High altitude plants, chemistry of acclimation and adaptation

Antioxidant activity of Zuccagnia-type propolis: A combined approach based on LC-HRMS analysis of bioanalytical-guided fractions and computational investigation

This study reports a combined approach to assess the antioxidant activity of Zuccagnia-type propolis. Fractions exhibiting the highest antioxidant activities evidenced by DPPH, a β-carotene bleaching and superoxide radical scavenging activity-non-enzymatic assays, were processed by LC-HRMS/MS to characterize the relevant chemical compounds. A computational protocol based on the DFT calculations was used to rationalize the main outcomes. Among the 28 identified flavonoids, caffeic acids derivatives were in the fraction exhibiting the highest antioxidant activity, with 1-methyl-3-(4'-hydroxyphenyl)-propyl caffeic acid ester and 1-methyl-3-(3',4'-dihydroxyphenyl)-propyl caffeic acid ester as major components. Results clearly showed roles of specific chemical motifs, which can be supported by the computational analysis. This is the first report ascribing the antioxidant ability of Zuccagnia-type propolis to its content in specific caffeic acid derivatives, a potential source of radical scavenging phytochemicals. The proposed protocol can be extended to the study of other plant-products to address the most interesting bioactive compounds.

High-Altitude Medicinal Plants as Promising Source of Phytochemical Antioxidants to Combat Lifestyle-Associated Oxidative Stress-Induced Disorders

Oxidative stress, driven by reactive oxygen, nitrogen, and sulphur species (ROS, RNS, RSS), poses a significant threat to cellular integrity and human health. Generated during mitochondrial respiration, inflammation, UV exposure and pollution, these species damage cells and contribute to pathologies like cardiovascular issues, neurodegeneration, cancer, and metabolic syndromes. Lifestyle factors exert a substantial influence on oxidative stress levels, with mitochondria emerging as pivotal players in ROS generation and cellular equilibrium. Phytochemicals, abundant in plants, such as carotenoids, ascorbic acid, tocopherols and polyphenols, offer diverse antioxidant mechanisms. They scavenge free radicals, chelate metal ions, and modulate cellular signalling pathways to mitigate oxidative damage. Furthermore, plants thriving in high-altitude regions are adapted to extreme conditions, and synthesize secondary metabolites, like flavonoids and phenolic compounds in bulk quantities, which act to form a robust antioxidant defence against oxidative stress, including UV radiation and temperature fluctuations. These plants are promising sources for drug development, offering innovative strategies by which to manage oxidative stress-related ailments and enhance human health. Understanding and harnessing the antioxidant potential of phytochemicals from high-altitude plants represent crucial steps in combating oxidative stress-induced disorders and promoting overall wellbeing. This study offers a comprehensive summary of the production and physio-pathological aspects of lifestyle-induced oxidative stress disorders and explores the potential of phytochemicals as promising antioxidants. Additionally, it presents an appraisal of high-altitude medicinal plants as significant sources of antioxidants, highlighting their potential for drug development and the creation of innovative antioxidant therapeutic approaches.

A Synopsis of Dicranum Hedw. (Dicranaceae, Bryophyta) in China, with Special References to Four Species Newly Reported and Re-Evaluation of Dicranum psathyrum Klazenga

Dicranum Hedw. is a highly diverse and widely distributed genus within Dicranaceae. The species diversity and distribution of this genus in China, however, remain not well known. A new revision of Dicranum in China using morphological and molecular phylogenetic methods confirms that China has 39 species, including four newly reported species, D. bardunovii Tubanova & Ignatova, D. dispersum Engelmark, D. schljakovii Ignatova & Tubanova, and D. spadiceum J.E.Zetterst. Dicranum psathyrum Klazenga is transferred to Dicranoloma (Renauld) Renauld as a new synonym of Dicranoloma fragile Broth. Two species, Dicranum brevifolium (Lindb.) Lindb. and D. viride (Sull. & Lesq.) Lindb. are excluded from the bryoflora of China. A key to the Chinese Dicranum species is also provided. These results indicate an underestimation of the distribution range of numerous Dicranum species, underscoring the need for further in-depth investigations into the worldwide Dicranum diversity.

