Gamete sex and elevation affect genetically based variation for unreduced gamete production in a mixed-ploidy plant

PREMISE

Unreduced gametes are the primary mechanism of neopolyploid formation. Their production in diploid populations is arguably maladaptive, but the magnitude and patterns of genetically based variation maintained in natural populations are poorly understood.

METHODS

We examined variation in male and female unreduced gamete production among plants from different elevations in fireweed, Chamerion angustifolium, grown in a common environment. Using seeds from three high-elevation and three low-elevation diploid populations in one study, and a single diploid population in another, we estimated realized rates of unreduced male (sperm) and female (egg) gamete production by reciprocally pollinating diploid and tetraploid plants and estimating the incidence of tetraploid seeds using flow cytometry.

RESULTS

Unreduced gamete frequencies per plant were similar in the two studies (0.12% vs. 0.08%). High-elevation populations had a greater percentage of fruit with seeds from unreduced gametes, but a lower percentage of seeds per fruit than low-elevation populations. Female unreduced gamete frequencies differed among elevations, but male frequencies did not, and the gamete sexes were not correlated at the plant level.

CONCLUSIONS

We conclude that genetically based variation for unreduced gametes is maintained within and among natural populations, despite their fitness disadvantages, suggesting that local selection may be ineffective at purging them under some conditions.

Antibacterial and Antimycotic Activity of Epilobium angustifolium L. Extracts: A Review

The aim of this work was to provide an overview of available information on the antibacterial and antifungal properties of Epilobium angustifolium extracts. A literature search of Scopus, PubMed/Medline, and Google Scholar for peer-reviewed articles published between January 2000 and June 2023 was undertaken. A total of 23 studies were eligible for inclusion in this review. Significant variation of antimicrobial activity depending on the tested species and strains, type of extract solvent, or plant organs utilized for the extract preparation was found. E. angustifolium extracts were active against both Gram-positive and Gram-negative bacteria and showed antimycotic effects against the fungi of Microsporum canis and Trichophyton tonsurans and the dermatophytes Arthroderma spp. Greater susceptibility of Gram-positive than Gram-negative bacteria to fireweed extracts was found. A strong antibacterial effect was recorded for Staphylococcus aureus, Bacillus cereus, Micrococcus luteus, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii including multi-drug resistant strains. E. angustifolium extract might find practical application as an antimicrobial in wound healing, components of cosmetic products for human and animals, or as food preservatives.

Chemical Management of Senecio madagascariensis (Fireweed)

Fireweed (Senecio madagascariensis Poir.) is a herbaceous weed-producing pyrrolizidine alkaloid that is poisonous to livestock. To investigate the efficacy of chemical management on fireweed and its soil seed bank density, a field experiment was conducted in Beechmont, Queensland, in 2018 within a pasture community. A total of four herbicides (bromoxynil, fluroxypyr/aminopyralid, metsulfuron-methyl and triclopyr/picloram/aminopyralid) were applied either singularly or repeated after 3 months to a mix-aged population of fireweed. The initial fireweed plant density at the field site was high (10 to 18 plants m^-2). However, after the first herbicide application, the fireweed plant density declined significantly (to ca. 0 to 4 plants m^-2), with further reductions following the second treatment. Prior to herbicide application, fireweed seeds in both the upper (0 to 2 cm) and lower (2 to 10 cm) soil seed bank layers averaged 8804 and 3593 seeds m^-2, respectively. Post-herbicide application, the seed density was significantly reduced in both the upper (970 seeds m^-2) and lower (689 seeds m^-2) seed bank layers. Based on the prevailing environmental conditions and nil grazing strategy of the current study, a single application of either fluroxypyr/aminopyralid, metsulfuron-methyl or triclopyr/picloram/aminopyralid would be sufficient to achieve effective control, whilst a second follow-up application is required with bromoxynil.

Isolation, Chemical Characterization and Antioxidant Activity of Pectic Polysaccharides of Fireweed (Epilobium angustifolium L.)

