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.

Macamide, a component of maca (Lepidium meyenii Walp) lipophilic extract, enhances myogenic differentiation via AKT/p38 signaling and attenuates dexamethasone-induced muscle atrophy.

Maca (Lepidium meyenii) is a plant that grows in the central Andes region of Peru, and it has been reported to have various bioactive functions, such as improving or preventing osteoporosis, sexual dysfunction, and memory impairment. In this study, maca roots of various colors (yellow, red, or black) were extracted using different polar solvents (PE, HEX, or BuOH) to compare their effects on muscle differentiation. Among them, the red maca lipophilic extract, which showed the most effectiveness, was chosen for further investigation. Our results show that RMLE enhances muscle differentiation by inducing MyoD-E2A heterodimerization through the activation of the AKT/p38 pathway. Additionally, RMLE attenuated dexamethasone-induced muscle atrophy by inhibiting nuclear translocation of FoxO3a and expression of E3-ligase (MAFbx and MURF1) in vitro and in vivo. Therefore, based on these results suggest that lipophilic extract of maca, which can abundantly contain nonpolar compounds, macamides, can enhance the functional properties of maca in alleviating muscle homeostasis.

Incorporation of Lepidium perfoliatum seed gum into wheat starch affects its physicochemical, viscoelastic, pasting and freeze-thaw syneresis properties.

This study aimed to investigate the influence of incorporating Lepidium perfoliatum seed gum (LPSG) into wheat starch (WS) at various mixing ratios on its FTIR, DSC, steady and dynamic rheological properties, pasting attributes, syneresis, and particle size distributions characteristics. The interaction between WS and LPSG was purely based on hydrogen-bonding. It was found that the onset (To) and peak (Tp) temperatures of the LPSG-rich mixtures increased by 10 % and 8 %, respectively, while the enthalpy (ΔH) decreased by 70 % compared to WS. A higher LPSG ratio led to a decrease in the frequency dependence of storage modulus (G'), as well as an increase in the pseudoplasticity of the mixtures. The in-shear structural recovery test showed that the rate of recovery (R, %) increased with an increasing LPSG ratio. The pasting results demonstrated that the 9/1 ratio had the highest final viscosity and the lowest relative breakdown. Applying 1 to 5 freeze-thaw cycles resulted in a 50 % to 70 % decrease in syneresis for the 9/1 mixing ratio in comparison to WS, respectively. The incorporation of LPSG into WS resulted in higher static and dynamic magnitudes of yield stress, as well as an increase in particle size when compared to WS.

Effect of Maca aqueous extract addition to a freezing extender for canine semen.

This study investigated the effect of the addition of Lepidium meyenii (Maca) to the freezing extender on the post-thaw quality of dog semen. Ten canine ejaculates were frozen following a two-step protocol using a tris-glucose-citrate egg yolk extender with or without the addition of 10 µl/mL of aqueous extract of Maca (Maca and ctrl groups, respectively). Prior to (fresh semen) and after freezing (T0) sperm motility, kinetic parameters, viability and mitochondrial membrane potential (MMP), as well as the levels of malondialdehyde (MDA) were evaluated. In addition, sperm motility, kinetic parameters, viability and MMP were examined up to 2 h of incubation of 37 °C after thawing (T1 and T2) to evaluate thermo-resistance. The addition of Maca reduced MDA concentration at T0 (p < 0.05) and increased total motility, the percentage of sperm with medium velocity and WOB at T1. Progressive motility decreased (p < 0.05) at T1 in the ctrl group, whereas it was not affected in Maca group at any time point. In addition, the percentage of hyperactivated spermatozoa remained constant at T1 in the ctrl, while in the Maca group an increase (p < 0.05) of this parameter was recorded. Although no differences were found for MMP between groups at any time points, a decrease of viable sperm with low MMP was observed in ctrl group between T0 and T1 and in Maca group between T1 and T2. The addition of Maca prior freezing reduced the extent of lipid peroxidation and activated canine sperm motility and hyperactivation after thawing.

Maca roots: A potential therapeutic in the management of metabolic disorders through the modulation of metabolic biochemical markers in rats fed high-fat high-carbohydrate diet.

