Guangxi Key Laboratory of Traditional Chinese Medicine Quality Standards, Guangxi Institute of Chinese Medicine & Pharmaceutical Science, Nanning, 530022, China.
College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin, 150000, China.
Sci Rep. 2024 Oct 9;14(1):23523. doi: 10.1038/s41598-024-75763-w.
To determine the role of internal transcribed spacer 2 (ITS2) in the identification of Spatholobus suberectus and explore the genetic diversity of S. suberectus. A total of 292 ITS2s from S. suberectus and 17 other plant species were analysed. S. suberectus was clustered separately in the phylogenetic tree. The genetic distance between species was greater than that within S. suberectus. Synonymous substitution rate (Ks) analysis revealed that ITS2 diverged the most recently within S. suberectus (Ks = 0.0022). These findings suggested that ITS2 is suitable for the identification of S. suberectus. The ITS2s were divided into 8 haplotypes and 4 evolutionary branches on the basis of secondary structure, indicating that there was variation within S. suberectus. Evolutionary analysis revealed that the GC content of paired regions (pGC) was greater than that of unpaired regions (upGC), and the pGC showed a decreasing trend, whereas the upGC remained unchanged. Single-base mutation was the main cause of base pair substitution. In both the initial state and the equilibrium state, the substitution rate of GC was higher than that of AU. The increase in the GC content was partly attributed to GC-biased gene conversion (gBGC). High GC content reflected the high recombination and mutation rates of ITS2, which is the basis for species identification and genetic diversity. We characterized the sequence and structural characteristics of S. suberectus ITS2 in detail, providing a reference and basis for the identification of S. suberectus and its products, as well as the protection and utilization of wild resources.
为了确定内转录间隔区 2（ITS2）在鸡血藤鉴定中的作用，并探讨鸡血藤的遗传多样性。对 292 个鸡血藤 ITS2 序列和 17 个其他植物物种的 ITS2 序列进行了分析。鸡血藤在系统发育树中单独聚类。种间的遗传距离大于鸡血藤内的遗传距离。同义替代率（Ks）分析表明，ITS2 在鸡血藤内最近分化（Ks=0.0022）。这些发现表明 ITS2 适合用于鸡血藤的鉴定。根据二级结构，ITS2 分为 8 种单倍型和 4 个进化枝，表明鸡血藤内存在变异。进化分析表明，配对区的 GC 含量（pGC）大于非配对区的 GC 含量（upGC），pGC 呈下降趋势，而 upGC 保持不变。单碱基突变是碱基对替换的主要原因。在初始状态和平衡状态下，GC 的替代率均高于 AU。GC 含量的增加部分归因于 GC 偏向性基因转换（gBGC）。高 GC 含量反映了 ITS2 的高重组和突变率，这是物种鉴定和遗传多样性的基础。我们详细描述了鸡血藤 ITS2 的序列和结构特征，为鸡血藤及其产品的鉴定以及野生资源的保护和利用提供了参考和依据。
