林奈杜鹃花,1753年,北半球最大的木本植物属,包括园艺中一些最重要的物种。杜鹃花,1911年,TrifloraSleumer1947小节的成员,举例说明了典型的高山杜鹃花物种。对杜鹃花完整叶绿体基因组的分析为杜鹃花物种的进化提供了新的见解,并增强了系统发育关系的分辨率。这个基因组由207,478个碱基对组成,包括一对47,249bp的反向重复序列(IRs),由110,367bp的大型单拷贝(LSC)区域和2,613bp的小型单拷贝(SSC)区域分开。它包含110个基因:77个蛋白质编码基因,29个tRNA,四个独特的rRNA(4.5S,5S,16S,和23S),在IRs中有16个基因重复。比较分析揭示了杜鹃花叶绿体基因组结构的大量多样性,识别第四个变异模式。具体来说,四个高度分歧的区域(trnI-rpoB,ndhE-psaC,rpl32-ndhF,rrn16S-trnI)在基因间间隔区。此外,鉴定了76个简单序列重复。在四个基因(cemA,rps4、rpl16和rpl14),高Ka/Ks比率证明。基于两个数据集(共享的蛋白质编码基因和完整的叶绿体基因组)的系统发育重建表明,R.ambiguum与R.concinnumHemsley密切相关,1889.然而,TrifloraPojarkova小节的系统发育位置,1952年物种仍未解决,这表明在杜鹃花中使用完整的叶绿体基因组进行系统发育研究需要仔细考虑。总的来说,我们的发现提供了有价值的遗传信息,将增强对进化的理解,分子生物学,和杜鹃花的遗传改良。
Rhododendron Linnaeus, 1753, the largest genus of woody plants in the Northern Hemisphere, includes some of the most significant species in horticulture. Rhododendronambiguum Hemsl, 1911, a member of subsection Triflora Sleumer 1947, exemplifies typical alpine Rhododendron species. The analysis of the complete chloroplast genome of R.ambiguum offers new insights into the evolution of Rhododendron species and enhances the resolution of phylogenetic relationships. This genome is composed of 207,478 base pairs, including a pair of inverted repeats (IRs) of 47,249 bp each, separated by a large single-copy (LSC) region of 110,367 bp and a small single-copy (SSC) region of 2,613 bp. It contains 110 genes: 77 protein-coding genes, 29 tRNAs, four unique rRNAs (4.5S, 5S, 16S, and 23S), with 16 genes duplicated in the IRs. Comparative analyses reveal substantial diversity in the Rhododendron chloroplast genome structures, identifying a fourth variant pattern. Specifically, four highly divergent regions (trnI-rpoB, ndhE-psaC, rpl32-ndhF, rrn16S-trnI) were noted in the intergenic spacers. Additionally, 76 simple sequence repeats were identified. Positive selection signals were detected in four genes (cemA, rps4, rpl16, and rpl14), evidenced by high Ka/Ks ratios. Phylogenetic reconstruction based on two datasets (shared protein-coding genes and complete chloroplast genomes) suggests that R.ambiguum is closely related to R.concinnum Hemsley, 1889. However, the phylogenetic positions of subsection Triflora Pojarkova, 1952 species remain unresolved, indicating that the use of complete chloroplast genomes for phylogenetic research in Rhododendron requires careful consideration. Overall, our findings provide valuable genetic information that will enhance understanding of the evolution, molecular biology, and genetic improvement of Rhododendron spieces.