ETHNOPHARMACOLOGICAL RELEVANCE: Maca root (Lepidium meyenii Walp.) is a Peruvian plant of the Brassicaceae family. Maca roots are popular food supplements used to treat a variety of ailments described traditionally as enhancing metabolic and health conditions. AIM OF THE STUDY: Metabolic syndrome (MetS) has been the real scourge globally, affecting more than one-fourth of the global population. MetS causes the development of multi-organ illnesses, including altered blood cholesterol and sugar levels, oxidative stress, and hypertension. This study evaluated maca root total methanolic extract (MTE) as a potential nutraceutical to manage the complications of MetS. MATERIALS AND METHODS: After the first 4 weeks of a high-fat high-carbohydrate diet (HFCD), streptozotocin (STZ) was injected in Wistar rats to induce the MetS model. Animals were treated orally with MTE at 100 mg/kg and 300 mg/kg for 4 weeks compared to metformin at 200 mg/kg after confirmation of diabetes. RESULTS: One month of MTE supplementation in HFCD-fed rats remarkably decreased the elevation of blood glucose and lipids, improved liver function and insulin resistance, additionally it successfully restored the state of inflammatory and oxidative stress. The extract was standardized to contain total phenolics equal to 24.45 ± 0.96 µg Gallic acid/mg extract. CONCLUSIONS: Our findings suggest that MTE improves MetS by reducing hyperglycemia, hyperlipidemia, inflammation, and oxidative stress. While also improving beta cell secretory functions, implying that MTE could be used as a balancing drug in the prevention and treatment of metabolic abnormalities linked to type 2 diabetes.

Development of oral formulation of Lepidium seeds significantly decreases the high blood glucose levels in diabetic rats: in vitro formulation and in vivo antidiabetic performance.

BACKGROUND: Lepidium sativum, Garden Cress (GC), seeds have a lot of natural molecules with a pronounced activity against different disorders. It was reported that GC seeds have the ability to lower the blood glucose level. AIM: The aim of this work was to formulate GC seeds into oral tablets containing a fixed dose of the grounded seeds. Furthermore, the anti-diabetic performance of the prepared tablets was studied in the streptozotocin rats' model in comparison with positive control metformin. METHODS: Micrometrics of GC grounded seeds with different excipients were investigated. Then, GC tablets were prepared via direct compression technique. GC tablets were characterized for their uniformity of dosage unit, friability, hardness, disintegration time, and in vitro release. The antidiabetic effect was studied in rats for a period of 28 days. Glycosylated hemoglobin, liver performance, and lipid levels include total cholesterol (TC), triglycerides (TGs), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) were also estimated. In addition, histopathological study of liver and pancreas was also performed. RESULTS: Prosolv®EasyTab produced tablets with higher hardness, lower disintegration time, and fast release. GC tablets significantly lower the elevated blood glucose level. In addition, they have antihyperlipidemic activity, hepatocellular protective role and restore the histology of the liver and pancreas. CONCLUSION: GC tablets could be a promising alternative formulation to control the high blood glucose level in diabetic rats rather than chemically derivatized drugs.

Downregulation of the INDEHISCENT Gene by RNAi Resulted in Desired Pod Shatter Reduction of Lepidium campestre in Subsequent Generations.

Wild species field cress (Lepidium campestre) has favorable agronomic traits, making it a good candidate for future development as an oil and catch crop. However, the species is very prone to pod shatter, resulting in severe yield losses. This is one of the important agronomic traits that needs to be improved in order to make this species economically viable. In this study, we cloned the L. campestre INDEHISCENT (LcIND) gene and prepared two LcIND-RNAi constructs with the IND promoter (long 400 bp and short 200 bp) from Arabidopsis. A number of stable transgenic lines were developed and evaluated in terms of pod shatter resistance. The majority of the transgenic lines showed increased resistance to pod shatter compared to the wild type, and this resistance was maintained in four subsequent generations. The downregulation of the LcIND gene by RNAi in the transgenic lines was confirmed by qRT-PCR analysis on T3 lines. Southern blot analysis showed that most of the analyzed lines had a single-copy integration of the transgene, which is desirable for further use. Our results show that it is possible to generate stable transgenic lines with desirable pod shatter resistance by downregulating the LcIND gene using RNAi in field cress, and thus speeding up the domestication process of this wild species.

2-phenylacetamide Separated from the seed of Lepidium apetalum Willd. inhibited renal fibrosis via MAPK pathway mediated RAAS and oxidative stress in SHR Rats.

