Species Lepidium Research Articles

Revisiting the bicontinental allopolyploid origin of Australasian Lepidium species with amplicon sequencing of 15 nuclear genes

New Zealand is home to 16 endemic species of Lepidium (Brassicaceae), including two species considered to have become extinct since European colonisation and an additional species shared with Australia. Previous meiotic chromosome counts suggest at least some are high polyploids. A hybrid origin has been proposed for several of them, with African and American species implicated as parents. We generated amplicon sequence data for 15 genes derived from targeted enrichment data from a selection of species endemic to New Zealand, and of African, American, and Australian origin naturalised in New Zealand. These were analysed, along with publicly available genomic data from other Lepidium species. Our results are consistent with earlier work in supporting two main groups of endemic New Zealand Lepidium, corresponding to different dominant nrDNA sequences. Our data suggest that these two groups differ in ploidy (one octoploid, the ploidy of the other uncertain). The octoploid species combine four distinguishable subgenomes and the other species may be the products of allopolyploidisation between octoploid species and a diploid species closely related to, if not, L. africanum. Previously proposed links to American Lepidium are also supported, with at least two Australasian Lepidium subgenomes related to subgenomes present in American polyploid species. The affinities of two further subgenomes present in Australasian Lepidium remain to be determined, but they may also be of American origin. One New Zealand endemic species, L. naufragorum, displays sequences broadly consistent with it being the octodecaploid product of hybridisation between octoploid and decaploid New Zealand groups.

The pattern of declines and local extinctions of endemic inland Lepidium species in the eastern South Island

The pattern of declines and local extinctions of endemic inland Lepidium species in the eastern South Island

Taxonomic review of Lepidium ruderale (Brassicaceae) in Korea

The current status of Lepidium ruderale L. is uncertain in Korea. This alien species was previously reported as a new record of the Korean flora and placed under L. ruderale. Although some taxonomists have suggested that it belongs to another Lepidium taxon, no conclusions have been reached. Therefore, in this study, the holotype and protologue of L. ruderale were obtained and carefully examined. The description of this species is as follows: basal leaves are 1–3 pinnate; cauline leaf blades are linear to lanceolate and entire and ciliate; petals are absent or rudimentary; flowers have two stamens; and fruits are winged at the apex, have an apical notch, and are glabrous. These features distinguish it from other Lepidium species. Examination of numerous specimens and analysis of multiple characteristics demonstrated that the voucher specimens of L. ruderale belong to L. pinnatifidum Ledeb. Therefore, L. ruderale is not distributed in Korea.

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 100mM concentrations and Ni was provided at an equal free Ni2+ activity by adding 100 and 200µM Ni as single stresses, but 130 and 300µM 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.

Comparative transcriptomics identifies candidate genes involved in the evolutionary transition from dehiscent to indehiscent fruits in Lepidium (Brassicaceae)

BackgroundFruits are the seed-bearing structures of flowering plants and are highly diverse in terms of morphology, texture and maturation. Dehiscent fruits split open upon maturation to discharge their seeds while indehiscent fruits are dispersed as a whole. Indehiscent fruits evolved from dehiscent fruits several times independently in the crucifer family (Brassicaceae). The fruits of Lepidium appelianum, for example, are indehiscent while the fruits of the closely related L. campestre are dehiscent. Here, we investigate the molecular and genetic mechanisms underlying the evolutionary transition from dehiscent to indehiscent fruits using these two Lepidium species as model system.ResultsWe have sequenced the transcriptomes and small RNAs of floral buds, flowers and fruits of L. appelianum and L. campestre and analyzed differentially expressed genes (DEGs) and differently differentially expressed genes (DDEGs). DEGs are genes that show significantly different transcript levels in the same structures (buds, flowers and fruits) in different species, or in different structures in the same species. DDEGs are genes for which the change in expression level between two structures is significantly different in one species than in the other. Comparing the two species, the highest number of DEGs was found in flowers, followed by fruits and floral buds while the highest number of DDEGs was found in fruits versus flowers followed by flowers versus floral buds. Several gene ontology terms related to cell wall synthesis and degradation were overrepresented in different sets of DEGs highlighting the importance of these processes for fruit opening. Furthermore, the fruit valve identity genes FRUITFULL and YABBY3 were among the DEGs identified. Finally, the microRNA miR166 as well as the TCP transcription factors BRANCHED1 (BRC1) and TCP FAMILY TRANSCRIPTION FACTOR 4 (TCP4) were found to be DDEGs.ConclusionsOur study reveals differences in gene expression between dehiscent and indehiscent fruits and uncovers miR166, BRC1 and TCP4 as candidate genes for the evolutionary transition from dehiscent to indehiscent fruits in Lepidium.

