摘要：
Sequences comparison of ribosomal internal transcribed spacer (ITS) could provide evidence for the systematic classi-fication and evolutionary relationships of main bast fiber crops and other species. In this study, the ITS sequences of 32 main bast fiber crops and 11 other species with reference genome sequences were obtained from cloning or GenBank database. The whole gene length, G+C content, and the difference of homologous percentage were analysed using MEGE software. The ITS average lengths of sequences from jute (Corchorus), kenaf (Hibiscus), ramie (Boehmeria nivea) and flax (Linum usitatissimum) were 963, 939, 658, and 686 bp, respectively. And the corresponding G+C contents were 57.87%, 58.03%, 59.05%, and 53.75%, respectively. The variation of jute (Corchorus) concentrated on a region of 220 to 386 bp, kenaf (Hibiscus) on two regions of 206 to 347 bp and 599 to 713 bp, ramie (Boehmeria nivea) on four regions of 158 to 163 bp, 193 to 199 bp, 288 to 333 bp, and 681to 688 bp, and flax (Linum usitatissimum) on five regions of 219 to 229 bp, 235 to 240 bp, 427 to 432 bp, 468 to 484 bp, and 588 to 594 bp. Phylogenetic analysis showed that jute and kenaf shared a relatively close genetic relationship while the others had a far genetic relationship, which is consistent with the relationship of traditional species classification in systematic botany. In study of com-parative genomics, the genome sequecne of cotton might be regarded as a reference for kenaf or jute, and the genome sequence of Populus trichocarpa or Ricinus communis might be regarded as a reference for ramie. We deduced that the evolutionary time of kenaf, jute, ramie and flax could be roughly estimated as 33.7, 65.3, 67.5, and 90.5 million years ago, respectively, showing the longer evolution time the more variation regions of ITS in different species of bast fiber crops in the same genus.%比较主要麻类作物和测序植物间的ITS序列,可明确它们间系统位置和进化关系.本研究采用PCR扩增和搜索GenBank数据库,获得32份麻类作物和11份测序作物的核糖体内转录间隔区(internal transcribed spacers,ITS)序列,利用MEGE软件分析ITS长度、G+C含量与同源性百分比差异.结果表明,黄麻属、红麻属、苎麻属和亚麻属的ITS基本序列全长分别为963、939、658和686 bp;G+C含量分别为57.87%、58.03%、59.05%和53.75%.黄麻属变异区域集中在220~386 bp间,红麻属变异区域集中在2个区段(206~347 bp,599~713 bp),苎麻属ITS变异区域分布在4个区段(158~163 bp、193~199 bp、288~333 bp和681~688 bp),亚麻属ITS变异区域分布在5个区段(219~229 bp、235~240 bp、427~432 bp、468~484 bp和588~594 bp).系统位置分析表明,红麻属与棉花亲缘关系最近,黄麻与棉花亲缘关系较近;亚麻与苎麻各为一小支.系统位置分析与传统的植物分类结果较一致.研究主要麻类作物比较基因组学时,红麻、黄麻可参考棉花,苎麻可参考杨树或蓖麻.推测红麻属的进化时间约为33.7百万年前(million years ago,MYA),黄麻属约为65.3MYA,苎麻属约为67.5MYA,亚麻属约为90.5MYA.主要麻类作物进化时间越久,同属不同种之间ITS变异区段越多.
