Brazilian Journal of Botany最新文献

Micropropagation of sugarcane (Saccharum spp.) using the transverse Thin Cell Layer (tTCL) is a sustainable and efficient production alternative that has promoted the rapid multiplication with the purpose of improving the productivity. The objective was to establish a protocol for increasing the number of commercial propagules through tTCL. Apical meristems of the variety Mex 69–290 were established, afterwards, explants cut by tTCL (0.3–0.5 mm) were cultivated in MS medium supplemented with 6-belcylaminopurine (BAP; 0.50, 1.00 and 1.50 mg L⁻¹) and thidiazuron (TDZ; 0.25, 0.50 and 1.00 mg L⁻¹). Two incubation conditions: photoperiod 16 h light/8 h dark and complete darkness at a temperature of 22 ± 2 °C. After 60 days, the response percentage and morphometric analysis for each of the treatments were analyzed. Regarding the percentage of response, the treatment with 1 mg L⁻¹ of TDZ in complete darkness obtained 100% survival, being the best of the treatments. For the proliferation of shoots per explant it was observed a greater number of shoots (2.25 ± 0.39) under 16 h light/8 h dark photoperiod conditions with 1 mg L⁻¹ of TDZ compared to the other concentrations of BAP and absence of photoperiod. During the acclimatization process was observed 97% of survival in plants with 1 mg L⁻¹ of TDZ under 16 h light/8 h dark. By incorporating TDZ and utilizing the tTCL technique sugarcane micropropagation can be enhanced. This approach increases the chances of obtaining a high number of plants that are suitable for commercial or investigation purpose.

Red macroalga Pyropia spiralis thrives in the upper intertidal zone and demonstrates remarkable resilience to environmental fluctuations, attributed to protective mechanisms against factors like solar radiation, temperature, and desiccation. The aim of this is study was assess the thermosensitivity and tolerance of P. spiralis, subjecting to five temperatures (15, 20, 25, 30, and 35 °C) evaluating growth rate, photosynthetic performance, and chemical composition. The hypothesis states that higher temperatures will reduce growth and photosynthesis, overstimulate metabolism, degrade pigment composition, and trigger the synthesis of protective metabolites for stabilizing cellular structures under elevated temperature conditions. The study revealed thermotolerance between 15 and 25 °C, characterized by stable energy dissipation and minimal pigment changes. Yet, at 30 and 35 °C, there was significant thermosensitivity, leading to a notable drop in photosynthesis and pigments. Carbon-to-nitrogen (C:N) ratio, notably below 20 (9.58 at 15 °C and 7.86 at 25 °C), indicated a balanced growth characterized by optimal proportions of minerals, carbohydrates, and proteins. P. spiralis ' nutritional traits make it a promising candidate for use in seaweed-based products. Analysis of specific amino acids highlighted an upward trend at 25 °C, while higher temperatures induced a thermal-response profile associated with osmoprotectants, primary stress signals, and glutathione biosynthesis. Additionally, lower temperatures were linked to increased soluble carbohydrates, whereas higher temperatures inversely impacted protein accumulation. It is crucial to note that, being just one variable, the study provides a partial perspective, highlighting the importance of future, multifactorial analyses.

This review article aims to compile updated information on the drivers of variability in floral nectar (FN), focusing mainly on concentration, volume, and metabolites. The study also seeks to organize and consolidate existing data on physicochemical variables while proposing new directions for future research. The primary conclusion of this study is that FN is not an ideally static fluid in terms of its physicochemical composition. Instead, it exhibits substantial plasticity and diversity while maintaining some regularities throughout its pre- and post-secretory processes. Therefore, a comprehensive analysis of FN—incorporating its molecular, physiological, environmental, genetic, and ecological attributes—is imperative for a holistic understanding of its drivers. Furthermore, the study determines that the phenomenon of FN variation is significantly more intricate than initially perceived. Despite considerable progress, new drivers and mechanisms of variability continue to emerge, signifying a massive knowledge gap in our pursuit of a comprehensive understanding of this phenomenon and its extensive implications for pollinators.

