四种栎属青冈亚属植物叶绿体基因组特征及系统发育研究

栎属青冈亚属植物的系统发育地位长期存在着争议，部分种的种间关系不明确。为揭示宁冈青冈(Quercus ningangensis)、曼青冈(Q.oxyodon)、毛曼青冈(Q.gambleana)、竹叶青冈(Q.neglecta)的叶绿体基因组特征及系统发育关系，该研究选择以上4种栎属青冈亚属植物的成熟叶片进行二代测序，对其叶绿体基因组结构和特征进行分析，并结合相关类群进行系统发育研究。结果表明：(1)宁冈青冈、曼青冈、毛曼青冈、竹叶青冈的叶绿体基因组序列长度分别为160 906、160 883、160 832、160 784 bp,均编码133个基因，包括88个蛋白质编码基因、37个tRNA基因、8个rRNA基因。(2)4种栎属青冈亚属植物偏好以A/T结尾的密码子，质体基因组变异区域主要存在于非编码序列。(3)通过IR边界分析得出，4种栎属青冈亚属植物存在ycf1假基因且在IRb/SSC区域发生扩张。(4)系统发育分析显示，在壳斗科中，水青冈属(Fagus)和轮叶三棱栎属(Trigonobalanus)较早分化出来，栎亚属(subg.Quercus)未形成一个单系群，叶绿体基因组建树结...

Comparison of chloroplast genomes and phylogenic analysis of four species of Quercus subg. Cyclobalanopsis

The phylogenetic status of Quercus subg. Cyclobalanopsis has long been controversial and the interspecific relationships of some species are unclear. At present, chloroplast genomes have been used to solve the phylogenetic problems of subg. Quercus and Castanea in the Fagaceae, but there are few researches on solving the phylogenetic problems of Quercus subg. Cyclobalanopsis with chloroplast genome information. To reveal the chloroplasts genome characteristics and phylogenetic relationships of Quercus ningangensis, Q. oxyodon, Q. gambleana and Q. neglecta. In this study, mature leaves of the above four species of Quercus subg. Cyclobalanopsis were selected for next-generation sequencing, and the chloroplast genome structure and characteristics were analyzed, phylogeny was studied in combination with related taxa. The results were as follows:(1)The chloroplast genome sequences of Q. ningangensis, Q. oxyodon, Q. gambleana and Q. neglecta were 160 906, 160 883, 160 832, 160 784 bp, respectively. They all encoded 133 genes, including 88 protein-coding genes, 37 tRNA genes and 8 rRNA genes.(2)The codons ending in A/T were preferred by the four species of Quercus subg. Cyclobalanopsis, and the variation regions of plastid genome mainly existed in non-coding sequences.(3)According to IR boundary analysis, ycf1 pseudogene was found in four species of Quercus subg. Cyclobalanopsis and expanded in IRb/SSC regions.(4)Phylogenetic analysis showed that Fagus and Trigonobalanus were differentiated early in Fagaceae, while subg. Quercus did not form a monophyly. The results of phylogenetic tree based on chloroplast genome were consistent with the nuclear marker plasmid markers. Interspersed between Ilex group and Cerris group in subg. Quercus. (5)The Flora of China and some local flora treated Q. gambleana as a separate species, while ZHOU Zhekun and DENG Min et al. treated Q. gambleana as a subspecies according to the characteristics of leaves. The phylogenetic status of Q. gambleana is still controversial. Based on the chloroplast genome information and previous morphological analysis results, the present study supported the idea that Q. gambleana existed as an independent species. This study provides basic data for discussing the phylogenetic status of the Quercus subg. Cyclobalanopsis, the division of its groups, and the resolution of doubtful relationships among them.