Magnesium and manganese interactively modulate parthenolide accumulation and the antioxidant defense system in the leaves of Tanacetum parthenium

The role of Manganese in tree defenses against pests and pathogens

Manganese (Mn) deficiency is a widespread occurrence across different landscapes, including agricultural systems and managed forests, and causes interruptions in the normal metabolic functioning of plants. The microelement is well-characterized for its role in the oxygen-evolving complex in photosystem II and maintenance of photosynthetic structures. Mn is also required for a variety of enzymatic reactions in secondary metabolism, which play a crucial role in defense strategies for trees. Despite the strong relationship between Mn availability and the biosynthesis of defense-related compounds, there are few studies addressing how Mn deficiency can impact tree defense mechanisms and the ensuing ecological patterns and processes. Understanding this relationship and highlighting the potentially deleterious effects of Mn deficiency in trees can also inform silvicultural and management decisions to build more robust forests. In this review, we address this relationship, focusing on forest trees. We describe Mn availability in forest soils, characterize the known impacts of Mn deficiency in plant susceptibility, and discuss the relationship between Mn and defense-related compounds by secondary metabolite class. In our review, we find several lines of evidence that low Mn availability is linked with lowered or altered secondary metabolite activity. Additionally, we compile documented instances where Mn limitation has altered the defense capabilities of the host plant and propose potential ecological repercussions when studies are not available. Ultimately, this review aims to highlight the importance of untangling the effects of Mn limitation on the ecophysiology of plants, with a focus on forest trees in both managed and natural stands.

The Malus domestica metal tolerance protein MdMTP11.1 was involved in the detoxification of excess manganese in Arabidopsis thaliana

Ion homeostasis is maintained in plant cells by specialized transporters. However, functional studies on Mn transporters in apple trees have not been reported. MdMTP11.1, which encodes a putative Mn-MTP transporter in Malus domestica, was expressed highly in leaves and induced by Mn stress. Subcellular localization analysis of the MdMTP11.1-GFP fusion protein indicated that MdMTP11.1 was targeted to the Golgi. Meanwhile, overexpression of MdMTP11.1 in Arabidopsis thaliana conferred increased resistance to plants under toxic Mn levels, as evidenced by increased biomass of whole plant and length of primary root. Analysis of Mn bioaccumulation indicated that overexpression of MdMTP11.1 effectively reduced the content of Mn in every subcellular component and chemical forms when the plants were subjected with Mn stress. The majority of Mn of action were bound to cell wall and combined with un-dissolved phosphate. Besides, contents of malondialdehyde (MDA), proline and hydrogen peroxide (H2O2) were significantly lower, while content of chlorophyll and activities of CAT, SOD, POD and APX were significantly higher in MdMTP11.1-over-expressing plants compared with that in wild type plants under Mn stress. Taken together, these results suggest that MdMTP11.1 is a Mn specific transporter localized to the Golgi can maintain the phenotype, reduce the Mn accumulation and alleviate damage of oxidative stress, conferring the positive role of Mn tolerance.

Parthenolide Augments the Chemosensitivity of Non-small-Cell Lung Cancer to Cisplatin via the PI3K/AKT Signaling Pathway

The mortality rate of non-small-cell lung cancer (NSCLC) remains high worldwide. Although cisplatin-based chemotherapy may greatly enhance patient prognosis, chemotherapy resistance remains an obstacle to curing patients with NSCLC. Therefore, overcoming drug resistance is the main route to successful treatment, and combinatorial strategies may have considerable clinical value in this effort. In this study, we observed that both parthenolide (PTL) and cisplatin (DDP) inhibited the growth of NSCLC cells in a dose- and time-dependent manner. The combination of PTL and DDP presented a synergistic inhibitory effect on NSCLC at a ratio of 50:1. The combination of PTL and DDP synergistically inhibited cell migration and invasion, inhibited cell cycle progression, and induced apoptosis of A549 and PC9 cells. Bioinformatics and network pharmacology analysis indicated that PTL may primarily affect the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway. After treatment with PTL and DDP either alone or in combination, Western blot analysis revealed that the proteins levels of Bax and cleaved Caspase-3 were upregulated, while p-PI3K, p-Akt, Caspase-3, and Bcl-2 proteins were downregulated. Among these alterations, the combination of PTL and DDP was found to exhibit the most significant effects. PTL might therefore be considered as a new option for combination therapy of NSCLC.

