Lv Yan-Wen, Wang Zi-Yun, He Zi-Han, Xiao Yu, Wu Chao, Hu Xin-Sheng
College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou, 510642, China.
Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, Guangzhou, 510642, China.
Sci Rep. 2025 Jun 25;15(1):20296. doi: 10.1038/s41598-025-06816-x.
Toona is of a high economic value and has a great potential for industrial and medicinal utilization. Currently, the mitochondrial genome information of this genus is incomplete. Here we sequenced the mitochondrial genomes of T. rubriflora and T. microcarpa, and re-sequenced four varieties of T. ciliata. The mitochondrial genome of T. rubriflora was 653,710 bp in length, with a typical circular structure and the GC content of 45.42%. The mitochondrial genome of T. microcarpa was successfully assembled in two circulars, designated as chromosome 1 and chromosome 2, respectively. Chromosome 1 had 474,320 bp and its GC content was 45.37%. Chromosome 2 had 166,958 bp and its GC content was 46.64%. Comparative analyses of Toona mitochondrial genomes revealed that species were highly conserved in GC content, coding gene sequences and codon usage frequency. Mononucleotide repeats were the dominant type of genome repeats. Small differences existed among species in RNA editing sites, intracellular genome homology between mitochondrial and chloroplast genomes and between mitochondrial and nuclear genomes. Most protein coding genes (PCGs) were under purifying selection. Species in Toona were relatively recently divergent, and the varieties of T. ciliata were well genetically mixed. Overall, this study provided comprehensive information on Toona mitochondrial genomes, which could be used for species identification and molecular studies on Toona.
香椿具有很高的经济价值，在工业和药用利用方面具有巨大潜力。目前，该属的线粒体基因组信息不完整。在此，我们对红椿和小果香椿的线粒体基因组进行了测序，并对四种红毛椿变种进行了重测序。红椿的线粒体基因组长度为653,710 bp，具有典型的环状结构，GC含量为45.42%。小果香椿的线粒体基因组成功组装成两个环状，分别命名为染色体1和染色体2。染色体1有474,320 bp，其GC含量为45.37%。染色体2有166,958 bp，其GC含量为46.64%。香椿线粒体基因组的比较分析表明，物种在GC含量、编码基因序列和密码子使用频率方面高度保守。单核苷酸重复是基因组重复的主要类型。物种之间在RNA编辑位点、线粒体与叶绿体基因组以及线粒体与核基因组之间的细胞内基因组同源性方面存在微小差异。大多数蛋白质编码基因（PCG）受到纯化选择。香椿属物种的分化时间相对较近，红毛椿变种的基因混合良好。总体而言，本研究提供了关于香椿线粒体基因组的全面信息，可用于香椿的物种鉴定和分子研究。
