Brazilian Journal of Botany最新文献

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.

In taxonomic studies, in addition to floral characteristics, the structural characteristics of the vegetative organs also contribute to the taxonomic determination of the species. To provide information regarding these characteristics in the genus Tetramerium, a structural, micromorphological and histochemical analysis of cross sections of the leaves was performed using histochemical techniques and optical and scanning electron microscopy of two of its species, T. glutinosum, endemic to Mexico, and the widely distributed T. tenuissimum, was conducted. The two species presented amphistomatic leaves; double palisade chlorenchyma on adaxial and abaxial surfaces, leaf unifacial; vascular bundle sheaths with kranz anatomy; intradermal and subepidermal cystoliths of various shapes and sizes; nonglandular trichomes osteolate with a thin-walled conical head, glandular trichomes, including a new type, the straight, bright-ringed tricellular trichomes, and a variety of multicellular glandular trichomes. The glandular trichomes secrete waxes or oleoresins and mucilage deposited on the surfaces abaxial and adaxial in the form of platelets, granules and threads or strands. The histochemistry of the cystoliths highlights the presence of proteins and polysaccharides as a product of the possible superposition of the cell wall and plasmalemma lamellae. All these characteristics are typical of species from semi-arid habitats and correspond to the defense function against biotic and abiotic agents assigned to trichomes and their secretions in other studies of various genera and families, as well as to the adaptation function to these habitats of the kranz structure, which was novel for the genus Tetramerium.

As a famous and widely planted shoot-use bamboo species, few researches have been focused on the micropropagation of Dendrocalamus brandisii. This study established an efficient micropropagation system of D. brandisii through seeds and cutoff nodal buds from the multiple shoots in vitro. The orthogonal tests were employed to screen out the optimal disinfection time and hormone combination for multiple shoot induction, proliferation in vitro and root induction in vitro. The results showed that the optimal disinfection time was 10 min. MS medium containing 3 mg L⁻¹ BA, 0.5 mg L⁻¹ KT, 0.10 mg L⁻¹ NAA and 25 g L⁻¹ sucrose showed the highest multiplication rates, and those supplemented with 5 mg L⁻¹ BA, 0.5 mg L⁻¹ KT, 1.0 mg L⁻¹ NAA and 25 g L⁻¹ sucrose were the best for shoot proliferation. 1/2 MS medium supplemented with the hormone combination of 0.1 mg L⁻¹ IBA, and 1.0 mg L⁻¹ NAA was optimal for root induction. For plantlets regeneration from the single nodal buds of multiple shoots, the optimal medium was MS + BA 2.0 mg L⁻¹ + NAA 0.5 mg L⁻¹ for shoot multiplication and 1/2MS + BA 0.1 mg L⁻¹ + NAA 2.0 mg L⁻¹ for root induction. The optimal acclimatization medium was vermiculite + perlite (1:1). This study firstly and systematically established the micropropagation system of D. brandisii by using the seeds and nodal buds of the multiple shoots as explants. Multiple shoots induced from the cutoff nodal buds of the multiple shoots could further expand the micropropagation efficiency.

Abstract

The Brazil nut tree (Bertholletia excelsa Bonpl.), one of the main species from the socioeconomic and ecological point of view of the Amazon, is characterized by slow and uneven germination. Considering that its genetic constitution is a determining factor for the morphology and physiology of germination, we investigated different Brazil nut tree genotypes regarding morphophysiological seed traits and performed a morphoanatomical description of the leaves. Genotypes showed differences in seed morphology, imbibition curve, germination rate, and germination speed index, and also, in some of the morphoanatomical leaf structures. The genotype 606 showed the best physiological performance during germination, mainly in terms of water imbibition, as it needs to absorb less water and achieve a higher germination percentage than the genotype Sant Fé, in addition to a higher stomatal index. In the evaluated genotypes, quintenary venation was observed in the leaves, different from a leaf from a wild matrix. Our findings aid the morphoanatomical differentiation of different genotypes of B. excelsa, and represent a significant step forward for clonal propagation, as well as providing a route for improving these species’ physiological and genetic characteristics.

Graphical abstract

Ferula ferulaeoides (Steud.) Korov. is a well-known perennial herb whose growth and distribution are negatively affected by drought. However, the drought sensitivity of its seed germination stage and early seedling growth stage have not been studied in detail. In this study, PEG-6000 induced water deficiency conditions were perform to obverse the drought tolerance of seeds and seedlings of F. ferulaeoides. Data exhibited that the seed germination rate was reduced with elevated PEG-6000 concentrations and especially, no seeds germinated at a PEG-6000 concentration of 20%. Besides, water deficiency conditions altered the morphology of seedling leaf and root, which made the chloroplast of seedling leaf cells deformed and vacuolized and caused mitochondria structure damage in both tissues. The antioxidant parameters of seedlings under drought stress were further observed. Data exhibited that catalase, peroxidase, and superoxide dismutase responded rapidly under drought stress. The seedlings accumulated a large amount of malondialdehyde under high drought stress. Drought stress affected the accumulation of proline and photosynthetic pigments. In summary, the germination and seedling stage of F. ferulaeoides exhibited poorly environmental adaptability to drought stress, which mainly manifested in the water-dependent changes of seed survival rate, seedling morphology, physiological and biochemical indexes. Our results could provide guiding suggestions for future artificial cultivation.