BACKGROUND: Renal fibrosis with Renin-angiotensin-aldosterone system (RAAS) activation and oxidative stress are one of the major complications in hypertension. 2-phenylacetamide (PA), a major active component of Lepidium apetalum Willd. (L.A), has numerous pharmacological effects. Its analogues have the effect of anti-renal fibrosis and alleviating renal injury. This study aims to explore the underlying mechanism of PA for regulating the renal fibrosis in SHR based on the MAPK pathway mediated RAAS and oxidative stress. METHODS: The SHR rats were used as the hypertension model, and the WKY rats were used as the control group. The blood pressure (BP), urine volume were detected every week. After PA treatment for 4 weeks, the levels of RAAS, inflammation and cytokines were measured by Enzyme-Linked Immunosorbnent Assay (ELISA). Hematoxylin-Eosin staining (HE), Masson and Immunohistochemistry (IHC) were used to observe the renal pathology, collagen deposition and fibrosis. Western blot was used to examine the MAPK pathway in renal. Finally, the SB203580 (p38 MAPK inhibitor) antagonism assay in the high NaCl-induced NRK52e cells was used, together with In-Cell Western (ICW), Flow Cytometry (FCM), High Content Screening (HCS) and ELISA to confirm the potential pharmacological mechanism. RESULTS: PA reduced the BP, RAAS, inflammation and cytokines, promoted the urine, and relieved renal pathological injury and collagen deposition, repaired renal fibrosis, decreased the expression of NADPH Oxidase 4 (NOX4), transforming growth factor-ß (TGF-ß), SMAD3 and MAPK signaling pathway in SHR rats. Meanwhile,,the role of PA could be blocked by p38 antagonist SB203580 effectively in the high NaCl-induced NRK52e cells. Moreover, molecular docking indicated that PA occupied the ligand binding sites of p38 MAPK. CONCLUSION: PA inhibited renal fibrosis via MAPK signalling pathway mediated RAAS and oxidative stress in SHR Rats.

Macathioureas A-D, four new thiourea analogues from the roots of Lepidium meyenii.

Macathioureas A-D (1-4), four new thiourea derivatives with a carbamothioylpyrrolidine-2-carboxamide framework, were isolated from the roots of Lepidium meyenii (Maca) collected from Qujing, Yunnan Province of China. Their structures were identified based on extensive spectroscopic data, including 1D NMR, 2D NMR, and HRESIMS techniques. Their absolute configurations were assigned as 7S by the comparison of the experimental and predicted electronic circular dichroism (ECD) spectra. All the thiourea analogues were tested for their cytotoxicities against five human cancer cell lines. However, no significant activities were detected at concentrations up to 40 µM.

The Efficient Synthesis and Anti-Fatigue Activity Evaluation of Macamides: The Unique Bioactive Compounds in Maca.

Macamides are a class of amide alkaloids that are only found in maca and are widely considered to be its bioactive marker compounds. More than thirty macamide monomers have been identified in recent years; however, it is difficult to obtain a single macamide monomer from the maca plant because of their similar structures and characteristics. We used the carbodiimide condensation method (CCM) to efficiently synthesize five typical macamides, including N-benzyl-hexadecanamide (NBH), N-benzyl-9Z,12Z,15Z-octadecenamide, N-(3-methoxybenzyl)-9Z,12Z-octadecenamide, N-benzyl-9Z,12Z-octadecenamide, and N-(3-methoxybenzyl)-9Z,12Z,15Z-octadecadienamide. All the synthesized macamides were purified by a one-step HPLC with a purity of more than 95%. NBH is the most abundant macamide monomer in natural maca, and it was selected to evaluate the anti-fatigue effects of macamides. The results indicated that NBH could enhance the endurance capacity of mice by increasing liver glycogen levels and decreasing blood urea nitrogen, lactate dehydrogenase, blood ammonia, and blood lactic acid levels. Macamides might be the active substances that give maca its anti-fatigue active function.

UPLC-QE-Orbitrap-Based Cell Metabolomics and Network Pharmacology to Reveal the Mechanism of N-Benzylhexadecanamide Isolated from Maca (Lepidium meyenii Walp.) against Testicular Dysfunction.

