Isolation and characterization of flavanols from Anthocephalus cadamba and evaluation of their antioxidant, antigenotoxic, cytotoxic and COX-2 inhibitory activities

Population Structure and Genetic Diversity in the Natural Distribution of Neolamarckia cadamba in China

Neolamarckia cadamba (Roxb.) Bosser is a fast-growing deciduous tree species and belongs to the Neolamarckia genus of the Rubiaceae family. This species has great economic and medical values in addition to being an important timber species for multiple industrial purposes. However, few studies have examined the genetic diversity and population structure in the natural distribution of this species in China. Here, we applied both the haploid nrDNA ITS (619 bp for aligned sequences) and mtDNA (2 polymorphic loci) markers to investigate 10 natural populations (239 individuals in total) that covered most of the distribution of the species in China. The results showed that the nucleotide diversity was π = 0.1185 ± 0.0242 for the nrDNA ITS markers and π = 0.00038 ± 0.00052 for the mtDNA markers. The haplotype diversity for the mtDNA markers was h = 0.1952 ± 0.2532. The population genetic differentiation was small (Fstn = 0.0294) for the nrDNA ITS markers but large (Fstm = 0.6765) for the mtDNA markers. There were no significant effects of isolation by distance (IBD), by elevation, and by two climatic factors (annual average precipitation and tem perature). A geographic structure among populations (Nst<Gst) was absent. Phylogenetic analysis showed a highly genetic mixture among individuals of the ten populations. Pollen flow was substantially greater than seed flow (mp/ms ≫ 1.0) and played a dominant role in shaping population genetic structure. The nrDNA ITS sequences were neutral and all local populations did not undergo demographic expansion. The overall results provide fundamental information for the genetic conservation and breeding of this miraculous tree.

A complete sequence of mitochondrial genome of Neolamarckia cadamba and its use for systematic analysis

Neolamarckia cadamba is an important tropical and subtropical tree for timber industry in southern China and is also a medicinal plant because of the secondary product cadambine. N. cadamba belongs to Rubiaceae family and its taxonomic relationships with other species are not fully evaluated based on genome sequences. Here, we report the complete sequences of mitochondrial genome of N. cadamba, which is 414,980 bp in length and successfully assembled in two genome circles (109,836 bp and 305,144 bp). The mtDNA harbors 83 genes in total, including 40 protein-coding genes (PCGs), 31 transfer RNA genes, 6 ribosomal RNA genes, and 6 other genes. The base composition of the whole genome is estimated as 27.26% for base A, 22.63% for C, 22.53% for G, and 27.56% for T, with the A + T content of 54.82% (54.45% in the small circle and 54.79% in the large circle). Repetitive sequences account for ~ 0.14% of the whole genome. A maximum likelihood (ML) tree based on DNA sequences of 24 PCGs supports that N. cadamba belongs to order Gentianales. A ML tree based on rps3 gene of 60 species in family Rubiaceae shows that N. cadamba is more related to Cephalanthus accidentalis and Hymenodictyon parvifolium and belongs to the Cinchonoideae subfamily. The result indicates that N. cadamba is genetically distant from the species and genera of Rubiaceae in systematic position. As the first sequence of mitochondrial genome of N. cadamba, it will provide a useful resource to investigate genetic variation and develop molecular markers for genetic breeding in the future.