Maca could improve endurance capacity possibly by increasing mitochondrial biogenesis pathways and antioxidant response in exercised rats.

The objective of this study was to shed light on the effect of a novel Lepidium peruvianum (Maca) blend on anti-fatigue capacities in exercised rats. Twenty-eight male albino rats were allocated into four groups (n=7) at random: (i) Control (vehicle), (ii) Maca: (40 mg/kg/BW), (iii) WL-FST: weight-loaded forced swimming test group, and (iv) WL-FST + Maca group. Maca supplementation increased swimming time to exhaustion (p < .01), while decreased serum lactate and liver glycogen concentrations. Maca addition resulted in lower levels of serum, liver, and muscle MDA (p < .05). Muscle GPx activity increased in both Maca groups (p < .001). Moreover, NF-κB levels were less in the WL-FST + Maca compared to the WL-FST group (p < .001). Nrf1, Nrf2, PGC-1α, SIRT1, and TFAM levels were augmented in the WL-FST + Maca compared to the WL-FST (p < .05). Consequently, our Maca blend increased endurance capacity and prevented exercise-induced oxidative stress and lactic acid buildup. PRACTICAL APPLICATIONS: The brassica species Lepidium peruvianum (maca) has been consumed in Peru for centuries to enhance mood, libido, and energy. Although the positive effects of this plant on energy metabolism are accredited, the underlying molecular mechanisms of these effects have not been sufficiently elucidated. The current study's findings suggest that this innovative, exclusive maca powder blend can boost endurance while preventing oxidative stress and lactic acid buildup during acute exercise. The mechanism of this efficacy is thought to be caused by maca's regulatory properties on energy metabolism signaling receptors and strong antioxidant scavenging effects on the free radicals that are produced by prolonged exhaustive exercise periods.

Zincum Metallicum, a homeopathic drug, alleviates Zn-induced toxic effects and promotes plant growth and antioxidant capacity in Lepidium sativum L.

In this study, we investigated the effect of the homeopathic drug Zincum Metallicum (ZM) on zinc (Zn) toxicity in the plant species Lepidium sativum L. We focused on growth parameters, Zn uptake and numerous biochemical parameters. Seedlings were hydroponically subjected during 7days to 0.05, 500, 1000, 1500 and 2000µM Zn2+, in the absence or presence of 15ch or 9ch ZM. In the absence of ZM, Zn induced negative effect on growth especially at the dose of 2mM. Zn induced also chlorosis, reduced total chlorophyll and/or carotenoid content and increased the level of malondialdehyde (MDA). Under Zn toxicity (500, 1000 and 1500µM), the superoxide dismutase (SOD), catalase (CAT), gaiacol peroxidase (GPX) and glutathione reductase (GR) activities were increased or not significantly affected, while at 2000µM Zn affected the activity of these enzymes. At the highest Zn level (2mM), proline and total polyphenol and flavonoid contents were markedly increased in leaves and roots of L. sativum. Additionally, ZM supply considerably ameliorated the plant growth, photosynthetic pigment contents and increased non-enzymatic antioxidant molecules and enzymatic activities against Zn-induced oxidative stress. Our data suggest that homeopathic properties of ZM may be efficiently involved in the restriction of Zn-induced oxidative damages, by lowering Zn accumulation and translocation in the leaves and roots of Lepidium sativum L.

Lepidium oblongum (Brassicaceae) appeared on Hungarian railways: the beginning of a wider European conquest?

Lepidium oblongum, of American origin is a new member of the European adventive flora, only detected in Romania so far. The first Hungarian stand was discovered in 2018, and others in 2020. Based on our studies, we detail its morphological characteristics in comparison with other Lepidium species. We present a new drawing and a table to help identify the species. Lepidium oblongum is easily identifiable by its divided (lobed or lobed-dentated) upper stem leaves. By analyzing selected climatic parameters we show that the new European habitats are found in the drier and cooler summer subtype of the humid continental climate belt. In Hungary, it spreads directly along the railways. The establishment of individual populations can be influenced by the location of cargo unloading and the movement of railway workers. Lepidium oblongum occupies gravelly, sun-exposed habitats along Hungarian railway tracks such as loading platforms, guardhouses and goods stations. Based on its high stress and climatic tolerance and initial spread-rate, it is consider to be a naturalized member of the European adventive flora, that could be potentially invasive along the European railways.

