Zhejiang Provincial Key Laboratory of Plant Evolutionary Ecology and Conservation, School of Life Sciences, Taizhou University, Taizhou, 318000, China.
School of Life Sciences, Shanghai Normal University, Shanghai, 200234, China.
BMC Genomics. 2023 Jun 8;24(1):310. doi: 10.1186/s12864-023-09427-w.
Cuscuta, a parasitic plant species in the Convolvulaceae family, grows in many countries and regions. However, the relationship between some species is still unclear. Therefore, more studies are needed to assess the variation of the chloroplast (cp) genome in Cuscuta species and their relationship with subgenera or sections, thus, providing important information on the evolution of Cuscuta species.
In the present study, we identified the whole cp genomes of C. epithymum, C. europaea, C. gronovii, C. chinensis and C. japonica, and then constructed a phylogenetic tree of 23 Cuscuta species based on the complete genome sequences and protein-coding genes. The complete cp genome sequences of C. epithymum and C. europaea were 96,292 and 97,661 bp long, respectively, and lacked an inverted repeat region. Most cp genomes of Cuscuta spp. have tetragonal and circular structures except for C. epithymum, C. europaea, C. pedicellata and C. approximata. Based on the number of genes and the structure of cp genome and the patterns of gene reduction, we found that C. epithymum and C. europaea belonged to subgenus Cuscuta. Most of the cp genomes of the 23 Cuscuta species had single nucleotide repeats of A and T. The inverted repeat region boundaries among species were similar in the same subgenera. Several cp genes were lost. In addition, the numbers and types of the lost genes in the same subgenus were similar. Most of the lost genes were related to photosynthesis (ndh, rpo, psa, psb, pet, and rbcL), which could have gradually caused the plants to lose the ability to photosynthesize.
Our results enrich the data on cp. genomes of genus Cuscuta. This study provides new insights into understanding the phylogenetic relationships and variations in the cp genome of Cuscuta species.
旋花科菟丝子属植物是一种寄生植物，分布于许多国家和地区。然而，一些物种之间的关系仍不清楚。因此，需要更多的研究来评估菟丝子属植物的叶绿体（cp）基因组的变异及其与亚属或节的关系，从而为菟丝子属植物的进化提供重要信息。
本研究鉴定了菟丝子属的 4 种植物，即菟丝子、欧洲菟丝子、大菟丝子、中国菟丝子和日本菟丝子的完整 cp 基因组，并基于完整基因组序列和蛋白编码基因构建了 23 种菟丝子属植物的系统发育树。菟丝子和欧洲菟丝子的完整 cp 基因组分别长 96292bp 和 97661bp，均缺乏反向重复区。除菟丝子、欧洲菟丝子、金灯藤和美洲菟丝子外，大多数菟丝子属植物的 cp 基因组均具有四方形和圆形结构。根据基因数量、cp 基因组结构和基因缺失模式，我们发现菟丝子和欧洲菟丝子属于亚属菟丝子。23 种菟丝子属植物的 cp 基因组中大多数均含有 A 和 T 的单核苷酸重复。同一亚属中物种的反向重复区边界相似。一些 cp 基因丢失。此外，同一亚属中丢失基因的数量和类型相似。大多数丢失的基因与光合作用（ndh、rpo、psa、psb、pet 和 rbcL）有关，这可能导致植物逐渐失去光合作用能力。
我们的研究结果丰富了菟丝子属 cp 基因组的数据。本研究为了解菟丝子属植物 cp 基因组的系统发育关系和变异提供了新的见解。
