Physiological responses of maca (Lepidium meyenii Walp.) plants to UV radiation in its high-altitude mountain ecosystem

Response and Adaptive Mechanism of Flavonoids in Pigmented Potatoes at Different Altitudes

Altitude is an important ecological factor affecting plant physiology and ecology, material metabolism and gene expression. Tuber color changes were observed in purple and red potatoes growing at four different elevations ranging from 1,800 ± 50 to 3,300 ± 50 m in the Tiger Leaping Gorge area of Yunnan Province. The results showed that the total phenol content, total flavone content, total anthocyanin content and biological yield of anthocyanin increased with increasing altitude until 2,800 ± 50 m, and the highest anthocyanin content were detected in the purple potato Huaxinyangyu and the red potato Jianchuanhong at the flowering stage and budding stage, respectively. Combined transcriptomic and metabolomic analyses revealed that the content and diversity of flavonoids are associated with genes expression via the promotion of propane metabolism to improve potato adaptation to different altitudes. These results provide a foundation for understanding the coloring mechanism and creating new potato germplasms with high resistance and good quality via genetic manipulation.

Not All Maca Is Created Equal: A Review of Colors, Nutrition, Phytochemicals, and Clinical Uses

Maca (Lepidium meyenii, Lepidium peruvianum) is part of the Brassicaceae family and grows at high altitudes in the Peruvian Andes mountain range (3500-5000 m). Historically, it has been used as a nutrient-dense food and for its medicinal properties, primarily in enhancing energy and fertility. Scientific research has validated these traditional uses and other clinical applications by elucidating maca's mechanisms of action, nutrition, and phytochemical content. However, research over the last twenty years has identified up to seventeen different colors (phenotypes) of maca. The color, hypocotyl size, growing location, cultivation, and post-harvest processing methods can have a significant effect on the nutrition content, phytochemical profile, and clinical application. Yet, research differentiating the colors of maca and clinical applications remains limited. In this review, research on the nutrition, phytochemicals, and various colors of maca, including black, red, yellow (predominant colors), purple, gray (lesser-known colors), and any combination of colors, including proprietary formulations, will be discussed based on available preclinical and clinical trials. The gaps, deficiencies, and conflicts in the studies will be detailed, along with quality, safety, and efficacy criteria, highlighting the need for future research to specify all these factors of the maca used in publications.

Anti-Inflammation and Anti-Melanogenic Effects of Maca Root Extracts Fermented Using Lactobacillus Strains

Maca is a well-known biennial herb with various physiological properties, such as antioxidant activity and immune response regulation. In this study, the antioxidant, anti-inflammatory, and anti-melanogenic effects of fermented maca root extracts were investigated. The fermentation was carried out using Lactobacillus strains, such as Lactiplantibacillus plantarum subsp. plantarum, Lacticaseibacillus rhamnosus, Lacticaseibacillus casei, and Lactobacillus gasseri. In RAW 264.7 cells, the non-fermented maca root extracts increased the secretion of nitric oxide (NO), an inflammatory mediator, in a dose-dependent manner. In contrast, the fermented extracts showed considerably lower NO secretion than the non-fermented extracts at concentrations of 5% and 10%. This indicates the effective anti-inflammatory effects of fermented maca. The fermented maca root extracts also inhibited tyrosinase activity, melanin synthesis, and melanogenesis by suppressing MITF-related mechanisms. These results show that fermented maca root extracts exhibit higher anti-inflammatory and anti-melanogenesis effects than non-fermented maca root extracts. Thus, maca root extracts fermented using Lactobacillus strains have the potential to be used as an effective cosmeceutical raw material.