UBC Gene Family Analysis in Salvia castanea and Roles of ScUBC2/5 Genes under Abiotic Stress

Salvia castanea Diels, a relative of the medicinal plant Salvia miltiorrhiza Bunge, belongs to the genus Salvia and family Lamiaceae. Ubiquitin-conjugating enzyme E2 (UBC) is an important ubiquitin-binding enzyme in protein ubiquitination. This study aimed to analyze the regulatory role of UBC genes, particularly ScUBC2/5, on the growth and adaptation of S. castanea to extreme environments including cold or drought stress. We identified nine UBC genes in S. castanea and found that these genes were extremely stable and more highly expressed in the roots than other tissues. This suggested that UBC genes might play a role in promoting root adaptation to cold and dry environments. Further analysis of UBC gene expression in hairy roots under cold (4 °C) and UV stress also confirmed their importance under stress. The contents of tanshinone and salvianolic acid in hairy roots with the overexpression of ScUBC2/5 were increased compared to non-transgenic wild type, and the cold and UV resistance of hairy roots was increased compared with that of wild type. Together, these findings highlighted the role of ScUBC2/5 in enhancing secondary metabolite accumulation and regulation in response to cold and ultraviolet stress in S. castanea, providing a new perspective for genetic improvement in its phytochemistry.

Seeding alpine grasses in low altitude region increases global warming potential during early seedling growth

Introduction of alpine grasses to low altitude regions has long been a crucial strategy for enriching germplasm diversity, cultivating and acclimating high-quality species, enhancing ecosystem resilience and adaptability, as well as facilitating ecosystem restoration. However, there is an urgent need to investigate the impacts of planting Gramineae seeds on greenhouse gas (GHG) emissions, particularly during the critical stage of early plant growth. In this study, four species of grass seeds (Stipa breviflora, Poa pratensis, Achnatherum splendens, Elymus nutans) were collected from 19 high-altitude regions surrounding the Qinghai-Tibet Plateau and sown at low-altitude. Measurements of GHG emissions at early seedling growth in the mesocosm experiment using static chamber method showed a strong increase in the cumulative emissions of CO2 (5.71%-9.19%) and N2O (11.36%-13.64%) (p < 0.05), as well as an elevated CH4 uptake (2.75%-5.50%) in sites where the four grass species were introduced, compared to bare soil. Consequently, there was a substantial rise in global warming potential (13.87%-16.33%) (p < 0.05) at grass-introduced sites. Redundancy analysis showed that seed traits, plant biomass, and seedling emergence percentage were the main driving biotic factors of three GHGs fluxes. Our study unveils the potential risk of escalating GHG emissions induced by introducing high altitude grasses to low altitude bare soil, elucidating the mechanism through linking seed traits with seedling establishment and environmental feedback. Furthermore, this offers a new perspective for assessing the impact of grass introduction on ecological environment of introduced site.

A promising blueberry from Colombia: antioxidant activity, nutritional and phytochemical composition of Cavendishia nitida (Kunth) A.C.Sm

Many Neotropical representatives of Ericaceae have fruits with antioxidant activity and high nutritional value. However, in Colombia, these fruits are little consumed and are considered underutilized. One such example is the berries of Cavendishia nitida (Kunth) A.C.Sm. In this study, the nutritional value, the total phenolic, flavonoid and anthocyanin contents, and antioxidant activity of C. nitida fruit were performed. From the leaves, an ethanolic extract was made, which was then fractioned to measure its antioxidant activity and analyze its chemical composition. The results indicate that the fruit of C. nitida can be classified as potentially edible, due to its minerals and vitamins contents. Five anthocyanins were detected in the berries; while in the leaves extract six terpenes and one flavonol were identified. The ethyl acetate fraction of the leaves extract exhibited strong antioxidant activity with the DPPH^• and ABTS^•+ radicals tested. We also found a strong correlation between the total phenolic and flavonoid contents and the values of percentage of inhibition of DPPH^• and ABTS^•+ in all the samples tested. The results of this study suggest that the berries of C. nitida are promising as edible fruits, and beneficial for human and animal health. However, even though the communities of the region use this berry as food, the toxicity of fruits must be evaluated to confirm that their consumption is safe for humans.

