Brazilian Journal of Botany最新文献

Light availability and seed dispersal can play a determinant role for plant growth and survival. The intricate interplay among these factors, coupled with pronounced topographic and elevational variation, may influence forest composition and structure. Despite the structural significance of palms within the Atlantic Forest, they are scarcely represented in both inventories and ecological studies. Additionally, functional trait variation among palm species is barely tested, and species are usually categorized into one or two functional types. We examined a palm community in terms of floristic composition and species replacement along an elevation gradient from 0 to 1400 m. Furthermore, we measured a set of morpho-physiological traits strongly associated with growth and survival strategies, such as photosynthetic capacity through Rapid Light Curves, leaf traits, height and fruit size and number. Our findings reveal highest richness from 300 to 800 m. Otherwise, palm density increased along elevation, peaking after 1200 m, mainly associated with E. edulis increase in density along elevation. Additionally, traits associated with enhanced light capture and dispersal capacity, i.e., higher photosynthetic capacity, height, and fruit number, were common among species widely distributed along the entire elevation gradient, such as Euterpe edulis M. and Geonoma schottiana M. In contrast, species with narrower distributions, exhibit the opposite traits. In conclusion, in our study area there is an integral role of light response and dispersal capacity in shaping the palm community structure in the Atlantic Forest along an elevation gradient from 0 to 1400 m.

The main purpose of this work was to confirm the previously proposed model of the laser radiation interaction with the epidermal layer of monocotyledons cells. The other purpose was to show that plant age affects polarization parameters and polarization direction affects plant development. The methods used in this work include the development of LED light sources, the polarization parameters assessment (polarization index), and statistical analysis. The maize plants (Zea mays L.), variety “Early gourmet 121,” optical setup, and software TXP Series Instrumentation were used in the work. Plants were grown under white light at an intensity of 200 µmol m⁻² s⁻¹. The study established that the harmonic ellipticity polarization change by ± 12.0° occurs when the linearly polarized light passed through the maize leaves depending on the axis rotation angle of the epidermal cells. In addition, it was shown that the maize leaves of different ages could have different values of the refractive index anisotropy and, consequently, different polarization ellipticity index. It has been established that the maize leaves with ordered structure of epidermal cells are able to change the polarized radiation ellipticity. That confirms the previously proposed model of the polarized light interaction with plant leaves. We established that linearly polarized light passing through the leaves of maize plants turns into elliptically polarized light, which is able to interact more effectively with the photosensitive protein structures of the leaf inner cells.

Abstract

Citrus sinensis (L.) Osbeck is a valuable plant belonging to the Rutaceae family. Stress is induced in plants by abiotic factors such as drought, salinity, and temperature. The monovalent cation proton antiporter (CPA) superfamily, which includes the K⁺ efflux antiporter (KEA) and Na⁺/H⁺ exchanger (NHX) genes, plays a crucial role in the regulation of physiological events. This study aims to identify the KEA and NHX genes of C. sinensis and elucidate the roles of these genes in the response to abiotic stress. For this purpose, phylogenetic structure, distribution of chromosomes, gene duplications, gene and protein structures, cis-acting elements, functional gene ontologies, targeted miRNAs, and in silico PCR primer searches were performed using CsNHX and CsKEA sequences. Two KEA and fifty-five NHX were identified as a result of the analysis. Nine of the fifty-five genes (CsNHX5, CsNHX11, CsNHX12, CsNHX17, CsNHX27, CsNHX28, CsNHX47,CsNHX48, and CsNHX55) have been identified as playing a role in the stress response. On the phylogenetic tree, NHX genes were observed to be divided into three distinct clusters. The existence of multiple segmental and tandem duplications in the CsNHX genes has been demonstrated. Stress-related motifs were identified in the promoter regions of CsKEA and CsNHX by cis-acting element analysis, while stress-related miRNAs were identified by miRNA analysis. Consequently, KEA genes are responsible for transport, but they may also play a role in abiotic stress, as they contain cis-acting elements involved in the stress response and are targeted by miRNAs associated with stress. In addition, it has been determined that CsNHX5, which plays a role in the stress response, has the potential to be used in future transgenic plant production studies as it satisfies the PCR in silico criteria.