Nootropic Herbs, Shrubs, and Trees as Potential Cognitive Enhancers

Plant-based nootropics are a diverse group of natural drugs that can improve cognitive abilities through various physiological mechanisms, especially in cases where these functions are weakened or impaired. In many cases, the nootropics enhance erythrocyte plasticity and inhibit aggregation, which improves the blood's rheological properties and increases its flow to the brain. Many of these formulations possess antioxidant activity that protects brain tissue from neurotoxicity and improves the brain's oxygen supply. They can induce the synthesis of neuronal proteins, nucleic acids, and phospholipids for constructing and repairing neurohormonal membranes. These natural compounds can potentially be present in a great variety of herbs, shrubs, and even some trees and vines. The plant species reviewed here were selected based on the availability of verifiable experimental data and clinical trials investigating potential nootropic effects. Original research articles, relevant animal studies, meta-analyses, systematic reviews, and clinical trials were included in this review. Selected representatives of this heterogeneous group included Bacopa monnieri (L.) Wettst., Centella asiatica (L.) Urban, Eleutherococcus senticosus (Rupr. & Maxim.) Maxim., Ginkgo biloba L., Lepidium meyenii Walp., Panax ginseng C.A. Meyer, Paullinia cupana Kunth, Rhodiola rosea L., Schisandra chinensis (Turcz.) Baill., and Withania somnifera (L.) Dunal. The species are depicted and described, together with their active components and nootropic effects, and evidence of their efficacy is presented. The study provides brief descriptions of the representative species, their occurrence, history, and the chemical composition of the principle medicinal compounds, with uses, indications, experimental treatments, dosages, possible side effects, and contraindications. Most plant nootropics must be taken at optimal doses for extended periods before measurable improvement occurs, but they are generally very well tolerated. Their psychoactive properties are not produced by a single molecule but by a synergistic combination of several compounds. The available data suggest that including extracts from these plants in medicinal products to treat cognitive disorders can have substantial potential therapeutic benefits.

Exploring the Physiological Multiplicity of Native Microalgae from the Ecuadorian Highland, Italian Lowland and Indoor Locations in Response to UV-B

The differential effects of UV-B on the inhibition or activation of protective mechanisms to maintain cells photosynthetically active were investigated in native microalgae. Four strains were used, including two Chlorella sorokiniana strains, F4 and LG1, isolated from a Mediterranean inland swamp and a recycled cigarette butt's substrate, respectively, and two isolates from an Ecuadorian highland lake related to Pectinodesmus pectinatus (PEC) and Ettlia pseudoalveolaris (ETI). Monocultures were exposed to acute UV-B (1.7 W m^-2) over 18 h under controlled conditions. UV-B-untreated microalgae were used as the control. Comparative physiological responses, including photosynthetic pigments, non-enzymatic antioxidants, and chlorophyll a fluorescence, were evaluated at specific time points. Results showed that UV-B significantly compromised all the physiological parameters in F4, thereby resulting in the most UV-B-sensitive strain. Contrarily, UV-B exposure did not lead to changes in the PEC physiological traits, resulting in the best UV-B-resistant strain. This could be attributed to the acclimation to high light habitat, where maintaining a constitutive phenotype (at the photosynthetic level) is strategically advantageous. Differently, LG1 and ETI at 12 h of UV-B exposure showed different UV-B responses, which is probably related to acclimation, where in LG1, the pigments were recovered, and the antioxidants were still functioning, while in ETI, the accumulation of pigments and antioxidants was increased to avoid further photodamage. Consequently, the prolonged exposure in LG1 and ETI resulted in species-specific metabolic regulation (e.g., non-enzymatic antioxidants) in order to constrain full photoinhibition under acute UV-B.

Alchemilla monticola Opiz. Functional Traits Respond to Diverse Alpine Environmental Conditions in Karavanke, Slovenia

Alpine plants are exposed to demanding environmental conditions, such as high ultraviolet (UV) and photosynthetic radiation, extreme temperatures, drought, and nutrient deficiencies. Alpine plants adapt and acclimate to harsh conditions, developing several strategies, including biochemical, physiological, and optical responses. However, alpine plants’ survival strategies are hardly researched due to time-consuming and complex experimental conditions, which are supported by scarce studies. Our study focused on the functional traits of the alpine plant Alchemilla monticola Opiz (hairy lady’s mantle) growing at two different altitudes (1500, 2000 m a.s.l.) and two different UV exposures per altitude. Near-ambient (UV) and reduced (UV-) UV radiations were provided by using two sorts of UV absorbing filters; temperatures were monitored hourly. The experimental plots were located at Tegoška Gora, Karavanke, Slovenia. Functional traits: physiological, biochemical, and optical characteristics were recorded three times during the growing season. A. monticola showed high maximum photochemical efficiency at both altitudes throughout the season, which confirms good adaptation and acclimatization of the plant. Furthermore, significantly higher maximum photochemical efficiency at the subalpine altitude coincided with significantly higher UV absorbing compounds (UV AC) contents at the subalpine compared to the montane altitude in August. A. monticola manifested high UV AC contents throughout the season, with significantly increased synthesis of UV AC contents in the subalpine conditions in August and September. The stomatal conductance rate increased with altitude and was correlated mostly to a lower temperature. A. monticola leaves did not transmit any UV spectrum, which corresponded to high total UV AC contents. The leaf transmittance of the photosynthetic spectrum increased at the subalpine altitude, while the transmittance of the green and yellow spectra increased under the reduced UV radiation in the autumn. A. monticola’s high photosynthetic spectrum transmittance at the subalpine altitude in the autumn might therefore be due to subalpine harsh environmental conditions, as well as plant ontogenetical phase.