Edaphic Factors Influence the Distribution of Arbuscular Mycorrhizal Fungi Along an Altitudinal Gradient of a Tropical Mountain

Changes in relief in montane areas, with increasing altitude, provide different biotic and abiotic conditions, acting on the species of arbuscular mycorrhizal fungi (AMF). The objective of this work was to determine the influence of altitude, edaphic factors, and vegetation on the AMF species in a mountainous area. The list of AMF species was obtained from morphological identification of the spores, with 72 species recovered from field samples and trap cultures. Lower levels of Shannon's diversity occurred only at lower altitude; however, there was no difference in AMF richness. The structure of the AMF assembly between the two highest altitudes was similar and differed in relation to the lower altitude. There was variation in the distribution of AMF species, which was related to soil texture and chemical factors along the altitude gradient. Some species, genera, and families were indicative of a certain altitude, showing the preference of fungi for certain environmental conditions, which may aid in decisions to conserve montane ecosystems.

Comparison of Natural Regeneration in Natural Grassland and Pine Plantations across an Elevational Gradient in the Páramo Ecosystem of Southern Ecuador

During the 1980s, reforestation programs using exotic species (Pinus spp.) were established in the páramo ecosystem of Ecuador. The aims of this study were: (1) to compare the natural regeneration between pine plantations (Pi) and natural grassland (NG) across an elevational gradient and (2) to identify the attributes of Pi and soil properties that were influencing herbaceous and woody plant composition and their plant cover. In total, six independent Pinus patula (Schltdl. & Cham. plantations (two per each elevation) were selected and distributed in an elevational range (3200–3400, 3400–3600, 3600–3800 m a.s.l.). Adjacent to Pi, plots in NG were established for recording natural regeneration. Both, namely the attributes and the soil samples, were measured in Pi. The results showed that natural regeneration differs significantly between both types of vegetation. As expected, NG holds more plant diversity than Pi; the elevational range showed a clear tendency that there was more herbaceous richness when elevation range increases, while the opposite was found for woody species. Moreover, attributes of Pi influenced herbaceous and woody vegetation, when saturated hydraulic conductivity (Ksat) in the soil, basal area (BA) and canopy density (CD) increased, herbaceous species richness and its cover decreseased; and when Ksat and the acidity in the soil increased, woody plants richness and its cover decreased. The plantations have facilitated the establishment of shade tolerant species. More studies are needed to evaluate if removal with adequate management of pine plantations can improve the restoration and conservation of the native vegetation of the páramo ecosystem.

Alternative splicing coupled to nonsense-mediated mRNA decay contributes to the high-altitude adaptation of maca (Lepidium meyenii)

Alpine plants remain the least studied plant communities in terrestrial ecosystems. However, how they adapt to high-altitude environments is far from clear. Here, we used RNA-seq to investigate a typical alpine plant maca (Lepidium meyenii) to understand its high-altitude adaptation at transcriptional and post-transcriptional level. At transcriptional level, we found that maca root significantly up-regulated plant immunity genes in day-time comparing to night-time, and up-regulated abiotic (cold/osmotic) stress response genes in Nov and Dec comparing to Oct. In addition, 17 positively selected genes were identified, which could be involved in mitochondrion. At post-transcriptional level, we found that maca had species-specific characterized alternative splicing (AS) profile which could be influenced by stress environments. For example, the alternative 3' splice site events (A3SS, 39.62%) were predominate AS events in maca, rather than intron retention (IR, 23.17%). Interestingly, besides serine/arginine-rich (SR) proteins and long non-coding RNAs (lncRNAs), a lot of components in nonsense-mediated mRNA decay (NMD) were identified under differential alternative splicing (DAS), supporting AS coupled to NMD as essential mechanisms for maca's stress responses and high-altitude adaptation. Taken together, we first attempted to unveil maca's high-altitude adaptation mechanisms based on transcriptome and post-transcriptome evidence. Our data provided valuable insights to understand the high-altitude adaptation of alpine plants.

Nutritional composition, antioxidant activity and isolation of scopoletin from Senecio nutans: support of ancestral and new uses

Continuing with our study characterising Senecio nutans Sch. Bip., we have isolated and identified a simple coumarin, scopoletin, that could be relevant for the biological properties of the species related with the ancestral medical uses. This is the first report of scopoletin from S. nutans. In addition, the extract was analysed for its antioxidant activity using the ABTS and FRAP method as well as providing the first nutritional analyses of this plant from northern Chile highlands.

