Effects of fluoride emission on the morphoanatomy of three plant species endemics to Brazil using passive biomonitoring

Fluoride is the most phytotoxic atmospheric pollutant. The objective of this study was to evaluate the effects of fluoride emissions by an aluminum smelter on three plant species endemics to Brazil, located at Parque Estadual do Itacolomi (PEI). The monitored species were Byrsonima variabilis (Malpighiaceae), Myrceugenia alpigena (Myrtaceae), and Eremanthus erythropappus (Asteraceae), which were monitored during 9 months using passive biomonitoring at five different locations with different distances from the smelter. The monitored species did not show macroscopic phytotoxicity damage to fluoride; however, they did show microscopic damage. The species closer to the smelter presented more severe anatomic damages, such as rupture of cell walls, protoplast retraction, and trichome alterations. Damaged stomatal ledges, flaking epicuticular wax, and damages to trichomes were observed. M. alpigena showed a higher accumulation of fluoride than the other species at all monitored sites. The test for cell death with Evans Blue was positive for the three studied species. Through biomonitoring in the PEI, we concluded that the emissions from the aluminum smelter affect the native vegetation and that due to the greater accumulation of fluoride and the diversity of microscopic damage in M. alpigena, the use of this species in the monitoring of environments polluted by fluoride is enhanced.

Antileishmanial activity of the essential oils of Myrcia ovata Cambess. and Eremanthus erythropappus (DC) McLeisch leads to parasite mitochondrial damage

Leishmania amazonensis is a species causative of cutaneous and anergic diffuse cutaneous leishmaniasis, treatment-resistant form, in the New World. Plants essential oils exhibit great potential as microbicide agents. We described the composition of the essential oils of two plants native from Brazil, Myrcia ovata, with geranial and neral as major constituents, and Eremanthus erythropappus, with α-bisabolol. In vitro effects of these essential oils on L. amazonensis promastigotes growth and ultrastructure were analysed as well as their cytotoxicity to murine macrophages. Both oils were highly active with IC₅₀/96 h of 8.69 and 9.53 µg/mL for M. ovata and E. erythropappus against promastigotes and caused ultrastructural alterations including mitochondrial enlargement. Cytotoxicity for murine macrophages varied with the oil concentrations. The IC₅₀ low values of both M. ovata and E. erythropappus oils against L. amazonensis and their relative low cytotoxicity to mammal host cells support their potential use against cutaneous leishmaniasis.

Development and characterization of nuclear microsatellite markers for Eremanthus erythropappus and their transferability across related species

Background

We developed simple sequence repeats (SSR) for Eremanthus erythropappus (DC.) MacLeish, an endangered tree species endemic to the Brazilian Savanna and Atlantic Forest biomes, and tested their transferability to two closely related Eremanthus species.

Results

Using a genomic library enriched with tandem repeat motifs, we identified 16 primer pairs, and characterized them in two populations. Nine primers amplified the expected size fragments and seven SSRs were polymorphic, providing a total of 38 alleles and an average of 4.22 alleles per marker. The polymorphic information content (PIC) ranged from 0.44 to 0.94 with an average of 0.65. The average observed heterozygosity across all loci varied from 0.61 to 1.00. The observed (H_O) and expected (H_E) heterozygosity within the two populations varied from 0.65 to 1.00 and from 0.31 to 1.00, respectively.

Conclusions

These newly developed SSR markers are a powerful tool for population genetic analyses and may be useful in studies on species ecology, evolution, and taxonomy.