UV-B Irradiation Effect on Microalgae Performance in the Remediation of Effluent Derived from the Cigarette Butt Cleaning Process

In this study, the potential of ultraviolet B (UV-B) radiation to alleviate the effects of pollutants in cigarette butt wastewater (CBW) was investigated using different Chlorella sorokiniana strains (F4, R1 and LG1). Microalgae were treated with UV-B (1.7 W m⁻²) for 3 days prior to their exposure to CBW and then incubated for 4 days in the absence or presence of UV-B. UV-B-untreated microalgae were used as the control. Comparative physiological responses, including photosynthetic pigments and non-enzymatic antioxidants, as well as nicotine and nicotyrine removal, were evaluated in 7-day cultures. UV-B treatments did not negatively impact algal chlorophyll or carotenoid production. UV-B acclimation was strain-dependent, correlating with native environment adaptations and genetic constitutions. UV-B as a pretreatment had long-term positive effects on non-enzymatic antioxidant capacity. However, LG1 needed more time to readjust the pro-oxidant/antioxidant balance, as it was the most UV-B-sensitive. Phenolic compounds played an important role in the antioxidant system response to UV-B, while flavonoids did not contribute to the total antioxidant capacity. Although cross-resistance between UV-B and CBW was observed in F4 and R1, only R1 showed nicotine/nicotyrine catabolism induction due to UV-B. Overall, the results suggest that UV-B activates defense pathways associated with resistance or tolerance to nicotine and nicotyrine.

Pharmaceutical Potential of High-Altitude Plants for Fatigue-Related Disorders: A Review

Natural plants from plateaus have been the richest source of secondary metabolites extensively used in traditional and modern health care systems. They were submitted to years of natural selection, co-evolved within that habitat, and show significant anti-fatigue-related pharmacological effects. However, currently, no review on high-altitude plants with anti-fatigue related properties has been published yet. This study summarized several Chinese traditional high-altitude plants, including Rhodiola rosea L., Crocus sativus L., Lepidium meyenii W., Hippophaerhamnoides L., which are widely used in the Qinghai–Tibet Plateau and surrounding mountains, as well as herbal markets in the plains. Based on phytopharmacology studies, deeper questions can be further revealed regarding how these plants regulate fatigue and related mental or physical disease conditions. Many active derivatives in high-altitude medical plants show therapeutic potential for the management of fatigue and related disorders. Therefore, high-altitude plants significantly relieve central or peripheral fatigue by acting as neuroprotective agents, energy supplements, metabolism regulators, antioxidant, and inflammatory response inhibitors. Their applications on the highland or flatland and prospects in natural medicine are further forecast, which may open treatments to reduce or prevent fatigue-related disorders in populations with sub-optimal health.

Chemical fingerprinting of the Brazilian medicinal plant Calea pinnatifida (R. Br.) Less. (Asteraceae) collected at different altitudes

Calea pinnatifida (R. Br.) Less. is a plant of Brazilian folk medicine. We evaluated the influence of environmental factors on the chemical profile of C. pinnatifida collected during the winter season. C. pinnatifida leaves, alongside soil samples, were collected from two sites of different altitude. Plant samples were sequentially extracted, while soil samples were subject to compositional analysis. Plant extracts were compared using HPTLC-UV, using chemometric analyses to compare samplings harvested at both altitudes. Two marker metabolites, calein A (1) and acetylportentol (2), were isolated from samples collected at the respective altitudes. The differing metabolic profiles observed may be a result of the influence of environmental factors.

