Chromosome-level genome assembly of Indian mangrove (Ceriops tagal) revealed a genome-wide duplication event predating the divergence of Rhizophoraceae mangrove species.

Mangrove ecosystems are unique, highly diverse, provide benefits to humans, and aid in coastal protection. The Indian mangrove, or spurred mangrove, [Ceriops tagal (Perr.) C. B. Rob.] is a member of the Rhizophoraceae family and is commonly found along the intertidal zones in tropical regions in Southeast Asia, southern Asia, and Africa. Here, we present the first high-quality reference genome assembly of the Ceriops species. A preliminary draft assembly, generated from the 10× Genomics linked-read library, was scaffolded using the proximity ligation chromatin contact mapping technique (Hi-C) to obtain a chromosome-scale assembly of 231,919,005 bases with an N50 length of 11,408,429 bases. The benchmarking universal single-copy orthologs (BUSCO) analysis revealed that C. tagal gene predictions recovered 95.8% of the highly conserved orthologs. Phylogenetic analyses suggested that C. tagal diverged from the last common ancestor of flat-leaf spurred mangrove [C. decandra (Griff.) Ding Hou] and C. zippeliana Blume ∼10.4 million yr ago (MYA), and the last common ancestor of genera Ceriops, Kandelia, and Rhizophora diverged from that of genus Bruguiera ∼49.4 MYA. In addition, our analysis of the transversion rate at fourfold-degenerate sites from orthologous gene pairs provided evidence supporting a recent whole-genome duplication in C. tagal. The STRUCTURE and principal component analyses illustrated that C. tagal individuals investigated in this study were the admixture of two subpopulations, the genetic background of which was influenced primarily by location. The availability of genomic and transcriptomic resources and biodiversity data reported in this work will be useful for future studies that may shed light on adaptive evolutions of mangrove species.

De Novo Reference Assembly of the Upriver Orange Mangrove (Bruguiera sexangula) Genome.

Upriver orange mangrove (Bruguiera sexangula) is a member of the most mangrove-rich taxon (Rhizophoraceae family) and is commonly distributed in the intertidal zones in tropical and subtropical latitudes. In this study, we employed the 10× Genomics linked-read technology to obtain a preliminary de novo assembly of the B. sexangula genome, which was further scaffolded to a pseudomolecule level using the Bruguiera parviflora genome as a reference. The final assembly of the B. sexangula genome contained 260 Mb with an N50 scaffold length of 11,020,310 bases. The assembly comprised 18 pseudomolecules (corresponding to the haploid chromosome number in B. sexangula), covering 204,645,832 bases or 78.6% of the 260-Mb assembly. We predicted a total of 23,978 protein-coding sequences, 17,598 of which were associated with gene ontology terms. Our gene prediction recovered 96.6% of the highly conserved orthologs based on the Benchmarking Universal Single-Copy Orthologs (BUSCO) analysis. The chromosome-level assembly presented in this work provides a valuable genetic resource to help strengthen our understanding of mangroves' physiological and morphological adaptations to the intertidal zones.

Inhibitory effects of flavonoids from stem bark of Derris indica on the formation of advanced glycation end products.

ETHNOPHARMACOLOGICAL RELEVANCE: Derris indica (Lamk.) Bennet has been used in traditional medicine in many countries for the treatment of bronchitis, whooping cough, rheumatic joints and dipsia in diabetes. In addition, several studies have revealed that this plant displayed various pharmacological activities including anti-diabetic. The present study was designed to isolate the active compounds from its stem bark and evaluate their inhibitory activity on the formation of advanced glycation end products. MATERIAL AND METHODS: The EtOAc extract of the stem bark of Derris indica was isolated by column chromatographic techniques. The structures of isolated compounds were established on the basis of extensive spectroscopic methods. All compounds were assayed for their inhibitory effects on advanced glycation end products formation using BSA-methylglyoxal assay. RESULTS: Chromatographic fractionation of the EtOAc extract of Derris indica stem bark led to the isolation of two new pyranoflavonoids, derrisins A and B (1-2), along with 11 known flavonoids (3-13). The inhibitory activities of the compounds on the formation of advanced glycation end products were evaluated. Derrisin B (2) was the most active compound with IC50 value of 18.0µM, and displayed stronger inhibitory activity compared with positive control aminoguanidine. CONCLUSIONS: This study provided the possibility that a pyranoflavonoid (2) found in Derris indica might have therapeutic potential as an inhibitor against the formation of advanced glycation end products.