Hongzhe Li

Juss. is a small herbaceous genus within the Bignoniaceae family. It comprises 16 species, which are subdivided into five subgenera. The species are distributed mainly in the Himalaya-Hengduan Mountains, although there are exceptions, including I. sinensis, I. algae, I. semiretschenskia, and I. potaninii. Phylogenetic analyses based on trnL-F and nr ITS sequences provided support for the monophyly of the genus and its subgenera. However, the interspecific relationships among subgenera remain unresolved, and further investigation is necessary to elucidate these relationships. In this study, we sequenced and assembled 34 chloroplast genomes from 12 Incarvillea species, representing all five subgenera, and explored the phylogeny of the genus based on the cp. genome data. The results demonstrated that 34 newly assembled chloroplast genomes exhibited lengths between 159,132 and 169,244 bp, and encoded a total of 129–141 genes. These included 84–95 protein-coding genes, 37 or 38 tRNA genes, and eight rRNA genes. A comparative analysis of the chloroplast genomes revealed the structural rearrangements and the expansions/contractions of the IR regions among the Incarvillea species. A total of 12 mutation hotspot regions were identified in the cp. genomes of the genus Incarvillea, encompassing six genes (atpI, psaI, rps18, trnQ-UUG, infA and ycf1) and six intergenic spacer regions (psbT-psbf1, rps11-rpl36, infA-rps8, trnN-GUU-ycf1, ndhE-ndhG and ndhI-ndhA). The Pi values of all highly variable regions exceeded 0.06. The phylogenetic analysis corroborated the monophyly of the genus and elucidated the relationships between five subgenere, namely ((Niedzwedzkia, Incarvillea), ((Amphicome, Olgaea),Pteroscleris)). A comprehensive comparison of cp. genomic sequences revealed the diversity of the genus Incarvillea in terms of size, gene content and gene order of cp. genomes. Based on the cp. genome data, a robust phylogenetic tree of the genus Incarvillea was generated through phylogenetic analysis, with interspecific relationships well resolved. The results of this study enhance the understanding of the evolutionary history of the genus, and will facilitate further studies on the diversity and resource protection of the genus.

Background: TheSinodielsiaclade of the subfamily Apioideae (Apiacieae) was established in 2008, and it is composed of 37 species from 17 genera. Its circumscription is still poorly delimited and unstable, and interspecific relationships in the clade lack comprehensive analysis. Chloroplast (cp.) genomes provide valuable and informative data sources for evolutionary biology and have been widely used in studies on plant phylogeny. To infer the phylogenetic history of theSinodielsiaclade, we assembled complete cp. genomes of 39 species and then performed phylogenetic analysis based on these cp. genome sequence data combined with 66 published cp. genomes from 16 genera relative to the Sinodielsia clade.Results: These 39 newly assembled genomes had a typical quadripartite structure with two inverted repeat regions (IRs: 17,599–31,486 bp) separated by a large single-copy region (LSC: 82,048–94,046 bp) and a small single-copy region (SSC: 16,343–17,917 bp). The phylogenetic analysis showed that 19 species were clustered into theSinodielsiaclade, and they were divided into two subclades. Six mutation hotspot regions were detected from the whole cp. genomes among theSinodielsiaclade, namely,rbcL–accD,ycf4–cemA,petA–psbJ,ycf1–ndhF,ndhF–rpl32 andycf1, and it was found thatndhF–rpl32 andycf1 were highly variable in the 105 sampled cp. genomes.Conclusion: TheSinodielsiaclade was subdivided into two subclades relevant to geographical distributions, except for cultivated and introduced species. Six mutation hotspot regions, especiallyndhF–rpl32 andycf1, could be used as potential DNA markers in the identification and phylogenetic analyses of theSinodielsiaclade and Apioideae. Our study provided new insights into the phylogeny of theSinodielsiaclade and valuable information on cp. genome evolution in Apioideae.

Incarvillea sinensis Lam. is the type of the genus Incarvillea Juss., and it is widely distributed, relative to other members of the genus. In this paper, we sequenced, assembled and annotated the chloroplast genome of Incarvillea sinensis. The complete chloroplast genome is 162,088 bps in size, with overall GC content of 39.4%. We annotated 113 unique genes in the plastome sequence, including 79 protein coding genes, 30 tRNA genes, and four rRNA genes. The phylogenetic analysis based on chloroplast genome sequences resulted in a different resolution on the relationships among subgenera from the former.

Angelica sinensis is one of the most widely used Chinese medicinal herb. It has been cultivated for over 900 years, and the wild resource has been on the verge of extinction owing to over-exploitation. In the present study, we assembled and characterized the complete chloroplast (cp) genomes of two wild and one cultivated individuals of A. sinensis for future genetic studies. These plastome genomes varied from 142,484 to 142,529 bp in size, and overall GC contents were about 37.5%. Phylogenetic analysis and comparison on the cp genome structure reveal that the wild A. sinensis sampled should not be the wild ancestor, but the escape of the cultivated.

The genus Luculia Sweet contains about five species of small trees or shrubs and is a member of the family Rubiaceae (tribe Cinchoneae). Luculia yunnanensis is an endangered ornamental shrub endemic to southwest China. Only two natural populations of L. yunnanensis exist in the wild according to our field investigation. It can be inferred that L. yunnanensis is facing a very high risk of extinction in the wild and an urgent conservation strategy is required. By using a modified biotin-sterptavidin capture method, 24 primer sets were identified in two wild populations. Of these primers, 11 displayed polymorphisms and 13 were monomorphic. The number of alleles per locus ranged from two to four, values for observed and expected heterozygosities ranged from 0.000 to 0.833 and from 0.431 to 0.771, with averages of 0.389 and 0.614, respectively. These markers will be useful for further investigation of conservation of resources, selecting parental types in cross-breeding, evolution of this species at the molecular level and related research in Luculia species.