The subtribe Ponerinae (Orchidaceae) includes the genera Helleriella A. D. Hawkes, Isochilus R. Brown, Nemaconia Knowles & Westc., and Ponera Lindl. Most of its species are epiphytes and usually grow on trees of the genus Quercus L. in cloud forests and temperate coniferous and broad-leaved forests; some taxa are rarely lithophytes or less frequently terrestrial. The aim of this study was to estimate the distribution of the species of the subtribe Ponerinae using ecological niche models (ENM), determine areas with highest richness and endemism rates with the occurrence data and the models obtained, and determine if the areas with highest richness and endemism recognized in this work are located within any of the conservation areas (ANPs) and/or Regiones Terrestres Prioritarias (RTPs). We reviewed 1 044 herbarium specimens from ten institutional collections, corresponding to two species of Helleriella, eleven of Isochilus, six of Nemaconia, and two of Ponera, and a geographic and taxonomic database was generated. ENM were constructed with MaxEnt 3.3; and we determine areas with highest species richness and endemism with Biodiverse 4.3. Mexico is the richest country with 21 species, followed by Guatemala with nine. The more widely distributed species are: Isochilus linearis (Jacq.) R.Br, and Nemaconia striata (Lindl.) Van den Berg, Salazar & Soto Arenas; I. oaxacanus Salazar & Soto Arenas is endemic to Mexican state of Oaxaca and N. dressleriana (Soto Arenas) van den Berg, Salazar & Soto Arenas of Morelos. The cells with higher occurrence richness and occurrence weighted endemism were located in Chiapas Highlands, and the higher occurrence of corrected weighted endemism is located in Transmexican Volcanic Belt, considered the nucleus of the Mexican Transition Zone. On the other hand, the cells with greater ENM richness and ENM weighted endemism were located in Sierra Madre del Sur, and the higher ENM corrected weighted endemism in Sierra Madre Oriental. It is suggested to change the status of the regions Cañón del Zopilote and El Tlacuache from RTPs to ANPs.

The importance of medicinal and aromatic plants (MAPs) for humans has been recognized since ancient times for treating diseases of themselves and animals based on their traditional knowledge. In the past few decades, the requirement for medicinal plants has increased and resulted in their increased cultivation. However, different biotic and abiotic stresses significantly affect the growth and production of medicinal plants. Abiotic stresses such as drought, salinity, heavy metals, and cold are the primary constraints on plant biomass production and, consequently, their considerable metabolite production. Under unfavorable conditions, medicinal plants exhibit and adapt various responses at the physiological and molecular level to overcome these stresses, and it is essential to understand these responsive mechanisms to overcome the issue. This article presents data on some indigenous medicinal plants and their responses to anticipated global climate change conditions. Furthermore, applications of plant growth-promoting rhizobacteria (PGPRs), arbuscular mycorrhizal fungi (AMF), Serendipita (Piriformospora) indica, phytohormones, and nanoparticles have been summarized to overcome the impact of abiotic stress on plants in sustainable manner.

Bactris simplicifrons Mart. is considered a complex of species, due to its extensive distribution and considerable variability. Therefore, we investigated the ontogeny and morphoanatomy of its inflorescences and flowers to provide valuable biological information and identify features of interest for the taxonomy and systematics of the species and genus. To achieve this, we collected inflorescences from individuals growing in Manaus, Brazil. Based on the observed morphological characteristics, we established different developmental stages. The sampled material underwent standard protocols for light and scanning electron microscopy. This study reports for the first time, the development of connate bracts in Bactris and Arecaceae. Noteworthy is the centripetal development of the androecium, as opposed to the centrifugal pattern observed in other Bactris species. We identified traits that may be included in a phylogenetic study, such as epipetaly and the papillose style canal. The synascidiate proximal portion and symplicate distal portion of the gynoecium, becoming assimplicate in the most distal zone, is a relevant characteristic compared to other Arecaceae. Additionally, we characterized the histological arrangement of the inflorescence and each floral organ, and described the observed trichomes. Features with potential diagnostic value compared to other species in the genus include the length of stigmatic lobes, trichome morphology, absence of rigid emergence, staminal filament morphology, among others.