Integrated Metabolomic and Transcriptomic Analysis of the Flavonoid Accumulation in the Leaves of Cyclocarya paliurus at Different Altitudes

Cyclocarya paliurus is a medicinal plant containing flavonoids, triterpenoids, polyphenolics, polysaccharides, and other compounds with diverse biological functions. C. paliurus is distributed across altitudes ranging from 400 to 1,000 m. However, little is known about the effect of altitude on metabolite accumulation in C. paliurus. Also, the biosynthetic pathway involved in flavonoid accumulation in C. paliurus has not been fully elucidated. In this study, mature leaves of C. paliurus growing at low altitude (280 m) and high altitude (920 m) were sampled and subjected to metabolomic and transcriptomic analyses. The flavonoid content and composition were higher in the leaves of C. paliurus collected at high altitude than in those collected at low altitude. Most of the differentially accumulated metabolites (DAMs) were enriched in "flavone and flavonol biosynthesis." The significant differentially expressed genes (DEGs) between low and high altitudes were mainly enriched in "biological process." The most heavily enriched KEGG pathway was related to the subcategory "Oxidative phosphorylation," indicating that complicated biological processes are involved in the response of C. paliurus to harsh environmental factors. High UV-light might be the main influencing factor among the harsh environmental factors found in high altitudes. Integrated analysis of metabolomic and transcriptomic data showed that 31 flavonoids were significantly correlated with 227 DEGs, resulting in 412 related pairs (283 positive and 129 negative) between the DEGs and flavonoids. The possible mechanisms underlying the differentially accumulation of flavonoids at different altitude might be due to variations in transport and relocation of flavonoids in C. paliurus leaves, but not different flavonoid biosynthesis pathways. The up-regulation of genes related to energy and protein synthesis might contribute to flavonoid accumulation at high altitudes. This study broadens our understanding of the effect of altitude on metabolite accumulation and biosynthesis in C. paliurus.

Variation in Amygdalin Content in Kernels of Six Almond Species (Prunus spp. L.) Distributed in China

Amygdalin, a naturally occurring compound, is one of the main active ingredients of the Chinese raw bitter almond. The variation in amygdalin composition of seed kernels among the six almond species was determined, and relationships with geoenvironmental factors were analyzed. The amygdalin content exhibited great diversity, ranging from 0.0004 to 9.73 g/100 g. The highest level of amygdalin was detected in Tangut almond, with 5.45-9.73 g/100 g. The other kernels showed a range from 3.14 to 6.80 g/100 g in wild almond and from 3.00 to 4.22 g/100 g in longstalk almond. Amygdalin in common almond was almost undetectable. Factor analysis showed that amygdalin content in Prunus spp. kernels increased with altitude and decreased with the degree of aspect. Many environmental factors were closely related to amygdalin content, including annual precipitation (Bio12), UV intensity, and topsoil base saturation (T_BS), which all had a significant effect on amygdalin content. The amygdalin content is closely related to rainfall indicators, especially annual precipitation (Bio12), with the highest factor analysis value (3.63). Water regulates amygdalin in diverse ways. Since amygdalin is water-soluble, water can reduce the inhibitory effect of amygdalin on germination and regulate the synthesis of amygdalin at the late stage of germination by activating the amygdalin synthesis genes CYP79D16 and CYP71AN24. This study expands the understanding of amygdalin in almond resources and provides the direction for the regulation of amygdalin.

Altitudinal Variation of Metabolites, Mineral Elements and Antioxidant Activities of Rhodiola crenulata (Hook.f. & Thomson) H.Ohba

Rhodiolacrenulata (Hook.f. & Thomson) H.Ohba is an alpine medicinal plant that can survive in extreme high altitude environments. However, its changes to extreme high altitude are not yet clear. In this study, the response of Rhodiola crenulata to differences in altitude gradients was investigated through chemical, ICP-MS and metabolomic methods. A targeted study of Rhodiola crenulata growing at three vertical altitudes revealed that the contents of seven elements Ca, Sr, B, Mn, Ni, Cu, and Cd, the phenolic components, the ascorbic acid, the ascorbic acid/dehydroascorbate ratio, and the antioxidant capacity were positively correlated with altitude, while the opposite was true for total ascorbic acid content. Furthermore, 1165 metabolites were identified: flavonoids (200), gallic acids (30), phenylpropanoids (237), amino acids (100), free fatty acids and glycerides (56), nucleotides (60), as well as other metabolites (482). The differential metabolite and biomarker analyses suggested that, with an increasing altitude: (1) the shikimic acid-phenylalanine-phenylpropanoids-flavonoids pathway was enhanced, with phenylpropanoids upregulating biomarkers much more than flavonoids; phenylpropanes and phenylmethanes upregulated, and phenylethanes downregulated; the upregulation of quercetin was especially significant in flavonoids; upregulation of condensed tannins and downregulation of hydrolyzed tannins; upregulation of shikimic acids and amino acids including phenylalanine. (2) significant upregulation of free fatty acids and downregulation of glycerides; and (3) upregulation of adenosine phosphates. Our findings provide new insights on the responses of Rhodiola crenulata to extreme high altitude adversity.

