De novo Transcriptome Assembly of Senna occidentalis Sheds Light on the Anthraquinone Biosynthesis Pathway

Mechanistic insights into the protective role of Senna occidentalis extract in mitigating sodium arsenite-induced testicular toxicity

Sodium arsenite (NaAsO₂), a common environmental pollutant, negatively affects male fertility by impairing spermatogenesis, disrupting hormones, and inducing oxidative stress in testicular tissue. This study evaluated the protective effect of Senna occidentalis aqueous leaf extract (SOLAq) against NaAsO₂-induced reproductive toxicity in male Wistar rats. Twenty-five rats were randomly assigned to the five groups: Group 1 served as the control. Group 2 received NaAsO₂ (5 mg/kg) daily. Treatment groups 3 and 4 received a single daily dose of 250 mg/kg and 500 mg/kg of SOLAq  +  NaAsO₂ (5 mg/kg), respectively. Group 5 received Silymarin (50 mg/kg)  +   5 mg/kg of NaAsO₂. All treatments were administered orally for 28 days. Rat treated with only NaAsO₂ had a significant decrease (p < 0.05) in sperm concentration, motility, and viability besides a significant increase in immotile and morphologically abnormal spermatozoa and an increase in the MDA level together with a significant decrease in CAT, SOD, and GSH activity. Also, NaAsO₂ suppresses hormonal levels of FSH, LH and testosterone and affects testicular histopathological alterations. SOLAq co-treatment alleviated these effects by enhancing the antioxidant status, improving the sperm characteristics, normalizing hormonal profile, and maintaining testicular tissue structure in a dose-dependent manner.

Transcriptome sequencing on different ages of Saraca asoca bark: Insights from tannin biosynthetic pathways and EST-SSR marker design

The bark of Saraca asoca is extensively used for treating gynecological issues, primarily due to its tannin content. This study focused on transcriptome sequencing of young (BY; 0-6 years), middle-aged (BM; 6-12 years), and old (BO; >12 years) Ashoka barks. The de novo assembly produced 1,37,451 unigenes of 1,31,647,800 bp from BY, 1,16,825 unigenes of 1,15,283,571 bp from BM, and 81,825 unigenes of 68,553,092 bp from BO samples. These transcripts closely matched with Glycine max and Cajanus cajan. Transcriptome analysis identified key genes and enzymes in the tannin biosynthetic pathway, with higher levels of phenylpropanoid and flavonoid pathways observed in middle-aged samples, followed by young and old samples. Pathway enrichment analysis indicated that the Differentially Expressed Genes (DEGs) were predominantly in the biosynthetic pathways of flavonoids, isoflavonoids, anthocyanins, terpenoids, and isoquinoline alkaloids. The study also examined the up-regulated and down-regulated DEGs involved in tannin production across the different sample comparisons, revealing the flavonoid pathway to be the most regulated. Additionally, 9612, 8053, and 4659 simple sequence repeats (SSRs) were identified from BY, BM, and BO transcripts, respectively. Fourteen EST-SSR markers specific to tannins were designed and validated, with one found to be polymorphic. This research represents the first report on transcriptome sequencing and EST-SSR markers from various ages of Saraca asoca bark, providing a foundation for future genetic mapping and conservation efforts of this vulnerable species.

Identification and characterization of compounds that improve plant photosynthesis and growth under light stress conditions

To meet the escalating food and fuel demands of a growing global population and industry, food production requires a 50% increase by 2050. However, various environmental stresses, such as excessive light, significantly inhibit plant growth and lead to substantial reductions in crop yields. A major contributing factor to such declines is the reduction in photosynthetic capacity. In this study, a chemical-screening system based on standard 96-well plate and tobacco leaf tissue was developed. With this system, several anthraquinone derivatives that could alleviate high light stress from plants were identified. Application of these chemicals induced greater photosynthetic capacities and better plant growth during and after exposure to light stress for 20-96 hours in tobacco, lettuce, tomato and Arabidopsis. Mechanistic investigations unveiled that these chemicals exhibited electron-accepting abilities at PSI in vitro and improve PSI efficiency in vivo, indicating that the photoprotective effect could be a result of PSI acceptor side oxidation induced by these chemicals. Meanwhile, no adverse effects on plant growth were observed in chemical treated plants under non-stressful cultivation conditions. This study implies that anthraquinone derivatives can confer high light stress tolerance in plants, resulting in improved plant photosynthesis and growth in light stress environments.

Unveiling Anthraquinones: Diverse Health Benefits of an Essential Secondary Metabolite

Since ancient times, plants have been used as a remedy for numerous diseases. The pharmacological properties of plants are due to the presence of secondary metabolites like terpenoids, flavonoids, alkaloids, etc. Anthraquinones represent a group of naturally occurring quinones found generously across various plant species. Anthraquinones attract a significant amount of attention due to their reported efficacy in treating a wide range of diseases. Their complex chemical structures, combined with inherent medicinal properties, underscore their potential as agents for therapy. They demonstrate several therapeutic properties such as laxative, antitumor, antimalarial, antibacterial, antifungal, antioxidant, etc. Anthraquinones are found in different forms (derivatives) in plants, and they exhibit various medicinal properties due to their structure and chemical nature. The precursors for the biosynthesis of anthraquinones in higher plants are provided by different pathways such as plastidic hemiterpenoid 2-C-methyl-D-erthriol4-phosphate (MEP), mevalonate (MVA), isochorismate synthase and polyketide. Anthraquinones possess several medicinal properties and a complex biosynthetic pathway, making them good candidates for patenting new products, synthesis methods, and biotechnological production advancements. By conducting a thorough analysis of scientific literature, this review provides insights into the intricate interplay between anthraquinone biosynthesis and its broad-ranging contributions to human health.

