New Interpretations about Clonal Architecture for the Sour Pitaya (<i>Stenocereus gummosus</i>, Cactaceae), Arising from Microsatellite Markers of <i>de novo</i>Isolation and Characterization

The use of molecular markers has improved the ecological and evolutionary research in the case of clonal reproduction species, allowing the identification of boundaries among clonal modules (ramets), genetic individuals (genets), and populations. Microsatellite markers were developed for Stenocereus gummosus, a columnar cactus with both sexual and clonal reproduction which is distributed in the Sonoran Desert, Mexico. 454-Pyrosequencing reads were analyzed to detect microsatellite markers. Forty primer pairs were screened to look for polymorphism. Nine loci were genotyped for two S. gummosus localities. Sampling strategy was intended to avoid collecting a genetic individual more than once, considering that clonal architecture for this cactus was previously deduced as clumped. Polymorphic loci exhibited low allele count, ranging from 2 - 7 (mean of 3.78 ± 0.62 SE);mean heterozygosity values were 0.221 and 0.234 HO and 0.408 and 0.306 HE, with FIS of 0.383 and 0.299, for peninsular and continental localities respectively. Unexpectedly, some multilocus genotypes were found repeated within locality, which were assumed as clones since data was evaluated as sufficient (clonal richness R of 0.966 and 0.897). These results were different from those previously reported: the distribution of clones might as well be intermingled, having a minimum ramet dispersion distance of 30 m. This characteristic was also consistent with the recent colonization proposed for this and other arid lands plants. A wider genetic neighborhood, due to clone dispersion might affect diversity indexes while increasing the chance of geitonogamy and mating among relatives. The markers isolation and its population characterization allowed addressing new questions about S. gummosus ecology, clonal reproduction and reproductive biology.

Methodology of the Tetrazolium Test for Evaluating Physiological Quality in Pitaya (<i>Hylocereus undatus</i>) Seeds

The germination test is routinely used for evaluating physiological quality of seeds, but it has not been satisfactory, since it requires relatively long periods to obtain results. In this sense, there is the possibility to resort to vigor tests, although the absence of standardized methodologies has hindered your applicability and reproducibility. The goal of the present study was to establish a methodology for the tetrazolium test that is effective for evaluating physiological quality in pitaya seeds. So, we used five seed batches obtained from mature fruits of pitaya (Hylocereus undatus), harvested in the years of 2008, 2009, 2010, 2011, and 2012. The experimental design was the completely randomized design, with four replicates of 50 seeds. The tetrazolium test was conducted in a 5 × 4 × 3 factorial plot, corresponding to five batches of pitaya seeds (2008, 2009, 2010, 2011, and 2012), four concentrations of the tetrazolium solution (0.075%, 0.1%, 0.5%, and 1.0%) and three immersion periods (2, 3, and 4 h). In addition, the germination test for the seed batches was carried out and the analyzed variables were: percentage of germination (PG), germination speed index (GSI) and mean germination time (MGT). Data were submitted to ANOVA and means were compared by the Scott-Knott test (p ≤ 0.05). Tetrazolium test conducted at a solution concentration of 0.5% and an immersion period of 3 h proved to be efficient for evaluating physiological quality of pitaya seeds, in order to stratify the seed batches into more viability levels compared to the germination test.

Cytotoxic Effect of Methanol Extracts and Partitions of Two Mexican Desert Plants against the Murine Lymphoma L5178Y-R

