Brazilian Journal of Botany

The identification and delimitation of bryophyte species are complicated tasks because they are very small plants with limited, and often variable, morphological characters. Molecular data have been useful for clarifying the evolutionary relationships among taxa and the diversity of species. The first classification of mosses using DNA was proposed in 2000, while in Brazil the first phylogenetic study of bryophytes using DNA was published in 2006. Other phylogenetic works involving molecular data have since been published for Dicranaceae, Leucobryaceae, Pylaisiadelphaceae and Sematophyllaceae. Another molecular method, DNA barcoding, has recently begun to be used with Brazilian bryophytes. DNA barcoding consists of identifying a short sequence of DNA from a standardized region of the genome that aids in species identification. Many regions of chloroplast and nuclear DNA are being tested as DNA barcode markers for the identification of various groups of plants. The selection of such markers for bryophytes has been controversial and is yet to be investigated for Brazilian taxa. The project “DNA—barcoding of Brazilian bryophytes—a case study to improve the identification of tropical bryophyte species” started in 2014 with an initial investigation of four bryophyte genera, including three mosses and one liverwort. Studies that include molecular tools are important because they contribute to biodiversity assessment, forensic analyses and studies of life history and ecology, among other areas of knowledge.

Conchocarpus is the largest genus in the subtribe Galipeinae, tribe Galipeeae, distributed from Nicaragua to northern Bolivia and southern Brazil, with the center of species diversity in the Brazilian Atlantic Rainforest. Five species were recently segregated to a new genus (Dryades), thereby restoring the monophyly of Conchocarpus sensu stricto. In addition to the wide morphological diversity of Conchocarpus species, to date, few chemical aspects have been explored, mainly in regard to wax composition. This study aims to compare the chemical composition of the cuticular wax of selected species of Conchocarpus sensu stricto and Dryades, in order to determine their similarities and/or differences, as well as discuss possible correlations with habitats, and potential taxonomic implications. The main results showed that in general, Conchocarpus and Dryades could be distinguished, with species of the former genus exhibiting longer-chain alkanes and those of the latter higher triterpene diversity. Moreover, species inhabiting the Atlantic Rainforest have a thinner wax load, reduced amounts of triterpenes and are rich in alkanes, while those from “Restinga” vegetation exhibit a higher wax content, fewer alkanes, and large amounts of triterpenes.

Some species of non-cultivated passion fruit plant have important contributions to genetic improvement. However, there are few studies concerning about embryogenic and organogenic calli mainly related with structural alterations during their development. The objective of this work was to characterize, structurally the callogenesis on leaf explants of Passiflora gibertii N. E. Brown. The cotyledons were inoculated in MS culture medium, containing half salt concentration, supplemented with sucrose (3 %), and picloram+kinetin for the calli formation. Different calli colors were obtained and used for structural analyses. The calli colors were translucent, white, dark-yellow, white-brown, light-yellow, and white-yellow. After 30 days of cultivation, the calli were fixed in Karnovsky and prepared for the visualization under the scanning and transmission electron microscope and optic microscope. Translucent and light-yellow calli did not present morphogenic characteristics. The cells had different shapes forming non-organized cellular system and the absence or reduced starch content. On the other hand, white and dark-yellow calli manifested embryogenic characteristics such as small isodiametric cells, an organized cellular, dense cytoplasm rich in mitochondria and endoplasmic reticulum, small vacuole and significant starch contend. The culture medium supplemented with 4.14 μM of picloram +0.46 μM of kinetin is the most suitable to induce embryogenic cells.

(Anthocyanins and tannins: is the urban air pollution an elicitor factor?) In order to survive in highly adverse conditions, plants have evolved a genetic capacity for compensating drastic environmental changes, by producing antioxidants that neutralize the effects of stress, such as those caused by oxidant pollutants. One example is Psidium guajava cv. Paluma (guava), which is described as an efficient bio-indicator of tropospheric ozone, by displaying typical foliar injury, characterized by reddening on the adaxial surface. The aim of this study was to investigate alterations in phenolic compounds content (anthocyanins and tannins) in P. guajava on a field condition of atmospheric pollutants at São Paulo city. Four field exposure assays were performed to investigate the alterations on phenolic contents under pollution stress and under seasonal variations. Principal components and regression analysis indicated that the concentrations of ozone and phenolic compounds accumulation can be highly correlated. Accumulated precipitation during the field exposures showed significant correlations with tannin contents. Contents of foliar proanthocyanidins were correlated to precipitation, global solar radiation, and leaf injury. On a field condition, many factors can elicit response on phenolic contents, e.g., presence of other pollutants, climatic conditions, and biotic factors. Urban air pollution seems to be an elicitor factor to the production of phenolic compounds on P. guajava, specially anthocyanins and tannins, but the weather conditions are crucial to determine this pollution influence.