The aim of this study was to isolate pectins with antioxidant activity from the leaves of Epilobium angustifolium L. Two pectins, EA-4.0 and EA-0.8, with galacturonic acid contents of 88 and 91% were isolated from the leaves of E. angustifolium L. by the treatment of plant raw materials with aqueous hydrochloric acid at pH 4.0 and 0.8, respectively. EA-4.0 and EA-0.8 were found to scavenge the DPPH radical in a concentration-dependent manner at 17–133 μg/mL, whereas commercial apple pectin scavenged at 0.5–2 mg/mL. The antioxidant activity of EA-4.0 was the highest and exceeded the activity of EA-0.8 and a commercial apple pectin by 2 and 39 times (IC₅₀—0.050, 0.109 and 1.961 mg/mL), respectively. Pectins EA-4.0 and EA-0.8 were found to possess superoxide radical scavenging activity, with IC₅₀s equal to 0.27 and 0.97 mg/mL, respectively. Correlation analysis of the composition and activity of 32 polysaccharide fractions obtained by enzyme hydrolysis and anionic exchange chromatography revealed that the antioxidant capacity of fireweed pectins is mainly due to phenolics and is partially associated with xylogalacturonan chains. The data obtained demonstrate that pectic polysaccharides appeared to be bioactive components of fireweed leaves with high antioxidant activity, which depend on pH at their extraction.

Epilobium angustifolium L. Essential Oil-Biological Activity and Enhancement of the Skin Penetration of Drugs-In Vitro Study

Epilobium angustifolium L. is a popular medicinal plant found in many regions of the world. This plant contains small amounts of essential oil whose composition and properties have not been extensively investigated. There are few reports in the literature on the antioxidant and antifungal properties of this essential oil and the possibility of applying it as a potential promoter of the skin penetration of drugs. The essential oil was obtained by distillation using a Clavenger type apparatus. The chemical composition was analyzed by the GC-MS method. The major active compounds of E. angustifolium L. essential oil (EOEa) were terpenes, including α-caryophyllene oxide, eucalyptol, β-linalool, camphor, (S)-carvone, and β-caryophyllene. The analyzed essential oil was also characterized by antioxidant activity amounting to 78% RSA (Radical Scavenging Activity). Antifungal activity against the strains Aspergillus niger, A. ochraceus, A. parasiticum, and Penicillium cyclopium was also determined. The largest inhibition zone was observed for strains from the Aspergillus group. The EOEa enhanced the percutaneous penetration of ibuprofen and lidocaine. After a 24 h test, the content of terpene in the skin and the acceptor fluid was examined. It has been shown that the main compounds contained in the essential oil do not penetrate through the skin, but accumulate in it. Additionally, FTIR-ATR analysis showed a disturbance of the stratum corneum (SC) lipids caused by the essential oil application. Due to its rich composition and high biological activity, EOEa may be a potential candidate to be applied, for example, in the pharmaceutical or cosmetic industries. Moreover, due to the reaction of the essential oil components with SC lipids, the EOEa could be an effective permeation enhancer of topically applied hydrophilic and lipophilic drugs.

The Orphan Crop Crassocephalum crepidioides Accumulates the Pyrrolizidine Alkaloid Jacobine in Response to Nitrogen Starvation

Crassocephalum crepidioides is an African orphan crop that is used as a leafy vegetable and medicinal plant. Although it is of high regional importance in Sub-Saharan Africa, the plant is still mainly collected from the wild and therefore efforts are made to promote its domestication. However, in addition to beneficial properties, there was first evidence that C. crepidioides can accumulate the highly toxic pyrrolizidine alkaloid (PA) jacobine and here it was investigated, how jacobine production is controlled. Using ecotypes from Africa and Asia that were characterized in terms of their PA profiles, it is shown that the tetraploid C. crepidioides forms jacobine, an ability that its diploid close relative Crassocephalum rubens appears to lack. Evidence is provided that nitrogen (N) deficiency strongly increases jacobine in the leaves of C. crepidioides, that this capacity depends more strongly on the shoot than the root system, and that homospermidine synthase (HSS) activity is not rate-limiting for this reaction. A characterization of HSS gene representation and transcription showed that C. crepidioides and C. rubens possess two functional versions, one of which is conserved, that the HSS transcript is mainly present in roots and that its abundance is not controlled by N deficiency. In summary, this work improves our understanding of how environmental cues impact PA biosynthesis in plants and provides a basis for the development of PA-free C. crepidioides cultivars, which will aid its domestication and safe use.

