Search Results (25)

Background/Objectives: Actinobacteria are one of the largest bacterial phyla. These microbes produce bioactive compounds, such as antifungals, antibiotics, immunological modulators, and anti-tumor agents. Studies on actinobacteria isolated from the Brazilian Savannah biome (Cerrado) are scarce and mostly address metagenomics or the search for hydrolytic enzyme-producing microbes. Solanum lycocarpum (lobeira) is a tree widely employed in regional gastronomy and pharmacopeia in Central Brazil. Methods: In this work, 60 actinobacteria isolates were purified from the rhizosphere of S. lycocarpum. Eight Streptomyces spp. isolates were selected for in vitro antifungal activity against Cryptococcus neoformans H99, the C. neoformans 89-610 fluconazole-tolerant strain, C. gattii NIH198, Candida albicans, C. glabrata, and C. parapsilosis. The ability of the aqueous extracts of the isolates to induce the in vitro secretion of tumor necrosis factor (TNF-α), nitric oxide (NO), interleukin-6 (IL-6), and IL-10 by murine macrophages was also evaluated. Results: All extracts showed antifungal activity against at least two yeast species. Streptomyces spp. LAP11, LDB2, and LDB17 inhibited C. neoformans growth by 40–93%. Most extracts (except LAP2) also inhibited C. gattii. None inhibited C. albicans, but all inhibited C. glabrata (40–90%). Streptomyces sp. LAP8 extract increased nitric oxide production by approximately 347-fold in murine macrophages, while LDB11 extract suppressed LPS-induced TNF-α production by 70% and simultaneously increased IL-10 secretion, suggesting immunosuppressive potential. Conclusions: The results revealed that Cerrado actinobacteria-derived aqueous extracts are potential sources of antifungal and immunomodulatory biocompounds. Full article

The Pantanal, considered the world’s largest floodplain, exhibits hydrological and ecological dynamics that are intrinsically linked to water inflows from the surrounding highlands. While the impacts of large-scale climatic phenomena and land-use changes on hydrological variables within the Upper Paraguay River Basin (UPRB) are acknowledged, their combined effects remain unknown. Recent reductions in precipitation and river discharge have adversely affected both environmental and socioeconomic aspects of the Cerrado (Brazilian Savannah) and Pantanal biomes in Brazil, raising concerns about the long-term sustainability of these important ecosystems. This study analyzes a 37-year hydrological time series (1986–2023) of rainfall, streamflow, and flooded area in three contributing basins of the Pantanal (Jauru—JB; Taquari—TB; and Miranda—MB), and reveals distinct hydrological trends influenced by different climate systems. Significant decreasing trends in rainfall and streamflow were observed in the northern JB and TB, contrasted by increasing trends in the southern MB. Consequently, a declining trend in downstream flooded areas within the Pantanal floodplain was identified. Long-term memory processes (Hurst phenomena) were identified in the time series of the Pantanal flooded area and also in the Paraguay river stage data. These findings indicate a persistent and aggregated reduction in the Pantanal’s hydrologic variables, adversely affecting its water-dependent ecology and economic activities, such as ranching, fishing, and navigation. This study underscores the necessity of adaptative management strategies to tackle the impacts of water surface loss, increased fire risks, and climate variability in the UPRB. Full article

Understanding how assemblages are structured is important for ecology, especially in tropical regions that exhibit high biodiversity and are currently experiencing high rates of loss and modification of natural environments caused by anthropogenic impacts. Understanding the structuring of assemblages across different regions at different spatial scales allows us to comprehend how environmental modifications can affect biodiversity on a local and regional scale. The objective of this study was to evaluate the biodiversity of Odonata species using taxonomic diversity metrics (richness and composition) in areas of Cerrado, Atlantic Forest, and Caatinga and to evaluate which sets of local and spatial environmental variables are associated with these assemblages among the different areas evaluated. The study was conducted in the state of Bahia, where 49 streams were sampled, including 17 in the Atlantic Forest, 18 in the Caatinga, and 15 in the Cerrado. Our results demonstrate a high diversity of Odonata species, with 95 species collected. We found a similar species richness among the regions sampled. However, each region presented a distinct composition, with greater similarity between the Cerrado and the Caatinga. Spatial predictors along with some environmental variables were associated with the Caatinga and Cerrado. Some environmental variables, such as the amount of riparian vegetation and aquatic vegetation, were associated with the Cerrado. The results highlighted that each of the evaluated regions are fundamental for maintaining and conserving the regional dragonfly biodiversity. The lack of conservation of aquatic ecosystems in the different regions leads to local species loss and, consequently, to a loss of regional Odonata biodiversity. Full article

