目的 解析散斑竹根七Disporopsis aspersa、竹根七D. fuscopicta、长叶竹根七D. longifolia、深裂竹根七D. pernyi 4种竹根七属药用植物的叶绿体基因组特征与系统发育关系，筛选属内潜在物种鉴别位点，为该属植物的物种鉴定、种质资源保护、药材质量控制及开发利用提供分子基础与理论支撑。方法 以4种竹根七属药用植物的幼嫩叶片为材料进行高通量测序，完成叶绿体基因组的组装与注释，并运用生物信息学方法开展重复序列、IR区边界、密码子使用偏好、核苷酸多态性、选择压力及系统发育分析。结果 4种竹根七属药用植物的叶绿体基因组均呈典型的四分体环状结构，基因组全长为155 975～156 109 bp，总GC含量均为37.68%；均注释得到131个基因，包括85个蛋白编码基因、38个tRNA基因和8个rRNA基因。4个叶绿体基因组中的简单重复序列（simple sequence repeats，SSR）均以单核苷酸重复类型为主，长重复序列（long-sequence repeats，LSR）均以回文重复为主。4种植物的IR区边界整体较为保守，密码子使用模式基本一致，偏好使用以A或T结尾的密码子。核苷酸多态性分析表明，rrn23S和trnT-UGU在基因区域中具有较高的核苷酸多态性值（nucleotide diversity，P_i）值，rrn4.5S-rrn5S、ccsA-ndhD、rps11-rpl36和rps15-ycf1为变异程度较高的基因间区。选择压力分析显示，大多数蛋白编码基因的K_a/K_s值小于1，主要受到净化选择约束；ycf1、ycf4、psaI和cemA在部分物种组合中的K_a/K_s值大于1，可能存在与适应性进化相关的信号。系统发育分析显示，4种竹根七属植物聚集于同一分支，且节点支持率较高，并与黄精属构成姊妹群。结论 4种竹根七属植物叶绿体基因组结构与基因组成总体保守，但局部区域存在一定序列变异。筛选获得的候选高变区域可为竹根七属植物的物种鉴定和分子标记开发提供参考，系统发育结果为该属植物的分类及亲缘关系研究提供了叶绿体基因组证据。

Objective To characterize the chloroplast genomes and phylogenetic relationships of four medicinal species of Disporopsis, namely Disporopsis aspersa, D. fuscopicta, D. longifolia, and D. pernyi, and to identify potential regions for species discrimination, thereby providing a molecular and theoretical basis for species identification, germplasm resource conservation, quality control of medicinal materials, and resource development and utilization of this genus. Methods Young leaves of the four medicinal Disporopsis species were subjected to high-throughput sequencing. The chloroplast genomes were assembled and annotated, followed by bioinformatic analyses of repeat sequences, inverted repeat (IR) boundaries, codon usage bias, nucleotide diversity, selection pressure, and phylogenetic relationships. Results The chloroplast genomes of the four medicinal Disporopsis species exhibited a typical quadripartite circular structure, with genome sizes ranging from 155 975 to 156 109 bp and an overall GC content of 37.68%. A total of 131 genes were annotated in each genome, including 85 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. Simple sequence repeats (SSRs) were dominated by mononucleotide repeats, whereas long sequence repeats (LSRs) were dominated by palindromic repeats. The IR boundaries were generally conserved among the four species. Their codon usage patterns were highly similar, with a preference for codons ending in A or T. Nucleotide diversity analysis showed that rrn23S and trnT-UGU had relatively high Pi values among the genic regions, whereas rrn4.5S–rrn5S, ccsA–ndhD, rps11–rpl36, and rps15–ycf1 were highly variable intergenic regions. Selection pressure analysis showed that most protein-coding genes had Ka/Ks values below 1 and were predominantly constrained by purifying selection. However, ycf1, ycf4, psaI, and cemA had Ka/Ks values above 1 in some species comparisons, suggesting possible signals associated with adaptive evolution. Phylogenetic analysis showed that the four Disporopsis species clustered within the same well-supported branch and formed a sister group with Polygonatum. Conclusion The chloroplast genomes of the four Disporopsis species are generally conserved in genome structure and gene composition, although local sequence variation is present. The candidate highly variable regions identified in this study may provide useful references for species identification and molecular marker development in Disporopsis. The phylogenetic results also provide chloroplast genomic evidence for investigating the classification and relationships of this genus.

R282.12

2023年福建省本科高校教育教学研究项目（FBJY20230030）