Elicitation of isoflavonoids in Colombian edible legume plants with jasmonates and structurally related compounds

Improved pokeweed genome assembly and early gene expression changes in response to jasmonic acid

BACKGROUND

Jasmonic acid (JA) is a phytohormone involved in regulating responses to biotic and abiotic stress. Although the JA pathway is well characterized in model plants such as Arabidopsis thaliana, less is known about many non-model plants. Phytolacca americana (pokeweed) is native to eastern North Americana and is resilient to environmental stress. The goal of this study was to produce a publicly available pokeweed genome assembly and annotations and use this resource to determine how early response to JA changes gene expression, with particular focus on genes involved in defense.

RESULTS

We assembled the pokeweed genome de novo from approximately 30 Gb of PacBio Hifi long reads and achieved an NG50 of ~ 13.2 Mb and a minimum 93.9% complete BUSCO score for gene annotations. With this reference, we investigated the early changes in pokeweed gene expression following JA treatment. Approximately 5,100 genes were differentially expressed during the 0-6 h time course with almost equal number of genes with increased and decreased transcript levels. Cluster and gene ontology analyses indicated the downregulation of genes associated with photosynthesis and upregulation of genes involved in hormone signaling and defense. We identified orthologues of key transcription factors and constructed the first JA gene response network integrated with our transcriptomic data from orthologues of Arabidopsis genes. We discovered that pokeweed did not use leaf senescence as a means of reallocating resources during stress; rather, most secondary metabolite synthesis genes were constitutively expressed, suggesting that pokeweed directs its resources for survival over the long term. In addition, pokeweed synthesizes several RNA N-glycosylases hypothesized to function in defense, each with unique expression profiles in response to JA.

CONCLUSIONS

Our investigation of the early response of pokeweed to JA illustrates patterns of gene expression involved in defence and stress tolerance. Pokeweed provides insight into the defense mechanisms of plants beyond those observed in research models and crops, and further study may yield novel approaches to improving the resilience of plants to environmental changes. Our assembled pokeweed genome is the first within the taxonomic family Phytolaccaceae to be publicly available for continued research.

Coronatine-Induced Maize Defense against Gibberella Stalk Rot by Activating Antioxidants and Phytohormone Signaling

One of the most destructive diseases, Gibberella stalk rot (GSR), caused by Fusarium graminearum, reduces maize yields significantly. An induced resistance response is a potent and cost-effective plant defense against pathogen attack. The functional counterpart of JAs, coronatine (COR), has attracted a lot of interest recently due to its ability to control plant growth and stimulate secondary metabolism. Although several studies have focused on COR as a plant immune elicitor to improve plant resistance to pathogens, the effectiveness and underlying mechanisms of the suppressive ability against COR to F. graminearum in maize have been limited. We investigated the potential physiological and molecular mechanisms of COR in modulating maize resistance to F. graminearum. COR treatment strongly enhanced disease resistance and promoted stomatal closure with H2O2 accumulation, and 10 μg/mL was confirmed as the best concentration. COR treatment increased defense-related enzyme activity and decreased the malondialdehyde content with enhanced antioxidant enzyme activity. To identify candidate resistance genes and gain insight into the molecular mechanism of GSR resistance associated with COR, we integrated transcriptomic and metabolomic data to systemically explore the defense mechanisms of COR, and multiple hub genes were pinpointed using weighted gene correlation network analysis (WGCNA). We discovered 6 significant modules containing 10 candidate genes: WRKY transcription factor (LOC100279570), calcium-binding protein (LOC100382070), NBR1-like protein (LOC100275089), amino acid permease (LOC100382244), glutathione S-transferase (LOC541830), HXXXD-type acyl-transferase (LOC100191608), prolin-rich extensin-like receptor protein kinase (LOC100501564), AP2-like ethylene-responsive transcription factor (LOC100384380), basic leucine zipper (LOC100275351), and glycosyltransferase (LOC606486), which are highly correlated with the jasmonic acid-ethylene signaling pathway and antioxidants. In addition, a core set of metabolites, including alpha-linolenic acid metabolism and flavonoids biosynthesis linked to the hub genes, were identified. Taken together, our research revealed differentially expressed key genes and metabolites, as well as co-expression networks, associated with COR treatment of maize stems after F. graminearum infection. In addition, COR-treated maize had higher JA (JA-Ile and Me-JA) levels. We postulated that COR plays a positive role in maize resistance to F. graminearum by regulating antioxidant levels and the JA signaling pathway, and the flavonoid biosynthesis pathway is also involved in the resistance response against GSR.