Tectaria Cav. is the largest genus of Tectariaceae. Species delimitation in the genus is challenging due to morphological convergence. In this study, we have sequenced the complete chloroplast genome of Tectaria coadunata (J.Sm.) C.Chr. and compared it with other plastome sequences of Tectaria for gene composition and structural variations. The plastome size of T. coadunata was 148,333 bp with one Large Single Copy (LSC; 82,508 bp), Small Single Copy (SSC; 18,965 bp), and duplicated inverted repeat (IR; 23,430 bp) region. The plastome of Tectaria exhibited the absence of genes ccsA, rpl32, as well as two tRNAs, trnP-GGG and trnL-UAG. Nevertheless, nuclear encoded copies of all genes were successfully recovered from the transcriptome of T. coadunata. This is the first report of gene deletion from Tectaria plastome. Seven intergenic spacer regions, viz. ycf1-chlN, atpF-atpH, psbM-petN, ndhE-psaC, trnT-trnfM, psbK-psbI, and trnC-trnG, were identified with high nucleotide diversity (Pi) values. These regions can be used as DNA barcodes for species delimitation in Tectaria. Furthermore, peculiar insertions were observed in the IR region. Phylogenetic analysis placed T. coadunata as a sister to T. decurrens.

Grevillea robusta is an important plant in Proteaceae, decoding and understanding the chloroplast genome of G. robusta is of great theoretical significance and practical value to the genetic diversity and phylogenetic relationships of Proteaceae. In this work, the chloroplast genome of G. robusta was sequenced, characterized, and compared to the other Proteaceae species to provide chloroplast genetic resources and because the information on chloroplast genes is scarce in the Proteaceae, we also examined the affinities between G. robusta and species of various families within Proteales to determine G. robusta’s phylogenetic position. Based on the illumina sequencing data of G. robusta, the sequencing results were assembled and annotated utilizing the software tools GetOrganelle and CPGAVAS2. The chloroplast genome data for the genera Macadamia, Helicia, and Protea were obtained from the NCBI database. Subsequently, the chloroplast genomes of four genera within the Proteaceae family were subjected to analysis using various programs including MISA, REPuter, IRscope, and IQtree. The chloroplast genome of G. robusta was 158,642 bp in length and consists of 129 genes, including 84 protein-coding genes, 37 tRNA genes and 8 rRNA genes. Fifty-six simple repeat sequences were obtained from G. robusta, of which single-nucleotide repeats were the most (66.07%) and the six nucleotide repeats were the least (1).Simultaneously, the chloroplast genome of G. robusta exhibited the presence of 34 repeats, primarily consisting of palindrome repeats (16). The inverted repeat (IR) region of G. robusta did not undergo a significant contraction/expansion event, in contrast to the notable contraction observed in Protea kilimandscharica. Analysis of gene selection pressure indicated positive selection signals in the ycf1 genes. Furthermore, examination of RNA editing sites revealed the occurrence of 148 RNA editing sites within the protein-coding genes of the chloroplast genome of G. robusta, with the majority consisting of C/U editing, accounting for 54.73% of the total. Phylogenetic analysis confirmed that G. robusta belongs to Proteaceae, and grouped with Helicia and Macadamia, with a support value of 100%. The chloroplast genome of G. robusta was assembled successfully, which is closely related to the chloroplast genomes of Helicia and Macadamia, and belongs to the same clade as Proteaceae. The results of this study laid a foundation for understanding the systematic evolution of Proteaceae plants and provide rich data to support the development of molecular biological information, such as molecular markers.

Although progression of genome-based techniques has been revamping several areas of genetic engineering, reliable and efficient procedures are expected to unveil structural and functional information of genes. Many methods such as chromosome walking and molecular cloning that are used to recognize unknown flanking sequences are effortful and time-consuming. Here, we report the identification of an unknown upstream regulatory region of actin gene from Plectranthus amboinicus and eight other medicinal plants using thermal asymmetric interlaced PCR (TAIL PCR). As actin is a ubiquitous protein that plays a significant role in developmental stages of plants, we set out to isolate the 5′ flanking region of the actin gene. Three heterologous gene-specific primers were designed based on plant Arabidopsis actin conserved sites, and arbitrary degenerate primers were used for the isolation of putative promoter sequence. Successful amplification was observed in most of the plants tested, thus proving that TAIL PCR is an efficient, effective, and economic procedure for the isolation of promoter sequences from various plants.

Graphic abstract

The genus Smilax (Smilacaceae), commonly known as Sarsaparilla, comprises about 262 species with numerous medicinal and economic importance. Due to considerable morphological similarity, Smilax has been recognized as a taxonomically challenging group. In this study, we conducted a comprehensive analysis of the genomic architecture and nucleotide variation within the genus Smilax, comparing the newly sequenced plastome of Smilax zeylanica with ten other plastomes. Our analyses revealed a highly conserved gene structure, order, and orientation across the plastomes studied. Nonetheless, we identified eight highly divergent regions, namely rbcL-accD, petA-psbJ, psaJ-rpl33, ndhC-trnV UAC, accD-psaI, ndhF-rpl32, trnK UUU, and rps16-trnQ UUG. These highly diverse DNA regions could potentially be used as DNA super-barcodes for the precise identification of Smilax species. Furthermore, our study identified four positively selected genes—accD, matK, psaA, and rbcL. We also observed the loss of infA and pseudogenization of ycf15 and ycf68 genes within Smilacaceae. Additionally, the prediction of RNA editing sites revealed a high level of conservation across the genus Smilax. These findings provide valuable insights into adaptation, evolutionary dynamics, marker development, and barcode validation in Smilax, ultimately enhancing its therapeutic applications.