Peucedanum praeruptorum Dunn is a well-known Chinese medicinal plant that mainly contains coumarins derived from the phenylpropanoid pathway. Phenylalanine ammonia-lyase (PAL) is the first key enzyme in the phenylpropanoid pathway and catalyzes the formation of trans-cinnamic acid (t-CA) by L-phenylalanine (L-Phe). Two PALs (PpPAL1 and PpPAL2) were cloned and verified in this study, demonstrating that there is a multi-gene family of PAL in P. praeruptorum. PpPAL1 (GenBank accession number: MZ355581) and PpPAL2 (GenBank accession number: MZ355582) contained open reading frame of 2157 bp encoding 718 amino acids and 2118 bp encoding 705 amino acids, respectively. BLAST analysis showed that the amino acid sequences of two novel PpPALs were highly similar to other known plant PAL proteins. To confirm their functions, the two PpPALs were cloned into the pET-30a vector and expressed in Escherichia coli Transetta (DE3). The enzymatic activity of the two PAL recombinant proteins was subsequently detected. They both catalyzed the conversion of L-Phe to t-CA, but the activity of PpPAL2 was higher than that of PpPAL1. Phylogenetic results revealed that PpPAL1 and PpPAL2 were classified into different clusters. In addition, tissue-specific expression of the two PpPALs was different of both non-bolting and bolting plants. These results might be useful for future studies regarding phenylpropanoid biosynthesis and improving the content of medicinal components in P. praeruptorum.

Cross-amplification and transferability of ten microsatellite loci previously developed for Masdevallia solomonii Luer & R.Vasquéz were assessed in M. chaparensis T. Hashim, M. exquisita Luer & Hirtz, M. scandens Rolfe and M. yungasensis Hashimoto. The transferability rates and a phylogenetic analysis are presented here to show potential application for these markers. Cross-amplification was fully successful (100 %) in closely related species (M. yungasensis and M. chaparensis) and highly successful in M. exquisita and M. scandens (90 %). Average allele number/effective allele was 9.3/6.0 in M. chaparensis, 9.4/5.7 in M. exquisita, 5.8/3.2 in M. scandens and 6.2/3.9 in M. yungasensis. Deviations from Hardy–Weinberg equilibrium were observed in seven loci in M. chaparensis, five loci in M. exquisita, one locus in M. scandens, and two loci in M. yungasensis. The high transferability rates obtained indicate high potential for comparative population genetic studies in these species of great interest for conservation.

Gene expression has been extensively studied in plant science research, mainly for the assessment of plant stress responses. Real-time-quantitative polymerase chain reaction (RT-qPCR) is an important tool for obtaining this information because it is a quick and easy technique to acquire a large amount of molecular data for both model and non-model plants. For a successful RT-qPCR analysis, gene expression should be carefully normalised. Genes involved in essential biological processes that exhibit constitutive expression are commonly selected as internal standards to normalise RT-qPCR experiments. In this study, the transcription profiles of 13 candidate reference genes for RT-qPCR were evaluated in three guarana cultivars (BRS-Amazonas, BRS-Maués and BRS-Luzéia) using different tissues (vegetative and fruit) in varying developmental stages. Two different algorithms, NormFinder and GeNorm, were utilised to assess gene stability. In general, the two algorithms did not select the same pairs of genes for all analysed conditions. For the largest group (the fruits of all cultivars), NormFinder selected the pair EF1A/UBQ, whereas GeNorm chose ACT/GAPDH as the best normalising genes. Thus, we recommend the use of at least four reference genes for the normalisation of gene expression in guarana plant studies.

The legume Mimosa tenuiflora (Wild) Poir occurs in the “Caatinga” and is used as a popular remedy because of its medicinal properties related to the presence of secondary compounds in several parts of the plant. The arbuscular mycorrhizal fungi (AMF) are associated with most legumes, including M. tenuiflora, benefiting the growing process and the production of secondary compounds; however, the production of phytochemicals in response to AMF inoculation has not been defined yet. The aim of this study was to evaluate the influence of AMF on the production of phenolic compounds in the aerial part of M. tenuiflora. We analyzed the following parameters: height, stem diameter, number of leaves, fresh matter from the aerial part, dry matter from the aerial part, mycorrhizal colonization, soluble carbohydrates, total proteins, total phenols, total flavonoids, and total tannins. The mycorrhizal association did not benefit the growing process and/or the production of secondary compounds, demonstrating that mycorrhizal technology is not always an alternative to increase the production of plant secondary metabolism molecules. This study is the first report on the results of the inefficiency of mycorrhizal symbiosis regarding the optimization of phenolic compounds in plants of the “Caatinga”.

Sub-Antarctic macroalgae can be a feasible source of innumerous bioactive compounds that can display important biological activities. In this sense, the aims of this work were to evaluate the chemical composition, antimicrobial activity and cytotoxic potential of n-hexane extracts from sub-Antarctic seaweed Mazzaella laminarioides (Bory) Fredericq at distinct development phases. Results showed that extracts were constituted of as much as 65 distinct compounds that could be distributed mainly among hydrocarbons, fatty acids, sterols and fatty alcohols. Generally, there were significant differences (P < 0.05) in the concentrations of compounds comparing distinct development phases. Antimicrobial evaluation indicated that n-hexane extracts of cystocarpic and tetrasporophytic phase of M. laminarioides inhibited the growth of most organisms tested, reaching minimum inhibitory concentrations of 0.0312 mg mL−1 against Enterococcus faecalis (Andrewes and Horder) and 0.25 mg mL−1 against Acinetobacter baumannii (Bouvet and Grimont). Cytotoxic evaluation of extracts showed no toxicity to normal cells at concentrations below 1 mg mL−1. Therefore, M. laminarioides from the sub-Antarctic region had antimicrobial potential that could be explored on further commercial applications.