Epilobium angustifolium L. Extracts as Valuable Ingredients in Cosmetic and Dermatological Products

Epilobium angustifolium L. is a popular and well-known medicinal plant. In this study, an attempt to evaluate the possibility of using this plant in preparations for the care and treatment of skin diseases was made. The antioxidant, antiaging and anti-inflammatory properties of ethanolic extracts from Epilobium angustifolium (FEE) were assessed. Qualitative and quantitative evaluation of extracts chemically composition was performed by gas chromatography with mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC). The total polyphenol content (TPC) of biologically active compounds, such as the total content of polyphenols (TPC), flavonoids (TFC), and assimilation pigments, as well as selected phenolic acids, was assessed. FEE was evaluated for their anti-inflammatory and antiaging properties, achieving 68% inhibition of lipoxygenase activity, 60% of collagenase and 49% of elastase. FEE also showed high antioxidant activity, reaching to 87% of free radical scavenging using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 59% using 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). Additionally, in vitro penetration studies were performed using two vehicles, i.e., a hydrogel and an emulsion containing FEE. These studies showed that the active ingredients contained in FEE penetrate through human skin and accumulate in it. The obtained results indicate that E. angustifolium may be an interesting plant material to be applied as a component of cosmetic and dermatological preparations with antiaging and anti-inflammatory properties.

Effect of Different Durations of Solid-Phase Fermentation for Fireweed (Chamerion angustifolium (L.) Holub) Leaves on the Content of Polyphenols and Antioxidant Activity In Vitro

Fireweed has recently been recognized as a plant with high antioxidant potential and phenolic content. Its leaves can be fermented to prepare an infusion with ideal antioxidant activity. The aim of this study was to investigate and to determine the influence of solid-phase fermentation of different durations on the variation of polyphenols in the leaves of fireweed. Laboratory experiments were conducted in 2017-2018. The leaves of fireweed, naturally growing, were fermented for different periods of time: not fermented (control) and fermented for 24 and 48 h. The evaluation of polyphenols and antioxidant activity in leaves was performed using high- performance liquid chromatography (HPLC). Additionally, principal component analysis was used to characterize differences in bioactive compounds between fireweed samples fermented at different durations. Solid-phase fermented leaves were characterized by higher contents of oenothein B, quercetin and benzoic acid but had lower contents of quercetin-3-O-rutinoside, luteolin and chlorogenic and gallic acids. Antioxidant activity in short- (24 h) and long-term (48 h) fermentation (compared to control) gave the highest level of regression in 2017, but in 2018 the effect was observed only with short-term fermentation and control. In conclusion, solid-phase fermentation can be used to modulate biologically active compounds in fireweed leaves.

Impacts of soil nitrogen and phosphorus levels on cytotype performance of the circumboreal herb Chamerion angustifolium: implications for polyploid establishment

PREMISE

Although polyploidy commonly occurs in angiosperms, not all polyploidization events lead to successful lineages, and environmental conditions could influence cytotype dynamics and polyploid success. Low soil nitrogen and/or phosphorus concentrations often limit ecosystem primary productivity, and changes in these nutrients might differentially favor some cytotypes over others, thereby influencing polyploid establishment.

METHODS

We grew diploid, established tetraploid, and neotetraploid Chamerion angustifolium (fireweed) in a greenhouse under low and high soil nitrogen and phosphorus conditions and different competition treatments and measured plant performance (height, biomass, flower production, and root bud production) and insect damage responses. By comparing neotetraploids to established tetraploids, we were able to examine traits and responses that might directly arise from polyploidization before they are modified by natural selection and/or genetic drift.

RESULTS

We found that (1) neopolyploids were the least likely to survive and flower and experienced the most herbivore damage, regardless of nutrient conditions; (2) both neo- and established tetraploids had greater biomass and root bud production under nutrient-enriched conditions, whereas diploid biomass and root bud production was not significantly affected by nutrients; and (3) intra-cytotype competition more negatively affected diploids and established tetraploids than it did neotetraploids.