Testicular dysfunction (TDF) is characterized by testosterone deficiency and is caused by oxidative stress injury in Leydig cells. A natural fatty amide named N-benzylhexadecanamide (NBH), derived from cruciferous maca, has been shown to promote testosterone production. Our study aims to reveal the anti-TDF effect of NBH and explore its potential mechanism in vitro. This study examined the effects of H2O2 on cell viability and testosterone levels in mouse Leydig cells (TM3) under oxidative stress. In addition, cell metabolomics analysis based on UPLC-Q-Exactive-MS/MS showed that NBH was mainly involved in arginine biosynthesis, aminoacyl-tRNA biosynthesis, phenylalanine, tyrosine and tryptophan biosynthesis, the TCA cycle and other metabolic pathways by affecting 23 differential metabolites, including arginine and phenylalanine. Furthermore, we also performed network pharmacological analysis to observe the key protein targets in NBH treatment. The results showed that its role was to up-regulate ALOX5, down-regulate CYP1A2, and play a role in promoting testicular activity by participating in the steroid hormone biosynthesis pathway. In summary, our study not only provides new insights into the biochemical mechanisms of natural compounds in the treatment of TDF, but also provides a research strategy that integrates cell metabolomics and network pharmacology in order to promote the screening of new drugs for the treatment of TDF.

Stage-specific metabolomics suggests a trade-off between primary and secondary metabolites for nutritional advantage in Lepidium latifolium L.

Lepidium latifolium L. is an established phytofood of the Ladakh Himalayas that contains differential content of important glucosinolates (GLS) in specific stages of sprouts. Therefore, in order to harness its nutraceutical potential, a comprehensive mass spectrometry-based stage-specific untargeted metabolomic analysis was performed. A total of 318 metabolites were detected, out of which 229 were significantly (p ≤ 0.05) changed during different stages. The Principal Component Analysis plot clearly differentiated different growth stages into three clusters. The nutritionally important metabolites, including amino acids, sugars, organic acids, and fatty acids, were found significantly (p ≤ 0.05) higher in the first cluster consisting of 1st, 2nd and 3rd week sprouts. The higher energy requirements during the early growth stages were observed with the higher metabolites of glycolysis and the TCA cycle. Further, the trade-off between primary and secondary sulfur-containing metabolites was observed, which may explain the differential GLS content in different growth stages.

Effect of Black Maca Supplementation on Inflammatory Markers and Physical Fitness in Male Elite Athletes.

Given the current lack of studies, the primary purpose of this study was to investigate the effects of black maca supplementation intake on changes in physical strength and inflammatory markers among elite athletes. Forty-four elite athletes were recruited for the present study. They included shooting athletes, racket sports athletes, and fin swimming athletes. The intake capsules contained 2500 mg of 100% concentrated black maca extract. Participants were instructed to take one capsule twice a day for eight weeks with pure water. Changes were seen in the ATP-PC systems and aerobic energy systems, particularly in the fin swimming athletes requiring aerobic energy systems. This effect is caused by increased antioxidant activity and influenced mitochondrial biosynthesis regulatory factors due to black maca supplementation intake. These findings provide preliminary evidence that elite athletes will benefit from taking black maca to improve their inflammation levels and physical fitness.

Two new flavonoid thioglucosides from the seeds of Lepidium apetalum.

Two previously undescribed flavonoid thioglucosides lepidiumflavonosides A and B (1-2) and two known megastigmane compounds (7E,9S)-9-hydroxy-5,7-megastigmadien-4-one 9-O-ß-D-glucopyranoside (3) and (9S)-4-oxo-ß-inol ß-D-glucopyranoside (4) were isolated from the water extract of the seeds of Lepidium apetalum Willd. The structural elucidation of isolated compounds was unambiguously determined based on extensive 1D and 2D NMR spectroscopic analyses. All compounds were evaluated for their estrogen-like effects on MCF-7 cells in vitro. The results showed that compounds 1-4 significantly promoted the proliferation of MCF-7 cells, and the proliferation was antagonized by the specific ER antagonist ICI182,780, suggesting that compounds 1-4 might have the estrogen-like effect in vitro potentially.

Stem cell induction and plant regeneration are affected by medium components in maca (Lepidium meyenii Walp).