Abstract

Environmental factors and structural characteristics associated with tree communities influence patterns of diversity, and distribution of structurally dependent plants, such as vascular epiphytes. In this study, we investigated the diversity, composition, and structure of vascular epiphytes among five areas of white-sand ecosystems (WSEs or campinaranas), which are considered "islands" of vegetation immersed in other forest matrices, in the Central Amazon, Brazil. We tested the following hypotheses: (1) turnover is the main mechanism that drives beta diversity, (2) the epiphyte communities are geographically structured, with nearby areas sharing a greater number of species, (3) the floristic composition of vascular epiphytes differs between WSE areas and presents typical species in each of them, and (4) the size of the area, the distance from the adjacent forest matrix and the structural characteristics of the tree vegetation influence the composition and distribution of vascular epiphyte communities in the WSE. A total of 17,808 epiphyte individuals were recorded on 486 phorophytes. Our results indicate spatial turnover in the vascular epiphyte composition between WSEs studied. The size of the WSE, the distance from adjacent environments, and structural variables of vegetation (average canopy height and basal area) influence the distribution of vascular epiphytes in the WSEs. In addition, we observed that the communities have geographical structuring, with nearby areas sharing a greater number of taxa among themselves; however, the characteristic species and the epiphytic importance value are different between the areas. Differences in epiphyte communities between areas indicate that each WSe is unique; therefore, the conservation of multiple areas is necessary to preserve the diversity of epiphytes in these ecosystems.

Abstract

A few biotypes (plants possessing abnormal features) of Goswamia costata Zhang and Zhang, partly resembling Ophioglossum rubellum Welw. ex A. Braun, are presented out of which finding of the development of spores on the tropophyll (leaf) of plants is exceedingly important.

Most alarming feature is that the spores on leaves do not resemble spores produced by the sporangia in the sporophore (fertile spike) of the parent plant, a trait only so far described by the senior author more than two decades ago on margins of Ophioglossum eliminatum Khandelwal and Goswami and Ophioglossum costatum A Br, (now—Goswamia eliminata Zhang and Zhang; Goswamia costata Zhang and Zhang, respectively). The repeated observations of development of spores in cluster on the margins of tropophyll (leaf) from altogether different regions and localities in a different species do confirm that genes for the production of sporangia on the leaves are inherent within the genome of ophioglossaceous genera. Preliminary SEM investigations on spores have revealed unique secondary extensions of exine ornamentations with tubular outgrowths, never reported in any of the ophioglossaceous species.

In this study, non-embryogenic callus (NEC), embryogenic callus (EC), and somatic embryos (SE) sourced from various culture materials were employed to investigate somatic embryogenesis in Cinnamomum camphora. Utilizing RNA-Seq technology, we conducted transcriptome sequencing and analysis of C. camphora culture materials to elucidate the genes and metabolic pathways associated with somatic embryogenesis. Correlation analysis among the samples indicated substantial differences between the groups, confirming the representativeness of the three materials utilized. The analysis revealed three distinct databases of differentially expressed genes (DEGs) (SE vs EC, SE vs NEC, EC vs NEC) containing 10,449, 9,561, and 8,867 DEGs, respectively. Clustering analysis of DEGs unveiled significant separation among SE, EC, and NEC from different C. camphora materials. Notably, 21 genes were significantly up-regulated in SE and EC compared to NEC, predominantly comprising adversity stress-responsive genes, hormone-responsive genes, and zinc finger proteins. Of particular interest was the expression of the VACUOLAR IRON TRANSPORTER 1 (VIT1) gene, which was 78.33 and 3.05 times higher in SE than in NEC and EC, respectively. This suggests a potential crucial regulatory role for Fe²⁺ in C. camphora somatic embryogenesis. Further analysis of DEGs, in conjunction with Gene Ontology (GO) enrichment, unveiled a close association of C. camphora somatic embryogenesis with biological processes, transcriptional regulation, responses to salt stress and abscisic acid, cell nucleus activity, and DNA-binding transcription factors. Moreover, KEGG pathway analysis emphasized the significant enrichment of DEGs in plant hormone signal transduction, featuring 187 differential genes, highlighting the pivotal role of hormone signaling in C. camphora somatic embryogenesis. Most genes related to phytohormone synthesis, signal transduction, transcription factors, and stress responses were up-regulated, thereby promoting somatic embryogenesis in C. camphora. The findings of this study provide valuable insights into the molecular mechanisms underlying somatic embryogenesis in C. camphora and related species.

Roots are important organs associated with water and nutrient uptake from soil to all the plant parts. Besides plant metabolite storage organ, it also provides anchorage and mechanical support. The root “hidden half” plays a decisive role in root system architecture trait to affect grain yield and abiotic stress tolerance. Genetic study of root trait harbored due to the complex nature of root and unavailability of the rhizosphere. Identification of root system architecture provides a basic understanding of plant fitness, crop performance and grain yield. With increasing interest in root phenotyping, breeders overcome these barriers through the development of advanced phenotyping platforms based on field, laboratories and greenhouses such as soil coring, hydroponics, GLO-roots, rhizotron and mini-rhizotron. The advanced 2-D, 3-D and 4-D root imaging techniques such as magnetic resonance technique, RGB imaging, infrared thermal imaging and X-ray computed tomography are complex, but it gives the most desirable and accurate results to understand the root system architecture. This review focused on root architecture studies methods for root phenotyping using advanced recent techniques.

