RESUMO

MicroRNAs play crucial regulatory roles in various aspects of development and physiology, including environmental adaptation and stress responses in teleosts. RT-qPCR is the most commonly used method for studying microRNA expression, with the accuracy and reliability of results depending on the use of an appropriate reference gene for normalization. This study aimed to evaluate seven miRNAs (U6, Let-7a, miR-23a, miR-25-3, miR-103, miR-99-5, and miR-455) expression stability in different tissues of Nile tilapia subjected to osmotic stress. Fish were divided into two groups: a control and an experimental group, raised in 0 and 12 ppt salinity water respectively. After 21 days, brain, gills, liver, and posterior intestine were collected for analysis. Different mathematical algorithms (geNorm, NormFinder, BestKeeper, and the comparative ΔCt method) were employed to identify the most suitable reference miRNAs. The results indicate that the miR-455/miR-23a combination is a robust reference for normalizing miRNA expression levels in studies of osmotic stress responses in Nile tilapia. The stability of miRNA expression can vary depending on specific stress conditions and biological processes, underscoring the necessity of selecting appropriate normalizing miRNAs for each experimental context. This study identifies reliable reference genes for future RT-qPCR analyses of miRNA expression, thereby enhancing our understanding of molecular responses in fish to environmental challenges. These insights are fundamental to the development of new technologies for the improved management and sustainability of aquaculture practices.

Assuntos

Ciclídeos , MicroRNAs , Pressão Osmótica , Reação em Cadeia da Polimerase em Tempo Real , Animais , MicroRNAs/genética , MicroRNAs/metabolismo , Ciclídeos/genética , Ciclídeos/metabolismo , Reação em Cadeia da Polimerase em Tempo Real/normas , Padrões de Referência

RESUMO

Uca maracoani is a fiddler crab found in estuaries along the western Atlantic coast, with a notable preference for euhaline environments. This study aimed to analyze the population structure and dynamics of this species in an estuary on the North Coast of Brazil, specifically in an area of the upper estuary where seasonal rainfall fluctuations result in significant changes in salinity. Monthly crab samples were taken from December 2013 to November 2015, together with measurements of environmental variables, such as water and climate parameters. The population maintains a balanced sex ratio; however, males are generally larger, with lower mortality rates and longer lifespans than females. Reproduction is continuous but mainly takes place in the dry season when salinity levels are higher (above 12‰). Higher crab densities have been observed during the rainy season when, despite lower salinity levels (below 10‰), the conditions for survival (food availability and milder climate) seem to be more favorable. The estimated average annual biomass and production for the population were 2.62 g AFDM m-2 and 5.43 g AFDM m-2 year-1, respectively, characterized by a high turnover rate (P/B = 2.10 year-1). Our results suggest that U. maracoani has thriving populations in the Amazon coast's mangroves, benefiting from the vast muddy intertidal zone and the high organic content delivered by the estuaries.

Assuntos

Braquiúros , Salinidade , Áreas Alagadas , Animais , Braquiúros/fisiologia , Brasil , Dinâmica Populacional , Estuários , Masculino , Feminino , Estações do Ano , Reprodução , Monitoramento Ambiental , Biomassa

RESUMO

Since 2000, a well-established population of the invasive oriental shrimp Palaemon macrodactylus has been present in fully marine conditions in the southwestern Atlantic Ocean (~38° S). To assess the physiological performance of this atypical population restricted to fully marine conditions, we conducted a laboratory experiment in which individuals were transferred from 35 ‰S (local seawater) to 2 ‰S; 5 ‰S; 10 ‰S; 20 ‰S; 50 ‰S and 60‰ for short (6 h), medium (48 h), and long (>504 h) acclimation periods. We measured the time course response of relevant parameters in the shrimp's hemolymph; activity of Na+, K+-ATPase (NKA), and V-H+-ATPase (VHA); and muscle water content. Shrimp showed great osmoregulatory plasticity, being able to survive for long periods between 5 ‰S and 50 ‰S, whereas no individual survived after transfer to either 2 ‰S or 60 ‰S. Shrimp hyper-regulated hemolymph osmolality at 5 ‰S and 10 ‰S, hypo-regulated at 35 ‰S and 50 ‰S, and isosmoticity was close to 20 ‰S. Compared to 35 ‰S, prolonged acclimation to 5 ‰S caused a decrease in hemolymph osmolality (~34%) along with sodium and chloride concentrations (~24%); the NKA and VHA activities decreased by ~52% and ~88%, respectively, while muscle water content was tightly regulated. Our results showed that the atypical population of P. macrodactylus studied here lives in a chronic hypo-osmo-ion regulatory state and suggest that fully marine conditions contribute to its poor performance at the lower limit of salinity tolerance (<5 ‰S).