Quality-controlled LC-ESI-MS food metabolomics of fenugreek (Trigonella foenum-graecum) sprouts: Insights into changes in primary and specialized metabolites

Fenugreek (Trigonella foenum-graecum L.) is an important food and spice with bioactive compounds against diabetes. In this study, fenugreek seeds germinating in darkness for 72 h were studied using quantification of trigonelline and 4-hydroxyisoleucine and an LC-ESI-MS/MS-based metabolomic approach capable of accurately estimating 237 features from various primary and specialized compound classes. During germination, the concentrations of trigonelline and 4-hydroxyisoleucine rose by 33.5% and 33.3%, respectively. At the same time, untargeted metabolomics revealed 9 putative flavonoids increasing 1.19- to 2.77-fold compared to the dormant seeds. A set of 19 steroid saponins rose by 1.08- to 31.86-fold. Primary metabolites however showed much more variability: abundance changes in amino acid derivatives, peptides and saccharides fell in the 0.09- to 22.25-fold, 0.93- to 478.79-fold and 0.36- to 941.58-fold ranges, respectively. To increase biosynthesis of specialized metabolites during germination, sprouts were exposed to 1-100 mM methyl jasmonate (MeJA) and methyl salicylate (MeSA). The hormone treatments affected normal metabolism: 67.1-83.1 % and 64.1-83.5 % of compounds showed a reduction compared to the controls in 100 mM MeJA and MeSA treatments at different sampling time points. Contrary to expectations, the abundance of flavonoids decreased, compared to the control sprouts (0.75- and 0.68-fold change medians, respectively). The same was observed for most, but not all steroid saponins. The quality-controlled untargeted metabolomics approach proved to yield excellent insight into the metabolic changes during germination of fenugreek. The results suggest that although fenugreek germination causes major shifts in plant metabolism, there are no major qualitative changes in bioactive specialized metabolites during the first three days. This stability likely translates into good bioactivity that is similar to that of the seeds. Because the large changes in the primary metabolites likely alter the nutritive value of the seed, further studies are warranted.

A Comprehensive Review of the Pharmacological Importance of Dietary Flavonoids as Hepatoprotective Agents

The liver is a crucial organ that is involved in various kinds of metabolic activity and a very stable accessory gland for the digestive system. Long-term or persistent inflammation and oxidative stress due to any reasons have a substantial impact on the beginning and continuation of chronic diseases such as hepatocellular carcinoma, liver cirrhosis, liver fibrosis, and other hepatic conditions. There are many sources which can help the liver to be healthy and enhance its metabolic potential of the liver. Since the diet is rich origin of bioactive along with antioxidant chemicals including flavonoids and polyphenols, it can control different stages of inflammation and hepatic diseases. Numerous food sources, notably vegetables, nuts, fruits, cereals, beverages, and herbal medicinal plants, are rich in bioactive chemicals called flavonoids and their derivatives like Flavones, Anthocyanins, Iso-flavonoid, Flavanones, Flavanols, and Flavan-3-ols. Most recently occurred research on flavonoids has demonstrated that they can regulate hepatoprotective properties. This is because they are essential parts of pharmaceutical and nutraceutical products due to their hepatoprotective, antioxidative, and immune-modulating characteristics. However, the characteristics of their hepatoprotective impact remain unclear. The purpose of this comprehensive review is to survey the flavonoid structure and enriched sources for their hepatoprotective and antioxidant effects concerning liver toxicity or injury.

Jasmonates in plant growth and development and elicitation of secondary metabolites: An updated overview

Secondary metabolites are incontestably key specialized molecules with proven health-promoting effects on human beings. Naturally synthesized secondary metabolites are considered an important source of pharmaceuticals, food additives, cosmetics, flavors, etc., Therefore, enhancing the biosynthesis of these relevant metabolites by maintaining natural authenticity is getting more attention. The application of exogenous jasmonates (JAs) is well recognized for its ability to trigger plant growth and development. JAs have a large spectrum of action that covers seed germination, hypocotyl growth regulation, root elongation, petal expansion, and apical hook growth. This hormone is considered as one of the key regulators of the plant's growth and development when the plant is under biotic or abiotic stress. The JAs regulate signal transduction through cross-talking with other genes in plants and thereby deploy an appropriate metabolism in the normal or stressed conditions. It has also been found to be an effective chemical elicitor for the synthesis of naturally occurring secondary metabolites. This review discusses the significance of JAs in the growth and development of plants and the successful outcomes of jasmonate-driven elicitation of secondary metabolites including flavonoids, anthraquinones, anthocyanin, xanthonoid, and more from various plant species. However, as the enhancement of these metabolites is essentially measured via in vitro cell culture or foliar spray, the large-scale production is significantly limited. Recent advancements in the plant cell culture technology lay the possibilities for the large-scale manufacturing of plant-derived secondary metabolites. With the insights about the genetic background of the metabolite biosynthetic pathway, synthetic biology also appears to be a potential avenue for accelerating their production. This review, therefore, also discussed the potential manoeuvres that can be deployed to synthesis plant secondary metabolites at the large-scale using plant cell, tissue, and organ cultures.