Pachycereus marginatus (DC.) Britton & Rose and Ibervillea sonorae (S. Watson) Greene have been used in the Mexican traditional medicine for the treatment of various diseases, including cancer. The present study aims to investigate the cytotoxic activity of these plants against a murine lymphoma. Soxhlet extraction of dried and powdered plant material was performed with methanol. Also, a further partitioning of these methanolic extracts with hexane and ethyl acetate was achieved. The in vitro cytotoxic activity against the murine lymphoma L5178Y-R cell line was assessed via the colorimetric MTT assay. The methanol extract from P. marginatus exhibited high cytotoxic activity (up to 94%) at concentrations ranging from 3.9 to 500 μg/mL;however, hexane and ethyl acetate partitions from this methanolic extract showed lower but significant (p < 0.05) concentration-dependent cytotoxicity (hexane partition up to 94% at 500 μg/mL;ethyl acetate partition up to 94% at 65.5 μg/mL). The methanolic extract and partitions derived from I. sonorae also showed significant (p < 0.05) and concentration-dependent cytotoxicity against L5178Y-R cells at concentrations ranging from 7.81 to 500 μg/mL (methanolic extract up to 63% at 500 μg/mL;hexane partition up to 76% at 250 μg/mL;ethyl acetate partition up to 73% at 500 μg/mL). These results demonstrate that the methanol extracts and partitions from P. marginatus and I. sonorae possess significant cytotoxic activity against the murine lymphoma L5178Y-R and validate the ethnobotanical use of these plants for the treatment of diseases consistent with cancer symptomatology. Previous scientific reports describe the isolation of isoquinoline alkaloids of P. marginatus as well as cucurbitacins from I. sonorae, phytochemicals that could be responsible for their observed cytotoxic activity in this research. The direct extraction with methanol of medicinal plants allows extracting of both high and low-polarity compounds, contrary to the simple extraction with water that only allows obtaining compounds of high polarity. The subsequent partition of the methanol extract with a solvent of low polarity (hexane) and another of medium polarity (ethyl acetate) allows making a preliminary fractionation of the bioactive molecules present in the plant that will facilitate the bioguided chromatographic isolation of the pure compounds responsible for the biological activity of the plant.

Floristic Composition and Community Structure of Epiphytic Angiosperms in an Urban Forest Fragment in the Eastern Amazon

Vascular epiphytes are one of the most important forest components,contributing to microclimatic maintenance.These plants find ideal conditions for development in the Amazon due to the spatial heterogeneity and high temperature and humidity typical of this biome.In recent years,the Brazilian Amazon has undergone dramatic changes in its landscape,mainly due to the increase in deforestation and fire rates.We present here the floristic composition and analyze the community structure of epiphytic angiosperms of an urban forest fragment in Eastern Amazon.A total of 71 epiphytic individuals were recorded belonging to eight species and four families.Orchidaceae was the most representative family,corroborating the pattern for surveys of epiphytic diversity in the Neotropical region.Epiphytic species were found on 24 individuals of 10 tree species.The epiphytic importance value(IVe)was low for all species,except for Aechmea tocantina and Rhipsalis baccifera.Cactaceae was the family with the highest IVe.Most epiphytes were found in the crown of trees(83.1%).The diversity index of the fragment was H’=1.80 and the equity index was J=0.87,reflecting the absence of highly dominant species.Conservation of urban forest fragments is necessary for the maintenance of epiphytic flora and ecosystem services.

Effect of light on seed germination and seedling shape of succulent species from mexico

Aims Light requirements for cactus seed germination have been considered to be associated with their adult plant height and seed mass,but this has not been thoroughly studied for other succulent species.In order to understand seed photosensitivity from desert species belonging to Asparagaceae(subfamily Agavoideae)and Cactaceae,we performed a germination experiment with and without light for 12 species and 2 varieties from 1 species from the Southern Chihuahuan Desert.We also determined if adult growth is totally determined by seedling‘growth form’in cacti.Methods We performed a germination experiment using light and darkness for 13 species from Southern Chihuahuan Desert:10 rosette species(Asparagaceae),as well as 1 globose,1 columnar and 2 varieties from 1 depressed-globose species(Cactaceae).The response variables were seed germination percentage and relative light germination(RLG).In addition,in order to determine if adult-globose cacti could have cylindrical seedlings,we calculated the shape index(height/width ratio)for Coryphanta clavata and Mammillaria compressa.Important Findings All species were considered neutral photoblastic.Eleven species had similar seed germination in both light and dark conditions,and three taxa(M.compressa and the two varieties of Ferocactus latispinus)showed higher germination with light than without it.Agave salmiana,M.compressa and the two varieties of F.latispinus had higher RLG than the other species.Seed mass was an important factor because with higher seed mass there was lower dependence to light.These findings support the hypothesis that small seed mass and light requirements have coevolved as an adaptation to ensure germination.One adult-globose cactus species,M.compressa,and one adult-columnar species,C.clavata,had small seeds and neutral fotoblasticism.Seedlings from these two species exposed to light were cylindrical and those under darkness conditions were columnar.Perhaps seeds from this species are able to germinate in the dark because they produce columnar seedlings with the ability to emerge from greater soil depths where sunlight cannot penetrate.