Hormonal Regulation in Different Varieties of Chenopodium quinoa Willd. Exposed to Short Acute UV-B Irradiation

Increased ultraviolet-B (UV-B) due to global change can affect plant development and metabolism. Quinoa tolerates extreme conditions including high UV levels. However, the physiological mechanisms behind its abiotic stress tolerance are unclear, especially those related to UV-B. We previously demonstrated that 9.12 kJ m⁻² d⁻¹ may induce UV-B-specific signaling while 18.24 kJ m⁻² d⁻¹ promotes a UV-B-independent response. Here, we explored the effects of these UV-B doses on hormonal regulation linked to plant morphology and defense among diverse varieties. Changes in fluorescence parameters of photosystem II, flavonoids and hormones (indoleacetic acid (IAA), jasmonic acid (JA), abscisic acid (ABA) and salicylic acid (SA)) were surveyed under controlled conditions. Here, we showed that the sensitivity to short acute UV-B doses in varieties from different habitats is influenced by their parental lines and breeding time. UV-B sensitivity does not necessarily correlate with quinoa’s geographical distribution. The role of flavonoids in the UV-B response seems to be different depending on varieties. Moreover, we found that the extent of changes in JA and SA correlate with UV-B tolerance, while the increase of ABA was mainly related to UV-B stress.

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

This assessment by the Environmental Effects Assessment Panel (EEAP) of the United Nations Environment Programme (UNEP) provides the latest scientific update since our most recent comprehensive assessment (Photochemical and Photobiological Sciences, 2019, 18, 595-828). The interactive effects between the stratospheric ozone layer, solar ultraviolet (UV) radiation, and climate change are presented within the framework of the Montreal Protocol and the United Nations Sustainable Development Goals. We address how these global environmental changes affect the atmosphere and air quality; human health; terrestrial and aquatic ecosystems; biogeochemical cycles; and materials used in outdoor construction, solar energy technologies, and fabrics. In many cases, there is a growing influence from changes in seasonality and extreme events due to climate change. Additionally, we assess the transmission and environmental effects of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is responsible for the COVID-19 pandemic, in the context of linkages with solar UV radiation and the Montreal Protocol.

Short review on recent progress in Mn4+ -activated oxide phosphors for indoor plant light-emitting diodes

In the modern era, growing number of indoor plants for various purposes, such as vegetation, flowering, and decorations, has increased over the traditional follow-up trends for plantation. However, the indoor plantation requires different parameters for their growth; among these, light plays a significant role. In order to control the growth of plants using light-emitting diodes, Mn-doped oxide phosphors have emerged as promising candidates due to their broad and intense emission bands in the red and far-red spectral range. In this review article, recent progress on Mn-doped oxides for indoor plant growth has been reviewed. This review article is mainly divided into three parts. In the first part, different reaction conditions for the synthesis of Mn-doped oxide phosphors are compared. In the second part, the luminescent and other photometric parameters of these are discussed. The influence of different co-dopants on the luminescent characteristics has been elucidated in detail. The third part discusses the properties of light-emitting diodes fabricated using these phosphors for plant growth. The present review article elucidates the synthesis parameters, luminescent properties, and light-emitting diodes fabricated using Mn-doped oxide materials for plant growth applications.

Browning, Starch Gelatinization, Water Sorption, Glass Transition, and Caking Properties of Freeze-dried Maca ( Lepidium meyenii Walpers) Powders

The browning, gelatinization of starch, water sorption, glass transition, and caking properties of freeze-dried maca ( Lepidium meyenii Walpers) powders were investigated and compared with a commercial maca powder. The freeze-dried maca powders had lower optical density (browning) and higher enthalpy change for starch gelatinization than the commercial maca. This resulted from a difference in thermal history. The equilibrium water contents of the freeze-dried maca powders were higher than those of commercial maca at each water activity ( a w ) because of differences in amorphous part. The glass transition temperature ( T g ) was evaluated by differential scanning calorimetry. There was a negligible difference in the anhydrous T g (79.5-80.2 ºC) among the samples. The T g -depression of freeze-dried maca powders induced by water sorption was more gradual than that of the commercial maca due to a difference in water insoluble material content. From the results, critical water activity ( a wc ) was determined as the a w at which T g becomes 25 ºC. There was negligible caking below a w = 0.328. At higher a w , the degree of caking remarkably increased with a large variation depending on the samples. The degree of caking could be described uniformly as a function of a w / a wc . From these results, we propose an empirical approach to predict the caking of maca powders.