Freezing resistance in Patagonian woody shrubs: the role of cell wall elasticity and stem vessel size

Freezing resistance through avoidance or tolerance of extracellular ice nucleation is important for plant survival in habitats with frequent subzero temperatures. However, the role of cell walls in leaf freezing resistance and the coordination between leaf and stem physiological processes under subzero temperatures are not well understood. We studied leaf and stem responses to freezing temperatures, leaf and stem supercooling, leaf bulk elastic modulus and stem xylem vessel size of six Patagonian shrub species from two sites (plateau and low elevation sites) with different elevation and minimum temperatures. Ice seeding was initiated in the stem and quickly spread to leaves, but two species from the plateau site had barriers against rapid spread of ice. Shrubs with xylem vessels smaller in diameter had greater stem supercooling capacity, i.e., ice nucleated at lower subzero temperatures. Only one species with the lowest ice nucleation temperature among all species studied exhibited freezing avoidance by substantial supercooling, while the rest were able to tolerate extracellular freezing from -11.3 to -20 °C. Leaves of species with more rigid cell walls (higher bulk elastic modulus) could survive freezing to lower subzero temperatures, suggesting that rigid cell walls potentially reduce the degree of physical injury to cell membranes during the extracellular freezing and/or thaw processes. In conclusion, our results reveal the temporal-spatial ice spreading pattern (from stem to leaves) in Patagonian shrubs, and indicate the role of xylem vessel size in determining supercooling capacity and the role of cell wall elasticity in determining leaf tolerance of extracellular ice formation.

Comparative study of antioxidant and anti-inflammatory activities and genotoxicity of alcoholic and aqueous extracts of four Fabiana species that grow in mountainous area of Argentina

ETHNOPHARMACOLOGICAL RELEVANCE

Fabiana species (Solanaceae family) extracts have long been used in Argentinean traditional medicine as anti-inflammatories, antiseptic, bone fractures and others diseases, but there is no scientific evidence which supports their use.

AIM OF THE STUDY

The present study was conducted to evaluate the ability of aqueous and ethanolic extracts of four Fabiana species (Fabiana bryoides Phil., Fabiana punensis A.C. Arroyo, Fabiana densa J. Rèmy and Fabiana patagonica Speg.) to inhibit key enzymes in inflammatory processes, free radical scavenging properties and genotoxic effects.

MATERIALS AND METHODS

HPLC-DAD of aqueous and ethanolic extracts from four Fabiana species was established. All Fabiana extracts were evaluated on their ability to inhibit hyaluronidase and lipoxygenase enzymes to assess their activity against inflammatory mediators. Antioxidant capacity was determined using the 2,2'-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging assays and β-carotene-linolenic acid assay. Genotoxicity was evaluated by the Ames assay.

RESULTS

The results indicated that the chromatographic patterns of four Fabiana species were different in quantity and absorption intensity of peaks. The alcoholic extract of Fabiana punensis was the most active scavenger of DPPH and ABTS(+) radicals (SC(50) values of 3.85 ± 0.24 and 2.56 ± 0.10 μgGAE/mL, respectively). Fabiana patagonica extracts exhibited the highest peroxyl radical scavenging activity compared with the other three taxa (IC(50) values between 1.00 ± 0.04 and 4.46 ± 0.40 μg GAE/mL for all extracts) and anti-lipoxygenase activity with IC(50) values between 12.5 and 15.5 μg GAE/mL. The absence of mutagenicity indicates that the DNA does not seem to be a relevant target for these extracts. Fabiana bryoides ethanolic extract showed an interesting effect: it inhibited spontaneous mutagenesis, which could be considered as an antimutagenic effect in the TA98 (+S9) and TA100 (+S9/-S9) strains. The potency differences found between the species could be consequence of the different phytochemical pattern observed by HPLC.

CONCLUSIONS

The inhibitory effects on lipoxygenase and hyaluronidase, free radical scavenging activities and lack of genotoxicity of Fabiana extracts may support the folk use of Fabiana punensis, Fabiana patagonica, Fabiana bryoides and Fabiana densa as inhibitor of inflammatory mediators.