Genetic analysis of Lepidium spp. by SSR and ISSR molecular markers

Simple sequence repeat (SSR) and inter simple sequence repeat (ISSR) markers were employed to evaluate the genetic diversity and population structure of 22 accessions belonging to three Lepidium species. Results revealed a high level of genetic diversity in the Lepidium accessions. A total of 58 bands were amplified by 11 ISSR primers, of which all were polymorphic, while 11 SSR primers produced 30 bands, of which 27 (90.0%) were polymorphic. The average values of polymorphism information content (PIC), marker index (MI), effective multiplex ratio (EMR) and percentage of polymorphic loci (PPL) in the ISSR markers were higher than those in SSRs, whereas higher values of number of effective alleles (Ne) and Shannon's information index (I) were observed by SSR markers. Based on the number of observed alleles (Na), Ne, I, expected heterozygosity (He) and PPL, the highest genetic diversity was found in L.draba followed by L.sativum by both markers. The analysis of molecular variance showed that higher allelic diversity within species than among species. The 22 Lepidium accessions grouped into three main clusters based on neighbor-joining (NJ) clustering and principal coordinate analysis (PCoA), and three (ISSR) or four (SSR and pooled data) sub-populations based on STRUCTURE analysis independent of their taxonomy. This is the first report of genetic diversity and relationships among accessions of L.sativum, L.draba and L. latifolium using SSR and ISSR markers. Therefore, these results can be utilized to improve these Lepidium species for various desired traits through molecular and hybridization breeding techniques.

Lepidium sativum: A potential functional food

Lepidium sativum Linn. (family Cruciferae) is an edible herb that is botanically related to watercress and mustard, having their peppery, tangy taste and odour. Traditionally L. sativum seeds are used to treat wounds, sprains, asthma, bronchitis, cough and is considered useful as abortifacient, aphrodisiac, antibacterial, diuretic, expectorant, gastrointestinal stimulant, gastroprotective, laxative and stomachic. Many of these traditional uses have been scientifically validated using different in vitro and in vivo studies and in this review are compiled in an inclusive manner. Seeds are reported to be rich in carbohydrates, vitamins, amino acids, proteins, triterpenoids, steroids and saponin glycosides possessing different pharmacological activities. Aim of the study: This study is an effort to collate complete scientific literature published till March 2021 in order to generate a succinct summation on the distribution, traditional beneficial potential, chemical constituents, phytochemistry, pharmacology and toxicology of this coveted species of genus Lepidium. Materials and Methods: Exploring assorted scientific databases. Results: The present methodically compiled review article accentuates medicinal and nutritional significance of this highly valued plant by focusing on various aspects of the plant such as the, physicochemical characterisation and pharmacological studies that validates folklore uses. Thus, this annotated script on L. sativum would be a handy tool to explore the future prospective of research on this traditional plant.

Phytochemical investigation, antimicrobial and cytotoxic activities of suspension cultures of Lepidium sativum L.

Lepidium sativum L. family Brassicaceae (Cruciferae) is one of the most recognized Lepidium species in the folk medicine of Africa and the middle east. Its English common name is Garden cress and known as Hab Al-Rashad in north Africa and the Arabian Peninsula. It is well known for a wide range of biological activities and a complex phytochemical composition. The current study investigates tissue culture protocols for L. sativum. For static culture initiation, Murashige and Skooge (MS) as a basal medium for L. sativum leaves was employed. Suspension cultures were initiated from leaf explant calli of L. sativum using media supplemented with various combinations of hormonal supply of 2,4 dichloro phenoxy acetic acid (2,4-D), indole-3- acetic acid (IAA), 1-naphthyl acetic acid (NAA), and adenine. Liquid chromatography/mass spectroscopy (LC/MS) analysis was performed on the ethanolic extracts of plant parts and the produced calli. The LC/MS analysis revealed the presence of eleven secondary metabolites with varying concentrations. The identified compounds are apigenin, quercetin, kaempferol, luteolin and 7-hydroxy-4′,5,6-trimethoxyisoflavone, sinapic acid, chlorogenic acid, p-coumaric acid, ascorbic acid, α-tocopherol and 6-prenylnaringenin. Antimicrobial and cytotoxic activities were evaluated for the calli extracts. In general, superior activities were identified for the produced calli extracts when compared to plant parts’ extracts.

