杜鹃花Delavayi,一种著名的观赏植物,主要在中国云南和贵州等地区发现,具有可观的园艺价值。为了阐明R.delavayi和相关杜鹃花物种内部的系统系统发育关系和细胞器基因组差异,我们进行了R.delavayi完整线粒体基因组的测序和组装。它的全长线粒体基因组是一个单一的环状分子,跨越1,009,263bp,包含53个蛋白质编码基因,包括18个转移RNA(tRNA)基因,3核糖体RNA(rRNA)基因,和32个蛋白质编码基因。在R.delavayi线粒体基因组中总共鉴定出1,182个简单序列重复(SSRs)基因座,主要由单核苷酸组成,二核苷酸,和三核苷酸重复。核苷酸多样性分析强调了杜鹃花属线粒体基因组中多样性最高的五个基因(atp6,atp9,cox2,nad1和rpl10)。对R.delavayi的线粒体基因组与其他四种杜鹃花的线粒体基因组的比较分析表明,在21个基因中进行了复杂的重排,包括rps4,nad6,rps3,atp6,cob,atp9,nad7等。线粒体系统发育树揭示了R.delavayi和R.colorum之间的密切关系,与R.×pulchrum和R.simsii形成姐妹进化枝。此外,在R.delavayi中鉴定了126个质体到线粒体的基因转移,范围从30bp到19,385bp。这些片段共构成叶绿体和线粒体基因组的47.54%和9.52%(202,169bp),分别。还观察到复杂的线粒体到线粒体的转移,843个鉴定片段,总计312,036bp(线粒体基因组的30.92%)。超过10kb的片段可以介导线粒体分子内的同源重组。值得注意的是,我们的研究强调了R.delavayi的线粒体基因组是迄今报道的杜鹃花属中最大的基因组.在杜鹃花物种的线粒体基因组中观察到的复杂重排,单独鉴定五个潜在的分子标记位点,为杜鹃花属的物种分类和亲子关系鉴定提供了有价值的见解。
Rhododendron delavayi, a notable ornamental plant primarily found in regions of China like Yunnan and Guizhou provinces, holds substantial horticultural value. To elucidate the systematic phylogenetic relationships and organelle genomic differences within R. delavayi and related
Rhododendron species, we conducted sequencing and assembly of the complete mitochondrial genome of R. delavayi. The full-length mitochondrial genome of it was a singular circular molecule spanning 1,009,263 bp, comprising 53 protein-coding genes, including 18 transfer RNA (tRNA) genes, 3 ribosomal RNA (rRNA) genes, and 32 protein-coding genes. A total of 1,182 simple sequence repeats (SSRs) loci were identified in the R. delavayi mitochondrial genome, primarily consisting of single nucleotide, dinucleotide, and trinucleotide repeats. Nucleotide diversity analysis highlighted five genes (atp6, atp9, cox2, nad1, and rpl10) with the highest diversity within the mitochondrial genomes of
Rhododendron genus. Comparative analysis of the mitochondrial genome of R. delavayi with those of four other
Rhododendron species indicated complex rearrangements in 21 genes, including rps4, nad6, rps3, atp6, cob, atp9, nad7, among others. The mitochondrial phylogenetic tree revealed a close relationship between R. delavayi and R. decorum, forming a sister clade to R. × pulchrum and R. simsii. Furthermore, 126 plastid-to-mitochondrial gene transfers in R. delavayi were identified, ranging from 30 bp to 19,385 bp. These fragments collectively constituted 47.54 % and 9.52 % of the chloroplast and mitochondrial genomes (202,169 bp), respectively. Complex mitochondrial-to-mitochondrial transfers were also observed, with 843 identified fragments totaling 312,036 bp (30.92 % of the mitochondrial genome). Segments exceeding 10 kb may mediate homologous recombination within the mitochondrial molecules. Remarkably, our study underscores that the mitochondrial genome of R. delavayi was the largest reported within the Rhododendron genus to date. The intricate rearrangements observed in the mitochondrial genomes of
Rhododendron species, alone with the identification of five potential molecular marker sites, provided valuable insights for species classification and parentage identification within the Rhododendron genus.