【摘要】 叶绿体基因组的结构和组成较为保守且其序列片段的变异速率适中,适合用于研究植物的系统进化。以我国主要栽培桑种广东桑(Morus atropurpurea)的品种一串红为实验材料,利用Illumina高通量测序平台进行广东桑叶绿体全基因组测序,分析基因组结构,并且与已报道近缘物种的叶绿体基因组进行比较。广东桑叶绿体基因组长159 113 bp,2个反向重复区(IRa和IRb)长度均为25 707 bp,被大单拷贝区(LSC)和小单拷贝区(SSC)分隔开,LSC和SSC大小分别为87 824 bp、19 875bp;叶绿体基因组共有130个基因,包含85个蛋白质的编码基因、37个t RNA基因和8个r RNA基因,其中含有内含子的基因数量是24个,有22个基因只含有1个内含子,2个基因(ycf3和clp P)含有2个内含子。广东桑叶绿体基因组的基因数目、种类以及CG含量与其它桑属植物的叶绿体基因组类似。通过生物信息学分析在广东桑叶绿体基因组得到83个简单重复序列(SSR)位点,单核苷酸、二核苷酸、三核苷酸、四核苷酸和五核苷酸重复基序的数量分别是60、8、3、10、2个,未发现六核苷酸重复序列,大多数位点都偏向A或T组成。用MEGA 6.0软件通过最大似然法和邻近法基于叶绿体全基因组序列对包括4个桑种在内的14个物种进行聚类分析,其中广东桑和蒙桑(Morus mongolica)聚在一起,印度桑(Morus indica)和川桑(Morus notabilis)聚在一起。研究结果对于叶绿体基因组工程研究以及桑属种间的分子标记开发和优良品种培育具有一定参考价值。更多还原

【Abstract】 The structure and composition of chloroplast genome are conservative and the variation rate of its fragments is moderate,which are suitable for studying the systematic evolution of plants. A cultivated species of M orus atropurpurea named Yichuanhong was used as experimental material and Illumina high-throughput sequencing technology was employed to sequence its chloroplast genome which was analyzed and compared with the reported chloroplast genomes of genetically close species. The chloroplast genome of M.atropurpurea is 159 113 bp in size. It contains two inverted repeats( IRa and IRb) of 25 707 bp each,which are separated by a large single-copy( LSC) region of 87 824 bp and a small single-copy( SSC) region of 19 875 bp. The chloroplast genome contains130 genes,including 85 protein coding genes,37 t RNA genes and 8 r RNA genes. 24 genes contain introns,among which 22 genes have only one intron and 2 genes( ycf3 and clp P) have two introns. The number,type and CG content of M. atropurpurea chloroplast genes are similar with other Morus plants. 83 simple sequence repeats( SSR) loci were found in M. atropurpurea chloroplast genome through bioinformatics analysis. The number of mono-,di-,tri-,tetra- and pentanucleotide repeat motifs is 60,8,3,10 and 2 respectively. No hexa-nucleotide repeat was found.Most SSR loci have an A- or T-skewed base composition. Meanwhile,MEGA 6. 0 software was employed to construct the maximum-likelihood and neighbor-joining phylogenetic trees using chloroplast genomes of 4 Morus species and 10 other plant species. It was found that M. atropurpurea and Morus mongolica forms one clade,and Morus indica and Morus notabilis forms another clade. These data provide good references for conducting plant chloroplast genome projects,developing mulberry inter-species molecular markers,and breeding excellent mulberry varieties.更多还原