New findings on the pollination biology of Mauritia flexuosa (Arecaceae) in Roraima, Brazil: linking dioecy, wind, and habitat

Pollination Ecology, Breeding System, and Conservation of Butia lallemantii Deble & Marchiori (Arecaceae): A Useful Dwarf Palm Tree from the Pampa

The Dwarf Palm, Butia lallemantii Deble & Marchiori, is an endangered species endemic to the Pampa biome and typically grows in sandy and rocky soils. Given its economic, ecological, and cultural relevance, it is crucial to understand the ecology and biology of this species to encourage its preservation and highlight its significance for the Pampa. This study aims to investigate whether this palm relies on animal vectors for pollination, analyze its breeding system, and propose strategies for its conservation and sustainable use. We conducted field observations on pollination ecology, identified floral visitors, and designed six breeding system experiments to test cross-compatibility, self-compatibility, and apomixis. Additionally, we conducted a literature review to propose conservation strategies. Butia lallemantii is pollinator-dependent and self-compatible. The flowers are mostly melittophilous and offer pollen and nectar for floral visitors. The main pollinators are native Meliponinae and Halictinae bees and the introduced Apis mellifera. This study represents the first comprehensive and complete examination of the breeding system and pollination process on Butia palms. This palm can provide materials for industries, but urgent actions are needed to preserve the remaining populations through effective policies and strategies. Furthermore, this palm should be integrated into diversified agroecosystems to evaluate its adaptability to cultivation.

Melissopalynological Analysis of Honey from French Guiana

Beekeeping directly depends on the floral biodiversity available to honey bees. In tropical regions, where nectar and pollen resources are numerous, the botanical origin of some honey is still under discussion. A precise knowledge of plants foraged by honey bees is useful to understand and certify the botanical origin of honey. In this study, attention was paid to honey samples from the French Guiana Atlantic coast where beekeepers generally place their hives in four types of biotopes: seaside vegetation, mangrove, savannah, and secondary forest. Pollen analysis of 87 honey samples enabled the identification of major plants visited by Africanized honey bees during the dry season (approximately from July to January). Through melissopalynologic analysis, 51 pollen types were identified and classified according to their relative presence. Frequently observed pollens (with relative presence > 50%) in French Guiana kinds of honey were those from Mimosa pudica, Cocos sp., Rhyncospora sp., Avicennia germinans, Paspalum sp., Spermacoce verticillata, Tapirira guianensis, Cecropia sp., Myrtaceae sp., Mauritia flexuosa sp., Solanum sp., and Protium sp. In many honeys, only M. pudica was over-represented (relative frequency > 90%). Color and electrical conductivity in French Guiana honeys exhibit significant variations, with color ranging from 27 mm to 110 mm Pfund, and electrical conductivity ranging from 0.35 to 1.22 mS/cm.

Life is in the air: An expedition into the Amazonian atmosphere

Biological particles suspended in the atmosphere have a crucial role in the dynamics of the biosphere underneath. Although much attention is paid for the chemical and physical properties of these particles, their biological taxonomic identity, which is relevant for ecological research, remains little studied. We took air samples at 300 meters above the forest in central Amazonia, in seven periods of 7 days, and used high-throughput DNA sequencing techniques to taxonomically identify airborne fungal and plant material. The use of a molecular identification technique improved taxonomic resolution when compared to morphological identification. This first appraisal of airborne diversity showed that fungal composition was strikingly different from what has been recorded in anthropogenic regions. For instance, basidiospores reached 30% of the OTUs instead of 3–5% as found in the literature; and the orders Capnodiales and Eurotiales—to which many allergenic fungi and crop pathogens belong—were much less frequently recorded than Pleosporales, Polyporales, and Agaricales. Plant OTUs corresponded mainly to Amazonian taxa frequently present in pollen records such as the genera Helicostilys and Cecropia and/or very abundant in the region such as Pourouma and Pouteria. The origin of extra-Amazonian plant material is unknown, but they belong to genera of predominantly wind-pollinated angiosperm families such as Poaceae and Betulaceae. Finally, the detection of two bryophyte genera feeds the debate about the role of long distance dispersal in the distribution of these plants.