The complete chloroplast genome sequence of Lepidium perfoliatum L.

This study was based on the collection of the complete genome of Lepidium perfoliatum chloroplast (cp). The full cp genome is 154,264 bp long, containing 130 genes, in which 8 genes are specified for ribosomal RNA (rRNA), while 85 and 37 genes for protein-coding and transfer RNA (tRNA) respectively. Phylogenetic analyss revealed the closed cluster of Lepidium perfoliatum with other Lepidium species such as Lepidium apetalum, Lepidium sativum, Lepidium meyenii and Lepidium virginicum, which helps for the evaluation of how Lepidium perfoliatum is phylogenetically related to other species.

Morphologically and physiologically diverse fruits of two Lepidium species differ in allocation of glucosinolates into immature and mature seed and pericarp.

The morphology and physiology of diaspores play crucial roles in determining the fate of seeds in unpredictable habitats. In some genera of the Brassicaceae different types of diaspores can be found. Lepidium appelianum produces non-dormant seeds within indehiscent fruits while in L. campestre dormant seeds are released from dehiscent fruits. We investigated whether the allocation of relevant defence compounds into different tissues in different Lepidium species may be related to the diverse dispersal strategy (indehiscent and dehiscent) and seed physiology (non-dormant and dormant). Total glucosinolate concentration and composition were analysed in immature and mature seeds and pericarps of L. appelianum and L. campestre using high-performance liquid chromatography. Moreover, for comparison, transgenic RNAi L. campestre lines were used that produce indehiscent fruits due to silencing of LcINDEHISCENCE, the INDEHISCENCE ortholog of L. campestre. Total glucosinolate concentrations were lower in immature compared to mature seeds in all studied Lepidium species and transgenic lines. In contrast, indehiscent fruits of L. appelianum maintained their total glucosinolate concentration in mature pericarps compared to immature ones, while in dehiscent L. campestre and in indehiscent RNAi-LcIND L. campestre a significant decrease in total glucosinolate concentrations from immature to mature pericarps could be detected. Indole glucosinolates were detected in lower abundance than the other glucosinolate classes (aliphatic and aromatic). Relatively high concentrations of 4-methoxyindol-3-ylmethyl glucosinolate were found in mature seeds of L. appelianum compared to other tissues, while no indole glucosinolates were detected in mature diaspores of L. campestre. The diaspores of the latter species may rather depend on aliphatic and aromatic glucosinolates for long-term protection. The allocation patterns of glucosinolates correlate with the morpho-physiologically distinct fruits of L. appelianum and L. campestre and may be explained by the distinct dispersal strategies and the dormancy status of both species.

Phylogenetic relationships of two representative Lepidium species (Brassicaceae) in Qinghai province

Phylogenetic relationships of two representative Lepidium species (Brassicaceae) in Qinghai province

Differential functional traits underlying the contrasting salt tolerance in Lepidium species

To explore the mechanisms responsible for salt tolerance in Brassicaceae species, a multifactorial approach was used to clarify the functional traits underlying the differential salt tolerance in two Lepidium species, namely the halophyte L. latifolium and its glycophyte relative, L. sativum. Parameters related to photosynthesis, nitrogen assimilation, ion accumulation, water relations and succulence, osmotic adjustment, phenolics metabolism, antioxidative defense, nitric oxide (NO) level and the expression of Na+ antiporter (SOS1 and NHX) were analyzed in plants grown under salt stress in hydroponics. In addition to significant differences regarding the majority of salt tolerance indicators, a characteristic early boost, 52 h after exposure to salt, was observed in the concentration of H2O2 and NO in the halophyte, which was almost absent in the glycophyte. Following the application of detrended component analysis, discrimination between the glycophyte and halophyte could only be performed via temporal curves in the antioxdative components and NO, and less effectively, by phenolics metabolism. H2O2 and NO signaling and the adaptive modification of phenolics metabolism play crucial roles in determining the halophytic behavior of L. latifolium. These data may result in new insights concerning the studies on halophytism in the Brassicaceae.