Many regions of Himalayas are warming more than global average rate, and treeline is assumed to be sensitive to changes in the climate. The Indian Himalayan treeline species are very less studied on water stress level and its relation to phenology. In the present study, we have tried to relate water relations of selected treeline species with the timing of phenological phases in treeline areas of western Himalayan region of Uttarakhand. The soil moisture content (S_m) varied between 33.21 and 59.16%. Most phenological phases occurred between pre-summer and summer season in all studied treeline species. The water potential (Ψ) of all the studied tree species increased just before the commencement of leafing and flowering phases when the temperature rose. The species never encountered severe water stress and the pre-dawn water potential (Ψ_PD) remained above − 1.04 MPa across all the phenological phases. Ψ_PD was most negative − 1.04 MPa during flowering period and least negative − 0.14 MPa during fruit maturation period. Morning leaf conductance (gw_AM) remained above 304.59 m mol m² s⁻¹ across all the seasons for all the studied species. Rhododendron’s species had the maximum phenological phases during summer season. The highest gw_AM was measured in Betula utilis during rainy season and minimum in R. campanulatum during winter season. Leafing and flowering both showed a positive correlation with temperature while fruiting showed a positive correlation with rainfall. The study reveals that the water potential does not reach lethal level to curtail phenological and physiological activities in treeline species. The timing of phenophases in these species is highly sensitive to seasonal rainfall and soil water availability, with temperature also directly influencing the controlling/shifting of the phenophases.

Alien species pose a potential threat to biodiversity, necessitating vigilant monitoring to inform effective control strategies and prevent their invasiveness. The primary objective of this study was to evaluate the impact of alien species on the richness, horizontal structure, and diversity of the tree–shrub layer within a Cerrado-Pantanal transition region fragment. A floristic census was conducted across a fragment of approximately 3.0 ha, measuring all individuals with an aboveground diameter (DAG) ≥ 5.0 cm. The study assessed the statistical significance of diversity variation in the presence and absence of alien species using the Hutcheson t-test and examined the correlation between the proportion of alien species and various community parameters through Pearson’s correlation. The findings revealed a total of 84 species belonging to 34 families, with a total of 2218 recorded individuals. Notably, eight species (9.52%) were identified as alien, distributed across five families. Among the alien species, Leucaena leucocephala (Lam.) de Wit exhibited the highest importance value. However, the analysis indicated that the presence of alien species did not yield a significant variation in diversity, as demonstrated by the applied test with a 5.0% probability level, at both the plot and community levels. Moreover, the correlation analysis indicated that the community variables exhibited a low association with the proportion of individuals belonging to alien species. Specifically, the correlation decreased in the following order: Shannon–Weaver Diversity Index, density of native species, basal area of native species, and richness of native species. The observed low correlation coefficients (r) and nonsignificant p-values (p < 0.05) suggested that the presence of alien species did not exert a significant influence on the richness, structure, and diversity of the tree–shrub layer within the studied fragment. This outcome was likely facilitated by the absence of dominant populations of alien species. Thus, the study concludes that, at least within this specific context, alien species do not exert a significant influence on the assessed community parameters.

The study of the rare plant species in technogenically disturbed habitats is a significant prerequisite to preserve their natural populations. Structural and functional characteristics of photosynthetic apparatus and biomass allocation in regionally rare orchid Epipactis atrorubens (Hoffm.) Besser (dark-red helleborine), colonizing two serpentine dumps post-asbestos mining (Anatol’sko-Shilovsky deposit, Sverdlovsk region, Russian), in comparison with the natural forest community were studied. Despite the adverse edaphic conditions (the high stoniness, excess some metals, low content of nutrients, water deficiency), quite numerous populations of E. atrorubens were found in transformed sites. The orchid plants colonizing the serpentine dumps were distinguished by the thicker leaf blade (by 23%), higher leaf mass per area and leaf density (by 36 and 12%, respectively), as well as reduced diffusion resistance to CO₂ (by 30%) in comparison with plants in the natural forest community. In addition, the number of cells and chloroplasts per unit leaf area of orchid leaves had increased (by 22% on average). Though orchids grew on serpentine dumps in the unfavorable conditions, the CO₂ uptake per unit leaf area and chlorophyll content decreased significantly (by 16 and 40%, respectively) only on one of the dumps, which was characterized by greater stoniness, excess light and water deficiency due to the lack of crown closure. The total fresh and dry biomass of orchid individuals from dumps was slightly less (14% on average) than that in the forest natural community. The underground biomass decreased significantly (26% on average), and at the same time aboveground biomass was higher for plant on dumps. The changes in leaf mesostructure, as well as the maintaining of photosynthetic activity contributed to stability of orchid populations in disturbed habitats. Analysis of the structural adaptations of E. atrorubens indicates that it possess a secondary ecological strategy (competitor–stress-tolerator–ruderal). Thus, the study suggests that plasticity of E. atrorubens photosynthetic apparatus promotes its successful survival in adverse environmental conditions of transformed ecosystems.