CONCLUSIONS

Following polyploidization, biomass and clonal growth might be more immediately affected by environmental nutrient availabilities than plant survival, flowering, and/or responses to herbivory, which could influence competitive dynamics. Specifically, polyploids might have competitive and colonizing advantages over diploids under nutrient-enriched conditions favoring their establishment, although establishment may also depend upon the density and occurrences of other related cytotypes in a population.

Direct vs. indirect effects of whole-genome duplication on prezygotic isolation in Chamerion angustifolium: Implications for rapid speciation

PREMISE OF THE STUDY

The depiction of polyploid speciation as instantaneous implies that strong prezygotic and postzygotic isolation form as a direct result of whole-genome duplication. However, the direct vs. indirect contributions of genome duplication to phenotypic divergence and prezygotic isolation are rarely quantified across multiple reproductive barriers.

METHODS

We compared the phenotypic differences between diploid and both naturally occurring and synthesized tetraploids (neotetraploids) of the plant Chamerion angustifolium. Using this information and additional published values for this species, we compared the magnitude of isolation (ecological, flowering, pollinator, and gametic) between diploids and natural-occurring tetraploids to that between diploids and neotetraploids.

KEY RESULTS

Differences among ploidy cytotypes were observed for eight of 12 vegetative and reproductive traits measured. Neotetraploids resembled diploids but differed from natural tetraploids with respect to four traits, including flowering time and plant height. Diploid-neotetraploid (2x-4xneo) experimental arrays exhibited lower pollinator fidelity to cytotype and seed set compared with 2x-4xnat arrays. Based on these results and published evidence, reproductive isolation between diploids and neotetraploids across all four life stages averaged 0.48 and deviated significantly from that between diploids and natural tetraploids (RI = 0.96).

CONCLUSIONS

Genome duplication causes phenotypic shifts and contributes directly to prezygotic isolation for some barriers (gametic isolation) but cannot account for the cumulative isolation from diploids observed in natural tetraploids. Therefore, conditions for species formation through genome duplication are not necessarily instantaneous and selection to strengthen prezygotic barriers in young polyploids is critical for the establishment of polyploid species in sympatry.

Effect of inbreeding on pollen tube growth in diploid and tetraploid Chamerion angustifolium: Do polyploids mask mutational load in pollen?

PREMISE OF THE STUDY

Deleterious recessive mutations are an important determinant of fitness (mutational load) in the sporophytic phase of plants and a major cause of inbreeding depression; however, their role in gametophyte function is less well documented but may account for variation in pollen tube growth and siring ability, especially between diploid and polyploid plants, which can mask the load.

METHODS

We investigated the role of mutational load in pollen performance using the perennial polyploid Chamerion angustifolium by comparing tube growth of pollen, in styles and in growth medium, from inbred (selfed) and outbred diploids to that of inbred and outbred tetraploids. Pollen from tetraploids is expected to mask deleterious mutations more effectively in the outbred condition but reveal them after inbreeding. In contrast, gametophytes from diploids should express the same genetic load in inbred or outbred plants.

KEY RESULTS

Pollen tube growth measured in growth medium was highest in outbred tetraploids and generally lower in inbred than outbred plants. The effect of selfing was significant in pollen from tetraploids but not diploids. The differential effect of selfing was also evident in the proportion of pollen reaching the base of styles, but the ploidy × pollination interaction was not significant. Selfing also had a negative effect on sporophyte fitness but was greater in diploids than tetraploids.

CONCLUSIONS

Pollen performance is influenced by the expression of mutational load, which is masked in polyploids. This effect may partly explain strong siring success of tetraploids in this species.

Climatic niche differences between diploid and tetraploid cytotypes of Chamerion angustifolium (Onagraceae)

PREMISE OF THE STUDY

Polyploidy-the possession of more than two copies of each chromosome in the nucleus-is common in flowering plants. Polyploid plants can occupy different geographic ranges than their diploid progenitors, but the factors responsible for maintaining these range differences are poorly understood. Polyploidy can have significant physiological consequences, and the present study aims to determine whether previously described physiological differences between cytotypes are correlated with climatic niches and geographic distributions.