BACKGROUND: In medicinal plants, selection, reproduction and preservation of important genotypes are very necessary. Nowadays, using tissue culture and regeneration techniques of medicinal plants under in vitro conditions has been able to proliferate medicinal plants widely, which is much higher than traditional methods of vegetative propagation. Maca (Lepidium meyenii), is an industrial plant whose root is the usable part. Maca has valuable medicinal effects such as sexual enhancement and reproductive power, infertility treatment, improved sperm count and quality, anti-stress, osteoporosis prevention and more. METHODS AND RESULTS: This study was conducted to induce callus and regeneration of Maca. First, MS medium supplemented with different concentrations of Kinetin, Naphthaleneacetic acid and 2,4-Dichlorophenoxyacetic acid [0.5, 1 and 2 µM respectively] and control were compared for callus induction from root and leaves. After 38 days of incubation, the first callus appeared, after 50 days of callus induction and after 79 days regeneration occurred. The callus induction experiment was performed for the study of the effect of three explants (leaf, stem and root) and seven hormone levels. The regeneration experiment was carried out by studying the effect of three explants (leaf, stem and root) on eight levels of the hormone. The results of data analysis on callus induction showed that the effects of explants, hormones and their interactions on callus induction percentage were highly significant but not significant on callus growth rate. The results of regression analysis showed that explants, hormones and their interactions had no significant effect on regeneration percentage. CONCLUSION: Based on our results, the best medium for inducing callus was Hormone 2,4-D [2 µM] and Kinetin [0.5 µM], in which the highest percentage of callus induction was in leaf explants (62%). And the lowest were in stem (30%) and root (27%) explants. According to the comparison of the mean, the best environment for regeneration of the environment was 4 µM 6-Benzylaminopurine 2.5 + Thidiazuron, in which the highest percentage of regeneration was in leaf explant (87%) and stem (69%) and the lowest in root explant (12). %).

Effect of maca (Lepidium meyenii) extract on non-obstructive azoospermia in male mice.

ETHNOPHARMACOLOGICAL RELEVANCE: Maca (Lepidium meyenii) is a medicinal and edible plant that has a long history attention because of its potential to improve fertility and sexual function. AIM OF STUDY: In this study, effects of maca on azoospermia were investigated. The effective components of maca were screened. MATERIALS AND METHODS: The therapeutic action of maca were evaluated in a busulfan-induced azoospermic model. RESULTS: It was found that maca could alleviate the vacuolation of spermatogenic tubules and testicular lesions, promote the recovery of spermatogenic epithelium, inhibit the proliferation of stromal cells, significantly increase the serum testosterone content, and improve the number and quality of sperm. Maca extract was then divided into polysaccharides, oligosaccharides and small molecules fractions for preliminary screening of efficacy. These results showed that there was no significant difference between the maca polysaccharide fraction and maca extract. CONCLUSIONS: The results were shown that maca can improve non-obstructive azoospermia, the polysaccharide fraction was the active components.

Reprotoxicity induced by acute exposure to aqueous tuber extract of Peruvian Maca (Lepidium meyenii Walp.) in Caenorhabditis elegans.

Maca (Lepidium meyenii Walp.) has been used in folk medicine to treat fertility disturbances, a claim that has been evidenced in some studies. However, the clinical trials validating this use have shown paradoxical findings and then maca safety is not well known. This study investigated the effects and mechanisms by which maca affects the reproductive system using an in vivo model, the nematode Caenorhabditis elegans. Tuber maca powder, obtained from local commerce, was used to prepare the aqueous extract. Worms were acutely exposed to maca extracts (40, 120, 240, and 330 µg/µl), and 48 h after treatments, physiological and biochemical assays were conducted. Maca extract caused a significant decrease in total number of eggs and in the number of eggs per worm. These effects were associated to increased lipid peroxidation, reduced triacylglycerol levels, and also impaired vit-2 (vitellogenin) expression, besides increase in the number of apoptotic germline cells. We have found quantifiable levels of alkaloids in this maca extract, which presence could be related to this toxicity. Collectively, our data suggest that maca extract exposure causes reproductive toxicity to worms that could be, at least in part, associated to both an increase in apoptosis of germline cells and also to a decrease in vitellogenin expression, needed for egg yolk production and, consequently, successful reproduction.

The benefits of Maca (Lepidium meyenii) extract administration for male rabbits affected by environmental heat stress.