Selective Sweeps Lead to Evolutionary Success in an Amazonian Hyperdominant Palm

Despite the global importance of tropical ecosystems, few studies have identified how natural selection has shaped their megadiversity. Here, we test for the role of adaptation in the evolutionary success of the widespread, highly abundant Neotropical palm Mauritia flexuosa. We used a genome scan framework, sampling 16,262 single-nucleotide polymorphisms (SNPs) with target sequence capture in 264 individuals from 22 populations in rainforest and savanna ecosystems. We identified outlier loci as well as signal of adaptation using Bayesian correlations of allele frequency with environmental variables and detected both selective sweeps and genetic hitchhiking events. Functional annotation of SNPs with selection footprints identified loci affecting genes related to adaptation to environmental stress, plant development, and primary metabolic processes. The strong differences in climatic and soil variables between ecosystems matched the high differentiation and low admixture in population Bayesian clustering. Further, we found only small differences in allele frequency distribution in loci putatively under selection among widespread populations from different ecosystems, with fixation of a single allele in most populations. Taken together, our results indicate that adaptive selective sweeps related to environmental stress shaped the spatial pattern of genetic diversity in M. flexuosa, leading to high similarity in allele frequency among populations from different ecosystems.

Pathways Related to the Anti-Cancer Effects of Metabolites Derived from Cerrado Biome Native Plants: An Update and Bioinformatics Analysis on Oral Squamous Cell Carcinoma

BACKGROUND

Oral cancer is a significant health problem worldwide. Oral squamous cell carcinoma (OSCC) is a malignant neoplasm of epithelial cells that mostly affects different anatomical sites in the head and neck and derives from the squamous epithelium or displays similar morphological characteristics. Generally, OSCC is often the end stage of several changes in the stratified squamous epithelium, which begin as epithelial dysplasia and progress by breaking the basement membrane and invading adjacent tissues. Several plant-based drugs with potent anti-cancer effects are considered inexpensive treatments with limited side effects for cancer and other diseases.

OBJECTIVE

The aim of this review is to explore whether some Brazilian plant extracts or constituents exhibit anti-tumorigenic activity or have a cytotoxic effect on human oral carcinoma cells.

METHODS

Briefly, OSCC and several metabolites derived from Brazilian plants (i.e., flavonoids, vinblastine, irinotecan, etoposide and paclitaxel) were used as keywords to search the literature on PubMed, GenBank and GeneCards.

RESULTS

The results showed that these five chemical compounds found in Cerrado Biome plants exhibit anti-neoplastic effects. Evaluating the compounds revealed that they play a main role in the regulation of cell proliferation.

CONCLUSION

Preserving and utilising the biodiversity of our planet, especially in unique ecosystems, such as the Cerrado Biome, may prove essential to preserving and promoting human health in modern contexts.

Rivers shape population genetic structure in Mauritia flexuosa (Arecaceae)

The Mauritia flexuosa L.f. palm is known as the "tree of life" given its importance as fundamental food and construction resources for humans. The species is broadly distributed in wet habitats of Amazonia and dry habitats of the Amazon and Orinoco river basins and in the Cerrado savanna. We collected 179 individuals from eight different localities throughout these habitats and used microsatellites to characterize their population structure and patterns of gene flow. Overall, we found high genetic variation, except in one savanna locality. Gene flow between populations is largely congruent with river basins and the direction of water flow within and among them, suggesting their importance for seed dispersal. Further, rivers have had a higher frequency of human settlements than forested sites, contributing to population diversity and structure through increased human use and consumption of M. flexuosa along rivers. Gene flow patterns revealed that migrants are sourced primarily from within the same river basin, such as those from Madeira and Tapajós basins. Our work suggests that rivers and their inhabitants are a critical element of the landscape in Amazonia and have impacted the dispersal and subsequent distribution of tropical palm species, as shown by the patterns of genetic variation in M. flexuosa.