METHODS

Prior research indicates that tetraploid plants of Chamerion angustifolium (Onagraceae) are more tolerant of drought and less tolerant of freezing than diploids, which suggests that they should occupy a niche that is warmer and drier than that of diploids. We extracted climate data for 134 populations of C. angustifolium classified as pure diploid, pure tetraploid, or mixed-ploidy. We compared climatic conditions between these population categories and generated ecological niche models to compare their geographic distribution with prior qualitative estimates.

KEY RESULTS

Pure tetraploid populations occupy habitats that are warmer and drier than those of pure diploid populations. Mixed-ploidy populations occur in habitats that are not strictly intermediate between pure diploid and pure tetraploid populations, but are as cold as pure diploid populations and have intermediate soil moisture deficits. Our niche models were similar to previous qualitative estimates of cytotype geographic distribution.

CONCLUSIONS

The correspondence between the physiological tolerances of cytotypes, their climatic niches, and their geographic distributions suggests that physiological traits are at least partially responsible for differences in the realized climatic niches of diploid and tetraploid C. angustifolium.

Cytotype coexistence leads to triploid hybrid production in a diploid-tetraploid contact zone of Chamerion angustifolium (Onagraceae)

PREMISE OF THE STUDY

Polyploids are often geographically segregated from their diploid progenitors, but the extent of sympatry and the consequences for reproductive isolation and coexistence are rarely quantified. •

METHODS

In this study, we document the distribution and co-occurrence of diploid and tetraploid Chamerion angustifolium among 57 populations within the diploid-tetraploid contact zone in the Canadian Rocky Mountains. Rates of hybrid mating in mixed-ploidy populations were inferred from the frequency of triploid offspring in open-pollinated seed families. •

KEY RESULTS

Twenty-three of 57 populations sampled contained a single cytotype; 20 (87%) were tetraploid and three (13%) were diploid. Thirty-four populations (60%) contained multiple ploidies. Diploid and tetraploid plants occurred in all mixed-ploidy populations; triploids occurred in 13 populations and averaged 1.4% of plants per population. The proportion of tetraploids in a population was negatively related to elevation (partial regression: F = 27.2, P <0.0001) and latitude (partial regression: F = 17.4, P < 0.0001). Triploids were detected in seed from all eight mixed-ploidy populations sampled ( = 3.7% of seed per population), comprising 7% of that expected with random mating (G = 2589.2, df = 1, P <0.0001, n = 2628), and were more often produced by diploid maternal parents than tetraploid parents. •

CONCLUSIONS

Our results indicate that tetraploids regularly coexist with diploids in the contact zone and that this coexistence is likely promoted by both strong reproductive isolation and asymmetric intercytotype mating between diploid and tetraploid C. angustifolium.

Genome duplication and the evolution of conspecific pollen precedence

Conspecific pollen precedence can be a strong reproductive barrier between polyploid and diploid species, but the role of genome multiplication in the evolution of this barrier has not been investigated. Here, we examine the direct effect of genome duplication on the evolution of pollen siring success in tetraploid Chamerion angustifolium. To separate the effects of genome duplication from selection after duplication, we compared pollen siring success of synthesized tetraploids (neotetraploids) with that of naturally occurring tetraploids by applying 2x, 4x (neo or established) or 2x + 4x pollen to diploid and tetraploid flowers. Seed set increased in diploids and decreased in both types of tetraploids as the proportion of pollen from diploid plants increased. Based on offspring ploidy from mixed-ploidy pollinations, pollen of the maternal ploidy always sired the majority of offspring but was strongest in established tetraploids and weakest in neotetraploids. Pollen from established tetraploids had significantly higher siring rates than neotetraploids when deposited on diploid (4x(est) = 47.2%, 4x(neo) = 27.1%) and on tetraploid recipients (4x(est) = 91.9%, 4x(neo) = 56.0%). Siring success of established tetraploids exceeded that of neotetraploids despite having similar pollen production per anther and pollen diameter. Our results suggest that, while pollen precedence can arise in association with the duplication event, the strength of polyploid siring success evolves after the duplication event.