Influence of soil texture on nutrients and potentially hazardous elements in Eremanthus erythropappus

Understanding the factors that control uptake rates and allocation of chemical elements among plant organs is a fundamental prerequisite to improve phytostabilization techniques of hazardous elements in contaminated areas. The present study shows evidence that different substrate textures (coarse and fine laterite) do not significantly change the partitioning of root and shoot dry biomass and with few exceptions, do not significantly affect the final average concentration of elements in Eremanthus erythropappus, but change the root:shoot allocation of both essential nutrients and elements potentially toxic to biota. Growth on coarse laterite resulted in significant higher K (30%), Mg (34%), P (25%), S (32%), Cu (58%), and Na (43%) concentrations in roots and lower Cd concentration (29%). In shoots, coarse laterite led to reduction in K, Fe, Al, and Cr and increase in Na and Sr concentrations. Changes in element allocation could be, in part, a result of differences in the water availability of substrates. Matric potential in coarse laterite was significantly lower in at least 47% of the days analyzed throughout the year. Changes in element phytoextraction or phytostabilization potential could influence the efficiency of rehabilitation projects in areas degraded by mining activities.

Assessing the Chemical Composition and Antimicrobial Activity of Essential Oils from Brazilian Plants-Eremanthus erythropappus (Asteraceae), Plectrantuns barbatus, and P. amboinicus (Lamiaceae)

The chemical composition and antimicrobial activity of essential oils obtained from three Brazilian plant species-leaves and branches of Eremanthus erythropappus (Asteraceae), leaves of Plectranthus barbatus, and leaves of P. amboinicus (Lamiaceae)-were determined. Analysis by GC/MS and determination of Kovats indexes both indicated δ-elemene (leaves-42.61% and branches-23.41%) as well as (-)-α-bisabolol (leaves-24.80% and stem bark-66.16%) as major constituents of E. erythropappus essential oils. The main components of leaves of P. barbatus were identified as (Z)-caryophyllene (17.98%), germacrene D (17.35%), and viridiflorol (14.13%); whereas those of leaves of P. amboinicus were characterized as p-cymene (12.01%), γ-terpinene (14.74%), carvacrol (37.70%), and (Z)-caryophyllene (14.07%). The antimicrobial activity against yeasts and bacteria was assessed in broth microdilution assays to determine the minimum inhibitory concentration (MIC) necessary to inhibit microbial growth. In addition, the crude oil of branches of E. erythropappus was subjected to chromatographic separation procedures to afford purified (-)-α-bisabolol. This compound displayed biological activity against pathogenic yeasts, thus suggesting that the antimicrobial effect observed with crude oils of E. erythropappus leaves and branches may be related to the occurrence of (-)-α-bisabolol as their main component. Our results showed that crude oils of Brazilian plants, specifically E. erythropappus, P. barbatus, and P. amboinicus and its components, could be used as a tool for the developing novel and more efficacious antimicrobial agents.

Growing Eremanthus erythropappus in crushed laterite: A promising alternative to topsoil for bauxite-mine revegetation

Topsoil is the preferred substrate for areas requiring rehabilitation after bauxite mining. However, topsoil is sometimes lacking and so there is a need to test the suitability of other, locally available substrates. In an abandoned bauxite mine in Southeastern Brazil, small patches of native vegetation spontaneously established in shallow depressions over weathered laterite, suggesting that granulometric reduction may have facilitated the establishment of plants. To test this hypothesis, blocks of laterite collected in the area were crushed to simulate texture observed in the vegetation patches. Topsoil collected in a preserved ferruginous field near to the extraction area was also used as a substrate in which Eremanthus erythropappus seedlings, a native woody species, were grown. Seedlings were cultivated without fertilizers in these two substrates and also directly over the exposed and uncrushed laterite. The species proved to be very promising for the revegetation, showing a high survival rate in all substrates. Higher annual growth rates and higher final biomass values were observed in topsoil, but the granulometric reduction of laterite doubled plant growth rate in comparison to the exposed laterite. This result was likely due to the increased availability of essential nutrients to plants and to the improvement in physical conditions for root growth and functioning. Moreover, seedling allometry was not altered by the type of substrate, suggesting that the species was highly tolerant to the new substrate conditions, a fundamental characteristic for success of revegetation of bauxite extraction degraded areas.