Assessing the variation in manganese use efficiency traits in Scottish barley landrace Bere (Hordeum vulgare L.)

BACKGROUND AND AIMS

Manganese (Mn) deficiency in barley is a global problem. It is difficult to detect in the early stages of symptom development and is commonly pre-emptively corrected by Mn foliar sprays that can be costly. Landraces adapted to marginal lands around the world represent a genetic resource for potential sustainability traits including mineral use efficiency. This research aims to confirm novel Mn use efficiency traits from the Scottish landrace Bere and use an association mapping approach to identify genetic loci associated with the trait.

METHODS

A hydroponic system was developed to identify and characterize the Mn deficiency tolerance traits in a collection of landraces, including a large number of Scottish Bere barleys, a group of six-rowed heritage landraces grown in the highlands and islands of Scotland. Measuring chlorophyll fluorescence, the effect of Mn deficiency was identified in the early stages of development. Genotypic data, generated using the 50k Illumina iSelect genotyping array, were coupled with the Mn phenotypic data to create a genome-wide association study (GWAS) identifying candidate loci associated with Mn use efficiency.

KEY RESULTS

The Bere lines generally had good Mn use efficiency traits. Individual Bere lines showed large efficiencies, with some Bere lines recording almost double chlorophyll fluorescence readings in limited Mn conditions compared with the elite cultivar Scholar. The Mn-efficient Bere lines had increased accumulation of Mn in their shoot biomass compared with elite cultivars, which was highly correlated to the chlorophyll fluorescence. Several candidate genes were identified as being associated with Mn use efficiency in the GWAS.

CONCLUSIONS

Several genomic regions for Mn use efficiency traits originating from the Bere lines were identified. Further examination and validation of these regions should be undertaken to identify candidate genes for future breeding for marginal lands.

Exploring Plant Sesquiterpene Diversity by Generating Chemical Networks

Plants produce a diverse portfolio of sesquiterpenes that are important in their response to herbivores and the interaction with other plants. Their biosynthesis from farnesyl diphosphate depends on the sesquiterpene synthases that admit different cyclizations and rearrangements to yield a blend of sesquiterpenes. Here, we investigate to what extent sesquiterpene biosynthesis metabolic pathways can be reconstructed just from the knowledge of the final product and the reaction mechanisms catalyzed by sesquiterpene synthases. We use the software package MedØlDatschgerl (MØD) to generate chemical networks and to elucidate pathways contained in them. As examples, we successfully consider the reachability of the important plant sesquiterpenes β -caryophyllene, α -humulene, and β -farnesene. We also introduce a graph database to integrate the simulation results with experimental biological evidence for the selected predicted sesquiterpenes biosynthesis.

Manganese-induced changes in glandular trichomes density and essential oils production of Mentha aquatica L. at different growth stages

Production and accumulation of essential oils in plants are influenced by intrinsic and environmental factors. Here, we attempted to elucidate the effect of manganese (Mn) supply on the density of glandular trichomes and the production of essential oils in Mentha aquatica (water mint; syn. Mentha hirsuta Huds.) at the different growth stages. To this aim, plants were treated with 100 μM of Mn (supplied as MnSO₄·H₂O) at early and late vegetative stages of growth. Then, the control and treated plants were harvested, and biochemical, morphological and molecular analyses indicated that Mn supply has affected M. aquatica at the different growth stages. The biomass, Mn accumulation, glandular trichomes density, essential oils yield and expression levels of the genes encoding enzymes involved in terpenoid biosynthesis pathway (1-Deoxy d-xylulose-5-phosphate synthase (Dxs), geranyl diphosphate synthase (Gpps), isopentenyl diphosphate isomerase (Ippi), β-caryophyllene synthase (Cps), limonene synthase (Ls) and menthofuran synthase (Mfs)) were increased by Mn supply at both growth stages. However, the increased rates of the assayed parameters were varied between the early and late vegetative stages. Moreover, the content and chemical composition of terpenoid components were affected by Mn supply and plant growth stage. There were positive and weak correlations among the study variables under the Mn supply at the different growth stages. Given these findings, we propose that the application of Mn supply at both early and late vegetative stages elevates the growth, density of glandular trichomes and production of essential oils in M. aquatica.

