR的分布及序列特征分析

Analysis of SSR distribution and sequence characteristics of Bupleurum chinense DC. Transcriptome

  • 摘要: 【目的】分析柴胡转录组中SSR的分布及序列特征,为开发多态性良好的、功能基因相关的SSR标记提供理论依据。【方法】以不同温度处理的柴胡种子为材料,经高通量转录组测序后,使用Trinity对测序结果进行de novo组装,并利用MISA对组装得到的Unigenes进行SSR位点搜索,最后统计分析SSR的分布及序列特征。【结果】从转录组数据组装获得244194条Unigenes,其N50值为1036 bp,平均长度791 bp,总长度193138105 bp。从Unigenes序列中共检测到50303个SSR位点,去除20405个复合型SSR位点,以29898个单一型SSR位点为后续分析对象。转录组SSR的出现频率为12.24%,平均分布距离6.46 kb,主要重复基元类型为二核苷酸,共17105个,占SSR总数的57.21%,其次为三核苷酸和单核苷酸,分别占SSR总数的20.75%和20.46%,四核苷酸~六核苷酸重复基元数量均较少。转录组SSR中,共有97种重复基元,其中二核苷酸和三核苷酸重复基元分别以AT/AT和ATC/GAT为主,分别占SSR总数的33.33%和3.98%;重复次数5~10次的SSR位点数量最多,共27942个,占SSR总数的93.46%。转录组SSR序列长度存在明显差异(12~76 bp),平均长度15.28 bp。【结论】柴胡转录组的SSR位点出现频率较高,类型较丰富,具有开发出高多态性SSR分子标记的潜力,将其用于柴胡的遗传多样性分析、种质资源评价及分子标记辅助育种等研究。

     

    Abstract: 【Objective】 The SSR locus information and sequence characteristics in the transcriptome of Bupleurum chinense DC. were analyzed,so as to provide the basis for the development of functional gene-related SSR markers with good polymorphism.【Method】The processed seeds of B. chinense were used as materials to perform high-throughput transcriptome sequencing. Trinity was used to assemble the sequencing results for De Novo assembly. The unigenes obtained were searched for the presence of SSR sites by MISA software and then the SSR data was statistically analyzed.【Result】244194 unigenes were assembled from B. chinense DC. The transcriptome data had an N50 value of 1036 bp,an average length of 791 bp and a total length of 193138105 bp. A total of 50303 SSR loci were identified from the unigene sequences,among which 20405 were complex SSR loci and 29898 SSR loci were actually analyzed. The frequency of SSR accounted for 12.24% of all unigenes with an average distribution distance of 6.46 kb. The major repeat motifs were dinucleotide(17105),accounting for 57.21% of all SSRs, followed by trinucleotide and mononucleotide(20.75% and 20.46%, respectively). The proportion of tetranucleotide repeat units to hexanucleotide repeat units was low. 97 kinds of repeat motifs were found in the B. chinense DC. transcriptome. The main repeat motif types in dinucleotide were AT/AT and in trinucleotide were ATC/GAT, which accounted for 33.33% and 3.98% of the total SSR,respectively. The types of SSR repeat units with 5 to 10 repeats had the highest proportion,with a total of 27942,accounting for 93.46% of the total SSRs. The sequence length ranged from 12 bp to 76 bp,with an average length of 15.28 bp.【Conclusion】The SSR loci in the B. chinense transcriptome have high frequency and diversity,and it is possible to develop SSR primers with high polymorphism,which can be used in the analysis of B. chinense genetic diversity,germplasm resource evaluation and molecular marker-assisted breeding.

     

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