Assuntos

Palaemonidae , Animais , Palaemonidae/fisiologia , Salinidade , Espécies Introduzidas , Hemolinfa/química , Aclimatação/fisiologia , Água do Mar/química

RESUMO

Bacterial endophytes (120) were isolated from six halophytes (Distichlis spicata, Cynodon dactylon, Eragrostis obtusiflora, Suaeda torreyana, Kochia scoparia, and Baccharis salicifolia). These halophiles were molecularly identified and characterized with or without NaCl conditions. Characterization was based on tests such as indole acetic acid (IAA), exopolysaccharides (EPS), and siderophores (SID) production; solubilization of phosphate (P), potassium (K), zinc (Zn), and manganese (Mn); mineralization of phytate; enzymatic activity (acid and alkaline phosphatase, phytases, xylanases, and chitinases) and the mineralization/solubilization mechanisms involved (organic acids and sugars). Moreover, compatibility among bacteria was assessed. Eleven halophiles were characterized as highly tolerant to NaCl (2.5 M). The bacteria isolated were all different from each other. Two belonged to Bacillus velezensis and one to B. pumilus while the rest of bacteria were identified up to the genus level as belonging to Bacillus, Halobacillus, Halomonas, Pseudomonas, Nesterenkonia, and three strains of Oceanobacillus. The biochemical responses of nutrient solubilization and enzymatic activity were different between bacteria and were influenced by the presence of NaCl. Organic acids were involved in P mineralization and nutrient solubilization. Tartaric acid was common in the solubilization of P, Zn, and K. Maleic and vanillic acid were only detected in Zn and K solubilization, respectively. Furthermore, sugars appeared to be involved in the solubilization of nutrients; fructose was detected in the solubilization tests. Therefore, these biochemical bacterial characteristics should be corroborated in vivo and tested as a consortium to mitigate saline stress in glycophytes under a global climate change scheme that threatens to exacerbate soil salinity.

RESUMO

Negative effects of salt stress may be counteracted by adequate management of sulfated nutrition. Herein, we applied 3.50, 4.25, and 5.00 mM SO42- in a nutrient solution to counteract salt stress induced by 75 and 150 mM NaCl in cabbage cv. Royal. The increase in NaCl concentration from 75 to 150 mM reduced the contents of macronutrients and micronutrients in the shoot. When increasing from 3.50 to 4.25 mM SO42-, the contents of nitrogen (N), phosphorous (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) in shoots were enhanced, at both concentrations of NaCl. Increasing from 3.50 to 4.25 mM SO42- enhanced iron (Fe), zinc (Zn), manganese (Mn), and sodium (Na) concentrations with 75 mM NaCl. With 150 mM NaCl, the increase from 3.50 to 4.25 mM SO42- enhanced the contents of Cu and Mn, but also those of Na. Chlorophylls a, b, and total decreased as the concentration of SO42- increased in plants treated with 150 mM NaCl. With 75 mM NaCl, carotenoid concentration had a positive relationship with SO42-. Hence, the 4.25 mM SO42- concentration increased the contents of macronutrients and micronutrients in the presence of 75 mM NaCl, while, with 150 mM NaCl, it improved the contents of macronutrients except K. The chlorophyll a/chlorophyll b ratio remained close to 3 when the plants were treated with 5.00 mM SO42-, regardless of NaCl. Similarly, this level of SO42- increased the concentration of carotenoids, which translated into reductions in the total chlorophyll/carotenoid ratios, indicating a protective effect of the photosynthetic apparatus. It is concluded that higher doses of sulfur favor the accumulation of nutrients and increase the concentration of carotenoids under salt stress.