Changes in primary and secondary metabolites of Mentha aquatica L. exposed to different concentrations of manganese

This experiment was conducted in order to determine the effects of different concentrations of manganese (Mn) on the levels and correlations of multiple primary and secondary metabolites in Mentha aquatica. With this aim, four levels of Mn concentrations were used as follows: basic Hoagland's solution (control), 40, 80, and 160 μM of Mn supplied as MnSO₄.H₂O. The results indicated that the biomass and the contents of photosynthetic pigments and soluble carbohydrates were higher in the plants that were treated with the moderate concentrations of Mn (40 and 80 μM) than the control and 160 μM-treated plants. On the other hand, the contents of flavonoids, anthocyanins, malonaldehyde (MDA), hydrogen peroxide (H₂O₂), and the activities of antioxidant enzymes (total superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX)) were progressively increased with the enhancement of Mn concentration in the nutrient solution. In addition, there were clear differences in the content and chemical composition of essential oils among the control and treatment groups. In this study, 1,8-cineole, menthofuran, and β-caryophyllene were the most abundant constituents of essential oils in both the control and Mn-treated plants. The correlation analysis between pairs of the primary and secondary metabolites showed that there were positive and negative correlations among the variables when the Mn concentration was increased in the nutrient solution. These findings clearly display a positive effect of Mn up to 80 μM in the nutrient solution on the growth of M. aquatica.

Manganese modulates the physiological and biochemical responses of Mentha aquatica L. to ultraviolet radiation

Ultraviolet (UV) radiation as an environmental factor alters the physiological and metabolic processes in plants. Manganese (Mn) is an essential element that is required for plant growth and development. This experiment was conducted in order to determine the effects of Mn supply and UV radiation on the physiological and metabolic responses in Mentha aquatica. With this aim, three levels of Mn and UV treatments were used as follows: basic Hoagland's nutrient solution without UV radiation (control), Mn supply (100μM), UV radiation (2h daily), and UV+100μM Mn. After three weeks of treatments, the root and shoot dry weights and the contents of photosynthetic pigments were decreased under UV radiation condition. However, the contents of flavonoids, soluble carbohydrate, anthocyanins, malonaldehyde (MDA), hydrogen peroxide (H₂O₂), and the activity of antioxidant enzymes (superoxide dismutase, catalase, and peroxidase) were increased. Interestingly, Mn at 100μM concentration decreased the harmful effects of UV radiation on M. aquatica. In addition, the clear differences were observed in the terpene constituents of M. aquatica after the Mn and UV treatments. In this study, 1, 8-cineole, menthofuran and β-caryophyllene were the most abundant constituents of essential oils in both the control and treated plants. The correlation analysis between pairs of the primary and secondary metabolites showed that there were positive and negative correlations among the variables under the Mn supply and UV radiation conditions. These findings clearly display a positive effect of external Mn up to 100μM in the nutrient solution on the resistant of M. aquatica to UV radiation.

Physiological, biochemical and molecular responses of Mentha aquatica L. to manganese

Mentha aquatica is an aromatic herb which possesses valuable terpenoids constituents. Here, we intended to evaluate the effects of the different manganese (Mn) concentrations on the physiological, biochemical and molecular responses in M. aquatica. Basic Hoagland's solution (control), 40, 80, and 160 μM of Mn supplied as MnSO₄·H₂O were applied to the nutrient solution. The results indicated that the different concentrations of Mn differently affected the physiological, biochemical and molecular responses in M. aquatica. The growth parameters (biomass and photosynthetic pigments) and expression levels of β-caryophyllene synthase (CPS), limonene synthase (Ls), geranyl diphosphate synthase (Gpps), and menthofuran synthase (Mfs) genes were increased at the moderate Mn concentrations (40 and 80 μM) and began to decrease at the higher levels. However, the contents of anthocyanins, flavonoids, malonaldehyde (MDA) and hydrogen peroxide (H₂O₂), Mn accumulation, activities of antioxidant enzymes, yield of essential oils and the expression levels of 1-Deoxy d-xylulose-5-phosphate synthase (Dxs) and isopentenyl diphosphate isomerase (Ippi) genes were gradually increased with increasing concentration of Mn in the nutrient solution. Also, the content and chemical composition of terpenoid constituents were altered in the Mn-treated plants. Here, we suggest that the application of external Mn in nutrient solution elevates the growth and expression levels of the genes that are involved in the terpenoid biosynthesis pathway in M. aquatica. Nevertheless, the extent and stability of these growth and gene expression elevation are varied among the different Mn treatments.