油茶基因组微卫星特征分析

对油茶基因组约10%覆盖度的DNA序列进行微卫星查找,共获得11 344个重复单元长度为1～6碱基的微卫星。在此基础上,通过对这些微卫星序列分析发现:在油茶基因组中长度为二核苷酸的微卫星重复单元最为丰富,占27.1%;在单碱基重复和二碱基重复这两种类型中,最主要的优势重复单元分别是A/T以及AT/TA、AG/TC。三碱基、四碱基、五碱基重复类型中,(AAN)n、(AAAN)n和(AAAAN)n为对应的优势重复单元,这些优势重复单元中富含碱基A和T。油茶基因组中变异程度高的微卫星(长度≥20 bp)约占11.7%。分析还发现,除单核苷酸重复微卫星外,油茶基因组微卫星长度的变异速率与重复单元长度呈负相关,即油茶基因组中长度较短的微卫星变异速率较快,而较长的重复单元变异速度较慢,相对较为稳定。

Characteristic analysis of microsatellites of Camellia spp.

There were 11 344 microsatellites(SSRs) ranged from 1 to 6 bp detected by analyzing the DNA sequences covering about 10 % of genome Camellia.Among these SSRs,dinucleotide repeats were most abundant(27.1 %).For the composition of microsatellites,A/T repeats were the most frequent motifs in mononucleotide repeats,and AT/TA,AG/TC repeats were the most in dinucleotide repeats,while(AAN)n,(AAAN)n and(AAAAN)n repeats were dominant in tri-,tetra-and pentanucleotide repeats,respectively.All the dominant repeat motifs for different type of SSRs were abundant in nucleotides A and T.In Camellia genome,microsatellites longer than 20bp accounted for about 11.7 % of the detected SSRs.Repeats,repeat motif lengths were found negatively correlated with the variation rate except mononucleotide repeats,thus,the shorter repeats would have faster substitution rate.