The Cerrado is Brazil’s second largest biome, covering continuous areas in several states. Covering approximately 23% of Brazil’s territory, the Cerrado biome connects with all the main biomes in South America, thus forming a major biological corridor. This biome is one of those that has suffered the most from the incidence of wildfires, leading to a progressive depletion of the region’s natural resources. The aim of this study was to evaluate the use of an Unmanned Aerial Vehicle (UAV) embedded with an RGB sensor to obtain high-resolution digital products that can be used to identify areas of the Brazilian Cerrado affected by wildfires. The study was carried out in a savannah biome area selecting a vegetation corridor with native vegetation free from anthropogenic influence. The following UAV surveys were carried out before and after a burning event. Once the orthomosaics of the area were available, the GLI, VARI, ExG and NGRDI vegetation indices were used to analyze the vegetation. The data indicate that the B band and the GLI and ExG indices are more suitable for environmental impact analysis in Cerrado areas affected by fires, providing a solid basis for environmental monitoring and management in scenarios of fire disturbance. Full article

In Brazil, several silicic rocks can be used as powder-based K sources, which can reduce production costs in agriculture. The optimized supply of K not only increases yield but also contributes to soil fertility preservation and long-term sustainability by curtailing nutrient losses and reducing the risk of nutrient imbalances. Therefore, this study aimed to investigate the effects of K application timing, source, and doses on nodulation, productive components, and productivity of soybeans in a not-tillage system in the Savannah. The experiment was carried out in the field, for two years, in an Oxisol, with a clayey texture. The experimental design was in random blocks, in a 2 × 4 × 3 factorial scheme, as follows: two application timings (early and sowing), four K₂O rates (0, 40, 80, and 120 kg ha⁻¹), and three sources (KCl, Potasil, and Ekosil), with four replicates. Potassium fertilizer was broadcasted on the soil without incorporation into the soil. Due to the interactions between doses and K₂O sources, there was a linear adjustment for KCl sources, the higher the dose, the lower the nodule mass. Also, for nodule mass, the interaction between dose and application time was significant for the early application of the Ecosil and Potasil sources for 80 kg ha⁻¹. The highest estimated soybean grain productivity was 3262 kg ha⁻¹ with 78 kg ha⁻¹ of K₂O, being the most suitable for growing soybeans under a no-tillage system. Full article

Context-dependence in mutualisms is a fundamental aspect of ecological interactions. Within plant-ant mutualisms, particularly in terms of biotic protection and pollination, research has predominantly focused on elucidating the benefits while largely overlooking potential costs. This notable gap underscores the need for investigations into the drawbacks and trade-offs associated with such mutualistic relationships. Here, we evaluated the role of pericarpial nectaries (PNs) in shaping the dynamics of ant-pollinator mutualisms. Specifically, we investigated whether ants visiting the PN of Palicourea rigida (Rubiaceae) could deter hummingbirds and disrupt pollination, ultimately influencing fruit production. Our research involved manipulative experiments and observation of ant-pollinator interactions on P. rigida plants in the Brazilian savannah. We found that visiting ants can deter hummingbirds and/or disrupt pollination in P. rigida, directly influencing fruit set. However, these results are species-specific. The presence of very aggressive, large predatory ants, such as E. tuberculatum, had a negative impact on hummingbird behavior, whereas aggressive mid-sized ants, such as C. crassus, showed no effects. Our study illuminates the multifaceted aspects of ant-plant mutualisms and underscores the importance of evaluating costs and unexpected outcomes within these ecological relationships. Full article

The Brazilian savannah region, characterized by high average temperatures, well-defined rainy and dry seasons, soil with low productive potential, and high pressure for parasitic diseases, is home to the highest percentage of the beef herd, which is the world’s largest commercial beef producer. Therefore, breeds that present rusticity combined with productivity are the focus of research in cattle breeding in the region. Considering their geographic particularities and their effects on the animals’ blood parameters, the objective was to study the behavior of hematological variables, serum biochemistry, and acute phase proteins in beef calves at weaning age. Jugular blood samples were collected in a single day from 30 weaning calves (about eight months old and 200 kg of body weight) from the following breeds: Nellore, Senepol, Nellore × Aberdeen Angus cross, Nellore × Senepol cross, and Nellore × Aberdeen Angus × Senepol cross. Hematological data were obtained using an automatic cell counter, serum biochemical measurements were obtained using commercial kits, and the electrophoretogram was obtained using the SDS-page technique. In general, the results were consistent with data already published in similar situations regarding health status, age, and level of metabolic activity. However, differences observed between groups can be explained by differences observed in other concurrent variables like temperament. The pure zebu breed was more reactive than pure taurine. While crossbreds showed intermediate values, and parasitic infestation, the pure taurine breed with higher parasite infestation, while the zebu breed had lower values, which produced effects in some laboratory tests, and generated differences between breeds. In conclusion, the reference intervals available for healthy animals can be routinely used without interference from the geographic region for animals produced without nutritional failures as long as changes are recorded in pathological, infectious, metabolic, or nutritional deficiency situations. However, it is suggested that a study covering a larger number of herds may demonstrate a greater geographic effect on the studied variables. Full article