RESUMO

Climate change intensifies soil salinization and jeopardizes the development of crops worldwide. The accumulation of salts in plant tissue activates the defense system and triggers ethylene production thus restricting cell division. We hypothesize that the inoculation of plant growth-promoting bacteria (PGPB) producing ACC (1-aminocyclopropane-1-carboxylate) deaminase favors the development of arbuscular mycorrhizal fungi (AMF), promoting the growth of maize plants under saline stress. We investigated the efficacy of individual inoculation of PGPB, which produce ACC deaminase, as well as the co-inoculation of PGPB with Rhizophagus clarus on maize plant growth subjected to saline stress. The isolates were acquired from the bulk and rhizospheric soil of Mimosa bimucronata (DC.) Kuntze in a temporary pond located in Pernambuco State, Brazil. In the first greenhouse experiment, 10 halophilic PGPB were inoculated into maize at 0, 40 and 80 mM of NaCl, and in the second experiment, the PGPB that showed the best performance were co-inoculated with R. clarus in maize under the same conditions as in the first experiment. Individual PGPB inoculation benefited the number of leaves, stem diameter, root and shoot dry mass, and the photosynthetic pigments. Inoculation with PGPB 28-10 Pseudarthrobacter enclensis, 24-1 P. enclensis and 52 P. chlorophenolicus increased the chlorophyll a content by 138%, 171%, and 324% at 0, 40 and 80 mM NaCl, respectively, comparing to the non-inoculated control. We also highlight that the inoculation of PGPB 28-10, 28-7 Arthrobacter sp. and 52 increased the content of chlorophyll b by 72%, 98%, and 280% and carotenoids by 82%, 98%, and 290% at 0, 40 and 80 mM of NaCl, respectively. Co-inoculation with PGPB 28-7, 46-1 Leclercia tamurae, 70 Artrobacter sp., and 79-1 Micrococcus endophyticus significantly increased the rate of mycorrhizal colonization by roughly 50%. Furthermore, co-inoculation promoted a decrease in the accumulation of Na and K extracted from plant tissue, with an increase in salt concentration, from 40 mM to 80 mM, also favoring the establishment and development of R. clarus. In addition, co-inoculation of these PGPB with R. clarus promoted maize growth and increased plant biomass through osmoregulation and protection of the photosynthetic apparatus. The tripartite symbiosis (plant-fungus-bacterium) is likely to reprogram metabolic pathways that improve maize growth and crop yield, suggesting that the AMF-PGPB consortium can minimize damages caused by saline stress.

Assuntos

Bactérias , Carbono-Carbono Liases , Micorrizas , Raízes de Plantas , Microbiologia do Solo , Zea mays , Zea mays/microbiologia , Zea mays/crescimento & desenvolvimento , Micorrizas/fisiologia , Carbono-Carbono Liases/metabolismo , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Bactérias/classificação , Bactérias/metabolismo , Bactérias/isolamento & purificação , Estresse Salino , Clorofila/metabolismo , Glomeromycota/fisiologia , Tolerância ao Sal , Fotossíntese , Rizosfera , Cloreto de Sódio/metabolismo , Folhas de Planta/microbiologia , Solo/química

RESUMO

Seed conditioning with ultraviolet light (UV-C) might (1) improve crop yield and quality, (2) reduce the use of agrochemicals during cultivation, and (3) increase plant survival in high salinity environments. The aim of this study was to examine the effects of UV-C conditioning of white oat seeds at two doses (0.85 and 3.42 kJ m-2) under salinity stress (100 mM NaCl). Seeds were sown on germination paper and kept in a germination chamber at 20°C. Germination and seedling growth parameters were evaluated after 5 and 10 days. Data demonstrated that excess salt reduced germination and initial growth of white oat seedlings. In all the variables analyzed, exposure of seeds to UV-C under salt stress exerted a positive effect compared to non-irradiated control. The attenuating influence of UV-C in germination was greater at 0.85 than at 3.42 kJ m-2. Thus, data indicate that conditioning white oat seeds in UV-C light produced greater tolerance to salt stress. These findings suggest that UV-C conditioning of white oat seeds may be considered as a simple and economical strategy to alleviate salt-induced stress.