Investigating the effects caused by different fire frequencies on the tissue thickness of vegetative organs and the concentration of starch reserves of an invasive species in these same organs could elucidate some gaps, or be the first step towards future, further studies. In such a way, the results can contribute to understanding this species resistance mechanisms related to abiotic stress. This study aimed to understand whether fire frequency in invaded areas by Urochloa brizantha (A.Rich.) R.D.Webster caused anatomical and physiological changes in this species. Twelve samples were collected per fire treatment in areas with different event frequencies: fire exclusion, annual and biennial fires. Anatomical, histochemical and physiological analysis were performed on the leaves, rhizomes and roots. Our anatomical results showed that there was an increase in the thickness of the vascular bundle of U. brizantha leaves in the treatment of biennial burning. There were no anatomical differences in the roots. In the rhizomes, epidermis of the burned plants had greater thicknesses, the parenchyma and the vascular bundle of the biennially burned plants were more spherical than in unburned plants and in plants burned annually. These anatomical changes in grass tissues in response to fire have not yet been reported in the literature. In the physiological analyses, we found differences in the starch concentrations, with the different organs, the root presented more than 60% of the starch stored in the entire plant. Fire is changing the anatomy of this species, since there was an increase in the thickness of leaf tissues and also in rhizome tissues. The concentrations of starch in the root guaranteed plant to rapidly resprout after burning, which could be considered an advantage in post-fire environments to occupy rapidly the open spaces.

Due to their sessile nature, plants are often subjected to a plethora of abiotic (drought, heat, cold, salt and metal toxicity) and biotic (bacteria, virus, fungi and nematode) stress conditions, which constitute an immense danger to plant life and significantly impact crop growth, development, metabolism and production. It is well known that phytohormones are effective metabolites for reducing the negative impacts of abiotic and biotic stresses on agricultural plants over time. Salicylic acid is a powerful phenolic signalling biomolecule and a versatile plant growth regulator that has a key role in growth, metabolic and defence system of plants, thereby coordinating responses to pathogen attack and abiotic stress. This metabolite is crucial for the development of systemic acquired resistance (SAR) in plants because it causes the expression of genes associated with defence. Exogenous administration of SA promotes seed germination, development and blooming, up-regulates photosynthesis and boosts the activity of antioxidants that are enzymatic and non-enzymatic. Salicylic acid is an efficient signalling molecule that can modify physiological and metabolic processes in plants and can thus help in reducing environmental stress in plants over a long period of time. The less addressed issue, however, is the detailed investigation about the interaction of SA with major phytohormones as well as combined action of SA and other phytohormones that can support and influence the fundamental biochemical/physiological and molecular processes of plants against different forms of stress conditions (biotic and abiotic). The current review aims to document the detailed crosstalk of SA with other phytohormones (auxin, gibberellin, cytokinin, ethylene, abscisic acid, jasmonic acid, polyamines, melatonin, brassinosteroids and strigolactones) that confers protection and helps in the recovery of plants from different stress conditions.

Vascular cambium, a secondary meristematic tissue which by divisions of its initials results in the formation of secondary xylem (wood), were investigated in the present study to assess their impact on growth during different months of year from temperate climate of Kashmir. Fusiform initials were at their maximum and minimum dimensions during winter and summer months, respectively, while the dimensions of ray initials were maximum and minimum during summer and winter months, respectively.

Ricinus communis L., known as castor, is an oilseed crop species with increasing bioindustrial demand for its high-value oil, mainly cultivated by smallholder farming systems under abiotic stresses in semiarid areas. Abiotic stresses lead to increased reactive oxygen species production, inducing oxidative stress that damages cells and impacts seed germination and seedling establishment. Plants response to abiotic stresses involve the superoxide dismutase enzyme (SOD) that act catalyzing superoxide radical (O₂⁻) into hydrogen peroxide (H₂O₂). The characterization of RcSOD genes under heat stress and different compartments can offer valuable insights into identifying the responsive RcSOD genes. Cis-element and miRNA predictions were employed for RcSOD genes. The qPCR analysis of RcSOD gene expression was conducted during germination and early seedling stages at three distinct temperatures and also in roots, leaves, and cotyledons. Subcellular localization was performed in Nicotiana benthamiana Domin leaves. RcSOD has responsive elements in the promoter region related to abiotic stresses, and there is a possible regulation of RcCuZnSOD3 and RcCCuSOD4 by Rcmi-RNA398a-b. The RcCuZnSOD1 and RcFeSOD8 genes were upregulated by heat stress during initial germination, while RcCuZnSOD3, RcCCuSOD4, and RcFeSOD7 were upregulated during radicle protrusion and early seedling stages. Besides, the CuZnSOD and RcFeSOD8 genes were upregulated by heat stress in seedling roots. Additionally, we show the modulation of RcSOD genes in cotyledons and leaves in different stages and subcellular localization in N. benthamiana. Our results contribute to understanding RcSOD family and their potential as markers for genetic engineering or molecular-assisted breeding aimed at higher tolerance to abiotic stresses.