Comparative Analysis of Proanthocyanidin Metabolism and Genes Regulatory Network in Fresh Leaves of Two Different Ecotypes of Tetrastigma hemsleyanum

A chromosome-level genome assembly for Onobrychis viciifolia reveals gene copy number gain underlying enhanced proanthocyanidin biosynthesis

Sainfoin (Onobrychis viciifolia), which belongs to subfamily Papilionoideae of Leguminosae, is a vital perennial forage known as "holy hay" due to its high contents of crude proteins and proanthocyanidins (PAs, also called condensed tannins) that have various pharmacological properties in animal feed, such as alleviating rumen tympanic disease in ruminants. In this study, we select an autotetraploid common sainfoin (2n = 4x = 28) and report its high-quality chromosome-level genome assembly with 28 pseudochromosomes and four haplotypes (~1950.14 Mb, contig N50 = 10.91 Mb). The copy numbers of genes involved in PA biosynthesis in sainfoin are significantly greater than those in four selected Fabales species, namely, autotetraploid Medicago sativa and three other diploid species, Lotus japonicus, Medicago truncatula, and Glycine max. Furthermore, gene expansion is confirmed to be the key contributor to the increased expression of these genes and subsequent PA enhancement in sainfoin. Transcriptomic analyses reveal that the expression of genes involved in the PA biosynthesis pathway is significantly increased in the lines with high PA content compared to the lines with medium and low PA content. The sainfoin genome assembly will improve our understanding of leguminous genome evolution and biosynthesis of secondary metabolites in sainfoin.

Insights into Metabolic Engineering of Bioactive Molecules in Tetrastigma hemsleyanum Diels & Gilg: A Traditional Medicinal Herb

Plants are a vital source of bioactive molecules for various drug development processes. Tetrastigma hemsleyanum is one of the endangered medicinal plant species well known to the world due to its wide range of therapeutic effects. Many bioactive molecules have been identified from this plant, including many classes of secondary metabolites such as flavonoids, phenols, terpenoids, steroids, alkaloids, etc. Due to its slow growth, it usually takes 3-5 years to meet commercial medicinal materials for this plant. Also, T. hemsleyanum contains low amounts of specific bioactive compounds, which are challenging to isolate easily. Currently, scientists are attempting to increase bioactive molecules' production from medicinal plants in different ways or to synthesize them chemically. The genomic tools helped to understand medicinal plants' genome organization and led to manipulating genes responsible for various biosynthesis pathways. Metabolic engineering has made it possible to enhance the production of secondary metabolites by introducing manipulated biosynthetic pathways to attain high levels of desirable bioactive molecules. Metabolic engineering is a promising approach for improving the production of secondary metabolites over a short time period. In this review, we have highlighted the scope of various biotechnological approaches for metabolic engineering to enhance the production of secondary metabolites for pharmaceutical applications in T. hemsleyanum. Also, we summarized the progress made in metabolic engineering for bioactive molecule enhancement in T. hemsleyanum. It may lead to reducing the destruction of the natural habitat of T. hemsleyanum and conserving them through the cost-effective production of bioactive molecules in the future.

Morphological, Molecular, and Biochemical Characterization of a Unique Lentil (Lens culinaris Medik.) Genotype Showing Seed-Coat Color Anomalies Due to Altered Anthocyanin Pathway

This study reports the identification of a unique lentil (Lens culinaris Medik.) genotype L4717-NM, a natural mutant (NM) derived from a variety L4717, producing brown, black, and spotted seed-coat colored seeds in a single plant, generation after generation, in different frequencies. The genetic similarity of L4717 with that of L4717-NM expressing anomalous seed-coat color was established using 54 SSR markers. In addition, various biochemical parameters such as TPC (total phenolic content), TFC (total flavonoid content), DPPH (2,2-diphenyl-1-picrylhydrazyl), FRAP (ferric reducing antioxidant power), H2O2 (peroxide quantification), TCC (total carotenoids content), TAC (total anthocyanin content), and TAA (total ascorbic acid) were also studied in the seeds, sprouts, and seedlings of L4717, brown, black, and spotted seed-coat colored seeds. Stage-specific variations for the key biochemical parameters were recorded, and seedling stage was found the best for many parameters. Moreover, seeds with black seed coat showed better nutraceutical values for most of the studied traits. A highly significant (p ≤ 0.01) and positive correlation was observed between DPPH and TPC, TAA, TFC, etc., whereas, protein content showed a negative correlation with the other studied parameters. The seed coat is maternal tissue and we expect expression of seed-coat color as per the maternal genotype. However, such an anomalous seed-coat expression, which seems to probably be governed by some transposable element in the identified genotype, warrants more detailed studies involving exploitation of the anthocyanin pathway.