Heat stress (HS) is the most substantial environmental issue in rabbit health status impairment, which can lower productivity. Maca is a common medicinal plant with important biological activities including antioxidant, anti-inflammatory, anti-fatigue, and neuroprotective effects. The present research explored the alleged protective role of Maca extract in alleviating the adverse impact of HS on rabbits. Growing V-line 6-week-old buck rabbits (N = 48) were orally administered Maca extract at levels of 0 (MAC0), 200 (MAC2), 400 (MAC4), or 600 (MAC6) mg/head twice per week. Compared to the control groups, rabbits provided Maca had better growth performance, feed intake and feed conversion ratio. Liver and tests weights were significantly higher (p < 0.05) in Maca treated groups compared to the control. hemoglobin, white blood cell, red blood corpuscles, platelet count, hematocrit, and lymphocytes were significantly increased in the MAC4 group compared with the control group. MAC4 treatment significantly reduced aspartate aminotransferase and malondialdehyde levels compared with other groups. Moreover, the concentrations of total bilirubin, creatinine, glucose, total cholesterol, and triglycerides were lower (p < 0.05) in the MAC4 group than in the controls. Oral administration of Maca improved cortisol and testosterone values, total antioxidant capacity, and superoxide dismutase. The MAC4 group exhibited significant improvement (p < 0.05) in sperm motility, survival, membrane functionality, concentration, and libido, with a significant decrease in abnormal sperm compared with the control group. Also, aforementioned group showed sperm cells with a normal structure and intact plasma membranes, acrosomes, and well-organised axonemal components. Histopathological screening of liver sections showed moderate to severe degenerative and necrotic changes in rabbits exposed to HS, which were alleviated with Maca oral administration. In conclusion, oral administration of Maca extract at 400 or 600 mg/head-weekly enhanced growth performance, hemato-biochemical attributes, antioxidant status, and semen quality in rabbits during the hot season.

A comparative study of the chloroplast genomes of five Lepidium species with high medicinal value.

Plantgenomics is a rapidly developing field in medicinal plant research. This study analysed the relevant information of chloroplasts genome sequences of five medicinal plants from the genus Lepidium . We sequenced the complete chloroplast (cp) genomes of Lepidium apetalum Willd. and Lepidium perfoliatum Linnaeus., and assessed their genetic profiles against the reported profiles of Lepidium sativum Linnaeus., Lepidium meyenii Walp., and Lepidium virginicum Linn. We found that L. apetalum and L. perfoliatum possessed 130 distinct genes that included 85 protein-coding, 37 transfer RNA (tRNA), and eight ribosomal RNA (rRNA) genes. Our repeat analyses revealed that L. apetalum harboured 20 direct repeats, 16 palindrome repeats, 30 tandem repeats, and 87 simple sequence repeats, whereas, L. perfoliatum had 15 direct repeats, 20 palindrome repeats, four reverse repeats, 21 tandem repeats, and 98 simple sequence repeats. Using syntenic analysis, we also revealed a high degree of sequence similarity within the coding regions of Lepidium medicinal plant cp genomes, and a high degree of divergence among the intergenic spacers. Pairwise alignment and single-nucleotide polymorphism (SNP) examinations further revealed certain Lepidium -specific gene fragments. Codon usage analysis showed that codon 14 was the most frequently used codon in the Lepidium coding sequences. Further, correlation investigations suggest that L. apetalum and L. perfoliatum originate from similar genetic backgrounds. Analysis of codon usage bias of Lepidium cp genome was strongly influenced by mutation and natural selection. We showed that L. apetalum and L. perfoliatum will likely enhance breeding, species recognition, phylogenetic evolution, and cp genetic engineering of the Lepidium medicinal plants.

Diverse responses of halophyte and glycophyte Lepidium species to the salt-mediated amelioration of nickel toxicity and accumulation.

Tolerance mechanisms employed by plants under environmental stresses can protect them against other co-occurring stresses. In this study, the effect of pre-exposure and simultaneous salt treatment on nickel (Ni) toxicity tolerance in one halophyte (L. sativum) and one glycophyte (L. latifolium) Lepidium species in hydroponics was investigated. In order to compare the species independent from their salt and Ni tolerance level, the glycophyte was subjected to lower salt and Ni concentrations and for a shorter period of time than the halophyte. Salt (NaCl) was applied at 50 and 100 mM concentrations and Ni was provided at an equal free Ni2+ activity by adding 100 and 200 µM Ni as single stresses, but 130 and 300 µM Ni for the treatment of its combination with salt in the glycophyte and halophyte, respectively. Temporal analyses of signaling molecules revealed that the halophyte is characteristically different from the glycophyte in that it exhibits a higher constitutive level of nitric oxide and hydrogen peroxide, a longer duration of response to Ni, and its augmentation by salt. In addition to higher biomass and less Ni accumulation in salt-treated plants, the concentrations of free thiol groups, leaf pigments, proline, free and cell wall-bound phenolics contents, and the activity of phenolic metabolizing enzymes were higher in L. latifolium under the combined salt and Ni treatments than under the single Ni stress. In contrast, the biomass and most biochemical parameters of Ni-stressed L. sativum plants were not enhanced by salt treatment but rather decreased. Our findings shed light on cross-tolerance mechanisms in halophytes and uncovered halophyte survival strategies under multiple stresses.