Reproductive biology and pollination ecology of Triplaris gardneriana (Polygonaceae): a case of ambophily in the Brazilian Chaco

Triplaris gardneriana (Polygonaceae) is a dioecious pioneer tree reported as insect-pollinated, despite possessing traits related to anemophily. Here, we analyse the possible roles of insects and wind on the pollination of this species to establish whether the species is ambophilous. We carried out observations of floral biology, as well as on the frequency and behaviour of pollinators visiting flowers in a population of T. gardneriana in the Chaco vegetation of Brazil. We conducted experimental pollinations to determine the maternal fertility of female plants and whether they were pollen-limited, and we also conducted aerobiological experiments to provide evidence of how environmental factors influence atmospheric pollen dispersal. The population comprised an area of approximately 152.000 m² and was composed of 603 female and 426 male plants (sex ratio = 0.59:0.41). We observed 48 species of insects visiting flowers of T. gardneriana, of which the bees Scaptotrigona depilis and Apis mellifera scutellata were the most effective pollinators. We recorded pollen grains dispersed by wind on 74% of the glass slides placed on females, located at different distances (1-10 m) from male plants. Airborne pollen concentration was negatively correlated with relative humidity and positively correlated with temperature. Our observations and experimental results provide the first evidence that T. gardneriana is an ambophilous species, with pollen dispersal resulting from both animal and wind pollination. This mixed pollination strategy may be adaptive in T. gardneriana providing reproductive assurance during colonisation of sites with different biotic and abiotic conditions.

Speaking of food: connecting basic and applied plant science

The Food and Agriculture Organization (FAO) predicts that food production must rise 70% over the next 40 years to meet the demands of a growing population that is expected to reach nine billion by the year 2050. Many facets of basic plant science promoted by the Botanical Society of America are important for agriculture; however, more explicit connections are needed to bridge the gap between basic and applied plant research. This special issue, Speaking of Food: Connecting Basic and Applied Plant Science, was conceived to showcase productive overlaps of basic and applied research to address the challenges posed by feeding billions of people and to stimulate more research, fresh connections, and new paradigms. Contributions to this special issue thus illustrate some interactive areas of study in plant science-historical and modern plant-human interaction, crop and weed origins and evolution, and the effects of natural and artificial selection on crops and their wild relatives. These papers provide examples of how research integrating the basic and applied aspects of plant science benefits the pursuit of knowledge and the translation of that knowledge into actions toward sustainable production of crops and conservation of diversity in a changing climate.

How do habitat and climate variation affect phenology of the Amazonian palm, Mauritia flexuosa?

Although the dioecious palm, Mauritia flexuosa plays a pivotal role in Amazonian ecology and economy, little is known about its flowering and fruiting patterns. We investigated the role of habitat and inter-annual precipitation in the phenology of M. flexuosa. We calculated sex ratios and recorded phenology for 20 mo in four populations (N = 246) of savanna–forest ecotone (two sites) and forest (two sites) habitat in Roraima, Brazilian Amazonia. Sex ratios were significantly female-biased, and >98% of females set fruit. No significant relationship was found between habitat and sex. Flowering occurred at the wet/dry season interface (August–November), and fruit maturation occurred during the wet season (May–August). Males and females flowered synchronously, and neither the onset nor termination of flowering differed significantly between habitats. Flowering was negatively associated with present precipitation and positively correlated with prior precipitation (3 mo). Fruiting was positively associated with present precipitation and unrelated to prior precipitation (3 mo). We conclude that habitat has an insignificant effect, although short-term climatic variation may influence phenology of this species in northern Amazonia. These results highlight the need for long-term studies relating flowering and fruiting events, and inter-annual climatic variation.