Phylogenetic Relationships of Sugarcane Related Genera and Species Based on ITS Sequences of Nuclear Ribosomal DNA

Sugarcane related genera and species are important germplasm resources in sugarcane breeding. The internal transcribed spacer (ITS) sequence of 120 Saccharinae accessions that belong to 8 genera and 37 species were used to analyze their genetic relationships and construct phylogentic relationships with Pennisetum purpureum as an outgroup. The results showed that the sequence lengths were 200–208 bp for ITS1, 215–221 bp for ITS2, and 164 bp for 5.8sDNA with variable sites of 91, 93, and 18, respectively. The informative sites were 70, 68, and 9 for ITS1, ITS2, and 5.8sDNA, and the GC contents were 60.4%–69.1%, 66.1%–73.4%, and 54.1%–58.0%, respectively. According to the ratio of the variable sites and the ratio of informative sites to all sites, ITS sequence had richer variance than 5.8sDNA sequence, and the variance of ITS1 sequence was richer than that of ITS2 sequence. The result of genetic distance analysis revealed that that Miscanthus and Triarrhena were the closest genera to Saccharum, followed by Erianthus and Narenga, and genera Microstegium, Spodiopogon, and Imperata represented the furthest relationships with Saccharum. In the phylogenic tree constructed using neighbor-joining and maximum parsimony methods, the sugarcane related genera and species were separated into 10 groups. Erianthus arundinaceus should be classified into Erianthus genus rather than in Saccharum genus. Triarrhena is likely to be involved in Miscanthus. The 2 species from Narenga were sepearted in different groups, of which N. porphyrocoma was grouped with E. rockii, and N. allax was in an independent group. The Erianthus and Miscanthus species went to different groups, indicating the complex genetic relationships within genera.

摘 要以狼尾草属(Pennisetum Rich.)的象草(P. purpureum) 为外群体, 依据rDNA-ITS序列探讨了甘蔗亚族(Saccharinae)内与甘蔗植物分类关系较近的8属37种120份材料的系统进化关系, 结果表明, ITS1序列长度为200∼ 208 bp, 变异位点91个, 简约信息位点70个, GC含量为60.4%∼ 69.1%; ITS2序列长度为215∼ 221 bp, 变异位点93个, 简约信息位点68个, GC含量为66.1%∼ 73.4%; 5.8sDNA序列长度为164 bp, 变异位点18个, 简约信息位点9个, GC含量为54.1%∼ 58.0%; 根据变异位点, 简约信息位点占总位点的比例可以看出, ITS序列比5.8sDNA序列变异程度高, 其中ITS1序列又较ITS2序列变异丰富。属种间遗传距离表明芒属(Miscanthus)和荻属(Triarrhena)与甘蔗属(Saccharum)的亲缘关系最近, 其次为蔗茅属(Erianthus)和河八王属(Narenga); 而莠竹属(Microstegium)、大油芒属(Spodiopogon)、白茅属(Imperata)与甘蔗属亲缘关系较远。根据甘蔗近缘属种的NJ和MP系统发育关系, 支持将斑茅(E. arundinaceus)归入蔗茅属, 荻属归入芒属的观点; 河八王属的河八王(N. porphyrocoma)与滇蔗茅(E. rockii)亲缘关系较近, 而与同属的金猫尾(N. fallax)亲缘关系较远; 蔗茅属和芒属属种系统进化关系较其他属种复杂; 有4份材料被发现鉴定有误, 不应用于后续研究。