Plant anthraquinones: Classification, distribution, biosynthesis, and regulation

Anthraquinones are polycyclic compounds with an unsaturated diketone structure (quinoid moiety). As important secondary metabolites of plants, anthraquinones play an important role in the response of many biological processes and environmental factors. Anthraquinones are common in the human diet and have a variety of biological activities including anticancer, antibacterial, and antioxidant activities that reduce disease risk. The biological activity of anthraquinones depends on the substitution pattern of their hydroxyl groups on the anthraquinone ring structure. However, there is still a lack of systematic summary on the distribution, classification, and biosynthesis of plant anthraquinones. Therefore, this paper systematically reviews the research progress of the distribution, classification, biosynthesis, and regulation of plant anthraquinones. Additionally, we discuss future opportunities in anthraquinone research, including biotechnology, therapeutic products, and dietary anthraquinones.

Comparative Physiological and Transcriptome Analyses of Tolerant and Susceptible Cultivars Reveal the Molecular Mechanism of Cold Tolerance in Anthurium andraeanum

Anthurium andraeanum is a tropical ornamental flower. The cost of Anthurium production is higher under low temperature (non-freezing) conditions; therefore, it is important to increase its cold tolerance. However, the molecular mechanisms underlying the response of Anthurium to cold stress remain elusive. In this study, comparative physiological and transcriptome sequencing analyses of two cultivars with contrasting cold tolerances were conducted to evaluate the cold stress response at the flowering stage. The activities of superoxide dismutase and peroxidase and the contents of proline, soluble sugar, and malondialdehyde increased under cold stress in the leaves of the cold tolerant cultivar Elegang (E) and cold susceptible cultivar Menghuang (MH), while the soluble protein content decreased in MH and increased in E. Using RNA sequencing, 24,695 differentially expressed genes (DEGs) were identified from comparisons between cultivars under the same conditions or between the treatment and control groups of a single cultivar, 9132 of which were common cold-responsive DEGs. Heat-shock proteins and pectinesterases were upregulated in E and downregulated in MH, indicating that these proteins are essential for Anthurium cold tolerance. Furthermore, four modules related to cold treatment were obtained by weighted gene co-expression network analysis. The expression of the top 20 hub genes in these modules was induced by cold stress in E or MH, suggesting they might be crucial contributors to cold tolerance. DEGs were significantly enriched in plant hormone signal transduction pathways, trehalose metabolism, and ribosomal proteins, suggesting these processes play important roles in Anthurium's cold stress response. This study provides a basis for elucidating the mechanism of cold tolerance in A. andraeanum and potential targets for molecular breeding.

Widely targeted metabolomic, transcriptomic, and metagenomic profiling reveal microbe-plant-metabolic reprogramming patterns mediated by Streptomyces pactum Act12 enhance the fruit quality of Capsicum annuum L

Plant growth-promoting rhizobacteria, such as Streptomyces pactum Act12, promote crop growth and stress resistance, but their contribution to fruit quality is still poorly understood. Herein we conducted a field experiment to ascertain the effects of S. pactum Act12-mediated metabolic reprogramming and underlying mechanisms in pepper (Capsicum annuum L.) fruit based on widely targeted metabolomic and transcriptomic profiling. We additionally performed metagenomic analysis to elucidate the potential relationship between S. pactum Act12-mediated reshaping of rhizosphere microbial communities and pepper fruit quality. Soil inoculation with S. pactum Act12 considerably increased the accumulation of capsaicinoids, carbohydrates, organic acids, flavonoids, anthraquinones, unsaturated fatty acids, vitamins, and phenolic acids in pepper fruit samples. Consequently, fruit flavor, taste, and color were modified, accompanied by elevated contents of nutrients and bioactive compounds. Increased microbial diversity and recruitment of potentially beneficial taxa were observed in inoculated soil samples, with crosstalk between microbial gene functions and pepper fruit metabolism. The reformed structure and function of rhizosphere microbial communities were closely associated with pepper fruit quality. Our findings indicate that S. pactum Act12-mediated interactions between rhizosphere microbial communities and pepper plants are responsible for intricate fruit metabolic reprogramming patterns, which enhance not only overall fruit quality but also consumer acceptability.

Comparative Transcriptome Analyses of Different Rheum officinale Tissues Reveal Differentially Expressed Genes Associated with Anthraquinone, Catechin, and Gallic Acid Biosynthesis

Rheum officinale Baill. is an important traditional Chinese medicinal herb, its dried roots and rhizomes being widely utilized to cure diverse diseases. However, previous studies mainly focused on the active compounds and their pharmacological effects, and the molecular mechanism underlying the biosynthesis of these ingredients in R. officinale is still elusive. Here, we performed comparative transcriptome analyses to elucidate the differentially expressed genes (DEGs) in the root, stem, and leaf of R. officinale. A total of 236,031 unigenes with N50 of 769 bp was generated, 136,329 (57.76%) of which were annotated. A total of 5884 DEGs was identified after the comparative analyses of different tissues; 175 and 126 key enzyme genes with tissue-specific expression were found in the anthraquinone, catechin/gallic acid biosynthetic pathway, respectively, and some of these key enzyme genes were verified by qRT-PCR. The phylogeny of the PKS III family in Polygonaceae indicated that probably only PL_741 PKSIII1, PL_11549 PKSIII5, and PL_101745 PKSIII6 encoded PKSIII in the polyketide pathway. These results will shed light on the molecular basis of the tissue-specific accumulation and regulation of secondary metabolites in R. officinale, and lay a foundation for the future genetic diversity, molecular assisted breeding, and germplasm resource improvement of this essential medicinal plant.