Weevil Complexes (Coleoptera, Curculionoidea) Associated with Lepidium crassifolium Waldst. et Kit. and L. coronopifolium Fisch. ex Ledeb. (Brassicaceae) in the Southern Steppe at the Boundary between Europe and Asia

Material of 11 weevil species collected from two halophilic crucifers of the genus Lepidium—L. crassifolium Waldst. et Kit. and L. coronopifolium Fisch. ex Ledeb.—in Orenburg Province (Southern Urals) at the boundary between Europe and Asia is first reported. Six species have been found on L. crassifolium, and seven, on L. coronopifolium. A new species Bruchela uralensis Korotyaev, sp. n. is described from L. coronopifolium; it is similar and apparently closely related to B. kasparyani Kor. from Transcaucasia, associated with Lepidium vesicarium L. Bruchela orientalis (Strejcek, 1982), sp. propria is restored from synonymy with B. kaszabi (Strejcek, 1973), and B. tchitensis Egorov, 1996 is placed in synonymy of the former: Bruchela orientalis (Strejcek, 1982) = B. tchitensis Egorov, 1996, syn. n.Bruchela parvula (Motsch.) is recorded for the first time for Turkmenistan, Tajikistan and Iran. A list of the Palaearctic Lepidium species is provided with which weevils of the genera Ceutorhynchus and Lixus, and the subfamily Baridinae are associated. Three additional Central and Eastern Palaearctic species of Lepidium are recorded as weevil hosts for the first time: L. densiflorum Schrad. with monophagous Ceutorhynchus testatus Faust in southern Siberia and in Mongolia; L. appelianum Al-Shehbaz (= Cardaria pubescens (C.A. Mey.) Jarm.), on which Ceutorhynchus sordidus Faust was found in southern Mongolia, and L. cordatum Willd. ex DC., on which Scaphomorphus vibex (Pallas) was found in southern Tuva.

Ecotoxicological risk assessment of revegetated bauxite residue: Implications for future rehabilitation programmes

Around 3 billion tonnes of bauxite residue (BR), the by-product of alumina extraction, have been produced and stockpiled worldwide, representing a potential risk for the environment due to the high alkalinity and the presence of relatively high concentrations of trace elements. Phytoremediation (or simply revegetation) is regarded as the most promising in situ remediation option to mitigate the environmental risk that might arise from the land-disposal of BR. Rehabilitation strategies (including the incorporation of amendments such as gypsum and organic matter) have been employed to address the main limitations to plant establishment and growth on BR, typically the high alkalinity, salinity and sodicity. However, the potential for trace element uptake and phytotoxicity have been largely unreported in revegetated BRs.In order to assess the ecotoxicological risk, samples of previously revegetated BR were collected from the field, characterized in the laboratory, and used to conduct ex-situ plant bioassays (Phytotoxkit™ and the RHIZOtest). Without rehabilitation, fresh BR severely inhibits seed germinationand root/shoot development in test species Lepidium sativum, Sinapis alba and Sorghum saccharatum. Plant uptake for Al, As, Cr, V was assessed with RHIZOtest bioassay trials with Lolium perenne and demonstrated that plants exposed to fresh BR take up and translocated trace elements to their shoots at concentrations (As = 4.13 mg/kg dm; Cr = 3.29 mg/kg dm; V = 85.66 mg/kg dm) exceeding phytotoxic levels (vanadium) or maximum levels specified for animal feed (arsenic), showing visible stress symptoms in the seedlings.Conversely, revegetated BR show improved chemical properties, allow seed germination, and permits seedling growth with no evidence of trace element phytotoxicity. However, Na can be taken up at concentrations that could elicit phytotoxicity and impair the success of revegetation. For future rehabilitation programmes, direct revegetation on BR after the incorporation of amendments such as gypsum and organic matter is recommended.

Salt tolerance mechanisms in three Irano-Turanian Brassicaceae halophytes relatives of Arabidopsis thaliana.