Assuntos

Avena , Germinação , Sementes , Raios Ultravioleta , Avena/efeitos dos fármacos , Avena/efeitos da radiação , Avena/crescimento & desenvolvimento , Sementes/efeitos da radiação , Sementes/efeitos dos fármacos , Sementes/crescimento & desenvolvimento , Germinação/efeitos dos fármacos , Germinação/efeitos da radiação , Estresse Salino/efeitos dos fármacos , Plântula/efeitos da radiação , Plântula/efeitos dos fármacos , Plântula/crescimento & desenvolvimento , Cloreto de Sódio

RESUMO

Plant electrophysiology has unveiled the involvement of electrical signals in the physiology and behavior of plants. Spontaneously generated bioelectric activity can be altered in response to changes in environmental conditions, suggesting that a plant's electrome may possess a distinct signature associated with various stimuli. Analyzing electrical signals, particularly the electrome, in conjunction with Machine Learning (ML) techniques has emerged as a promising approach to classify characteristic electrical signals corresponding to each stimulus. This study aimed to characterize the electrome of common bean (Phaseolus vulgaris L.) cv. BRS-Expedito, subjected to different water availabilities, seeking patterns linked to these stimuli. For this purpose, bean plants in the vegetative stage were subjected to the following treatments: (I) distilled water; (II) half-strength Hoagland's nutrient solution; (III) -2 MPa PEG solution; and (IV) -2 MPa NaCl solution. Electrical signals were recorded within a Faraday's cage using the MP36 electronic system for data acquisition. Concurrently, plant water status was assessed by monitoring leaf turgor variation. Leaf temperature was additionally measured. Various analyses were conducted on the electrical time series data, including arithmetic average of voltage variation, skewness, kurtosis, Probability Density Function (PDF), autocorrelation, Power Spectral Density (PSD), Approximate Entropy (ApEn), Fast Fourier Transform (FFT), and Multiscale Approximate Entropy (ApEn(s)). Statistical analyses were performed on leaf temperature, voltage variation, skewness, kurtosis, PDF µ exponent, autocorrelation, PSD ß exponent, and approximate entropy data. Machine Learning analyses were applied to identify classifiable patterns in the electrical time series. Characterization of the electrome of BRS-Expedito beans revealed stimulus-dependent profiles, even when alterations in water availability stimuli were similar in terms of quality and intensity. Additionally, it was observed that the bean electrome exhibits high levels of complexity, which are altered by different stimuli, with more intense and aversive stimuli leading to drastic reductions in complexity levels. Notably, one of the significant findings was the 100% accuracy of Small Vector Machine in detecting salt stress using electrome data. Furthermore, the study highlighted alterations in the plant electrome under low water potential before observable leaf turgor changes. This work demonstrates the potential use of the electrome as a physiological indicator of the water status in bean plants.

Assuntos

Phaseolus , Água , Folhas de Planta

RESUMO

Cotton is one of the most exploited crops in the world, being one of the most important for the Brazilian Northeast. In this region, the use of irrigation is often necessary to meet the water demand of the crop. Water is often used from underground wells that have a large amount of salt in their constitution, which can compromise the development of crops, so it is vital to adopt strategies that reduce salt stress effects on plants, such as the foliar application of hydrogen peroxide. Thus, the objective of this study was to evaluate the effects of foliar application of hydrogen peroxide on the gas exchange, growth, and production of naturally colored cotton under salt stress in the semi-arid region of Paraíba, Brazil. The experiment was carried out in a randomized block design in a 5 × 5 factorial scheme, with five salinity levels of irrigation water-ECw (0.3, 2.0, 3.7, 5.4 and 7.1 dS m-1)-and five concentrations of hydrogen peroxide-H2O2 (0, 25, 50, 75 and 100 µM), and with three replicates. The naturally colored cotton 'BRS Jade' had its gas exchange, growth, biomass production, and production reduced due to the effects of salt stress, but the plants were able to produce up to the ECw of 3.97 dS m-1. Foliar application of hydrogen peroxide at the estimated concentrations of 56.25 and 37.5 µM reduced the effects of salt stress on the stomatal conductance and CO2 assimilation rate of cotton plants under the estimated ECw levels of 0.73 and 1.58 dS m-1, respectively. In turn, the concentration of 12.5 µM increased water-use efficiency in plants subjected to salinity of 2.43 dS m-1. Absolute and relative growth rates in leaf area increased with foliar application of 100 µM of hydrogen peroxide under ECw of 0.73 and 0.3 dS m-1, respectively. Under conditions of low water salinity (0.3 dS m-1), foliar application of hydrogen peroxide stimulated the biomass formation and production components of cotton.