Salt tolerance mechanisms were studied in three Irano-Turanian halophytic species from the Brassicaceae ‎‎(Lepidium latifolium, L. perfoliatum and Schrenkiella parvula) and compared with the glycophyte Arabidopsis thaliana. According to seed germination under salt stress, L. perfoliatum was the most tolerant species, while L. latifolium and S. parvula were rather susceptible. Contrastingly, based on biomass production L. perfoliatum was more salt sensitive than the other two species. In S. parvula biomass was increased up to 2.8-fold by 100mM NaCl; no significant growth reduction was observed even when exposed to 400mM NaCl. Stable activities of antioxidative defense enzymes, nil or negligible accumulation of superoxide anion and hydrogen peroxide, as well as stable membrane integrity in the three halophytes revealed that no oxidative stress occurred in these tolerant species under salt stress. Proline levels increased in response to salt treatment. However, it contributed only by 0.3‒2.0% to the total osmolyte concentration in the three halophytes (at 400mM NaCl) and even less (0.04%) in the glycophyte, A. thaliana (at 100mM NaCl). Soluble sugars in all three halophytes and free amino acids pool in S. parvula decreased under salt treatment in contrast to the glycophyte, A. thaliana. The contribution of organic osmolytes to the total osmolyte pool increased by salt treatment in the roots, while decreased in halophyte and glycophyte, A. thaliana leaves. Interestingly, this reduction was compensated by a higher relative contribution of K in the leaves of the halophytes, but of Na in A. thaliana. Taken together, biomass data and biochemical indicators show that S. parvula is more salt tolerant than the two Lepidium species. Our data indicate that L. latifolium, as a perennial halophyte with a large biomass, is highly suitable for both restoration of saline habitats and saline agriculture.

Identification of genes regulating traits targeted for domestication of field cress (Lepidium campestre) as a biennial and perennial oilseed crop

BackgroundThe changing climate and the desire to use renewable oil sources necessitate the development of new oilseed crops. Field cress (Lepidium campestre) is a species in the Brassicaceae family that has been targeted for domestication not only as an oilseed crop that produces seeds with a desirable industrial oil quality but also as a cover/catch crop that provides valuable ecosystem services. Lepidium is closely related to Arabidopsis and display significant proportions of syntenic regions in their genomes. Arabidopsis genes are among the most characterized genes in the plant kingdom and, hence, comparative genomics of Lepidium-Arabidopsis would facilitate the identification of Lepidium candidate genes regulating various desirable traits.ResultsHomologues of 30 genes known to regulate vernalization, flowering time, pod shattering, oil content and quality in Arabidopsis were identified and partially characterized in Lepidium. Alignments of sequences representing field cress and two of its closely related perennial relatives: L. heterophyllum and L. hirtum revealed 243 polymorphic sites across the partial sequences of the 30 genes, of which 95 were within the predicted coding regions and 40 led to a change in amino acids of the target proteins. Within field cress, 34 polymorphic sites including nine non-synonymous substitutions were identified. The phylogenetic analysis of the data revealed that field cress is more closely related to L. heterophyllum than to L. hirtum.ConclusionsThere is significant variation within and among Lepidium species within partial sequences of the 30 genes known to regulate traits targeted in the present study. The variation within these genes are potentially useful to speed-up the process of domesticating field cress as future oil crop. The phylogenetic relationship between the Lepidium species revealed in this study does not only shed some light on Lepidium genome evolution but also provides important information to develop efficient schemes for interspecific hybridization between different Lepidium species as part of the domestication efforts.

On the Embryology of Two Species of Genus Lepidium (Brassicaceae)

Some species of genus Lepidium of the family Brassicaceae are ruderal plants, and they can grow well on less fertile soils and may have potential as oilseed crops for marginal lands. To develop cultivation techniques for wild species, the reproductive capacity of the species needs to be revealed. The objective of this work was embryological study of two Lepidium species (L. campestre and L. ruderale). As a result of the study, the main features of male and female generative spheres were established. Male generative sphere: The anther is tetrasporangiate and its wall, the development of which follows the monocotyledonous-type, consists of epidermis, endothecium, one middle layer, and glandular tapetum. Predominantly, tetrahedral microspore tetrads form after simultaneous type of microsporogenesis. The mature pollen grains are two-celled. Female generative sphere: The mature ovule is ana-amphytropous, crassinucellate, and bitegmic with unicellular archesporium that functions as a megaspore mother cell without cutting off of parietal cells. The development of the embryo sac follows the polygonum-type development. The embryo and endosperm develop after the onagrad-type embryogenesis. The established peculiarities of the reproductive biology characterize the studied species as sexually reproducing taxa that guarantee the stability of size of their populations. This is important for the conservation of these species as part of the Bulgarian flora biodiversity given their status of valuable medicinal plants. The data obtained will contribute to the knowledge of the embryological characteristic of genus Lepidium. The results contribute to the understanding of Lepidium biology and potential development of Lepidium species as oilseed cash crops for marginal lands.