Jelly palm (Butia capitata) is a species of palm tree endemic to the Brazilian Savannah (Cerrado) Biome, which stands out for its use as food, which has resulted in a predatory exploitation of its natural populations. This study aimed to characterize fruits and diaspores of natural populations of jelly palm (‘Arinos’, ‘Mirabela’ and ‘Serranópolis’), in addition to developing ex situ conservation strategies of the species, through the storage of zygotic embryos at ultra-low temperatures of liquid nitrogen (LN). Initially, fruits, seeds and embryos were evaluated for their morphological characteristics. For conservation, hydrated zygotic embryos were desiccated for up to 12 h in a laminar-flow chamber and immersed directly in LN with different moisture contents. As a result, we observed morphological differences among the studied populations. The population ‘Arinos’ showed more expressive results for most of the evaluated characteristics, such as length, width of fruits and seeds. The cryopreservation of zygotic embryos proved to be efficient for the conservation of the species reaching germination rates between 70 and 86%, when the moisture content of the embryos immersed in LN were between 10 and 14%. The plants that reached the stage of the greenhouse had a rate of more than 80% survival. The variability in the characteristics of fruits and diaspores of the analyzed populations allow for establishing divergent groups for the definition of conservation strategies or genetic improvement. The developed cryopreservation protocol can be considered simple and efficient for the conservation of the genetic variability of the species. Full article

Botanical biopesticides have emerged as sustainable and eco-friendly alternatives to synthetic pesticides, whose indiscriminate use leads to several drawbacks to human and environmental health. To the best of our knowledge, there have been no reports on M. pubescens’ bioactivity on phytopathogens affecting crops as a potential fungicide or antifeedant. This has encouraged us to investigate the potential of the roots of this plant as a source of biopesticides. The present study reports on the evaluation of the roots extract from Magonia pubescens A. St.-Hill., a species from the Cerrado (Brazilian savannah), on the phytopathogenic fungi Botrytis cinerea, Fusarium oxysporum, and Alternaria alternata. In addition, its insect antifeedant effect was assayed against Chrysodeixis chalcites. Thus, an in vitro test-assay was used to determine the fungicide potential (percentage growth inhibition, % GI) of the ethanolic extract of this plant species, whereas a leaf-disk bioassay on the 5th instar larvae of C. chalcites was performed to evaluate its insecticidal potential. The ethanolic extract was further fractionated by liquid–liquid partition using solvents of increasing polarity. The hexane/dichloromethane fraction exhibited a moderated potency and was similar to the ethanolic extract on the three assayed fungi (around % GI 30 at 1 mg/mL), whereas the n-butanol fraction showed a slight improvement of the fungicide effect against B. cinerea (% GI 39.18 at 1 mg/mL). Moreover, the ethanolic extract exhibited a strong antifeedant activity, with a refusal rate (FR) higher than 90% in both choice and non-choice assays against C. chalcites, while the ethyl acetate and n-butanol fractions behaved as appetite suppressors. These results highlight M. pubescens as a promising source of biopesticides and deserve further investigations to optimize extraction procedures. Full article

Healthy soil biota is the key to meeting the world population’s growing demand for food, energy, fiber and raw materials. Our aim is to investigate the effect of green manure as a strategy to recover the macrofauna and the chemical properties of soils which have been anthropogenically degraded. The experiment was a completely randomized block design with four replicates. Green manure, Urochloa decumbens, with or without application of limestone and gypsum, composed the integrated systems. The macroorganisms as well as the soil fertility were analyzed after 17 years of a process of soil restoration with the aforementioned systems. The succession of Stizolobium sp. with Urochloa decumbens, with limestone and gypsum, was teeming with termites, beetles and ants. This integrated system presented the most technically adequate indexes of diversity and uniformity. Multivariate models showed a substantial increase in the total number of individuals due to the neutralization of harmful elements and the gradual release of nutrients by limestone and plaster. These conditioners have undergone multiple chemical reactions with the substrate in order to balance it chemically, thus allowing the macroinvertebrates to grow, develop, reproduce and compose their food web in milder microclimates. It was concluded that the integration of green manure together with grass is an economical and environmentally correct strategy to restore the macrofauna properties of degraded soil in the Brazilian savannah. Full article

The evaluation of water and energy cycles from the estimation of water balance is a fundamental instrument to assess the water potential of a region. Thus, the objective of this study was to evaluate the probable monthly water deficit and surplus in Cerrado river basins and the trend of monthly data on climatic water balance (CWB) and its input variables in the study region. Monthly data on precipitation (P) and reference evapotranspiration (ETo) from January 2003 to December 2019 were used. The deficit and the probable monthly water surplus were obtained from the CWB for each of the 4531 ottobasins. For this, the frequency equal to or greater than 80% of permanence in time was used as a reference. Trend analysis was applied. In the rainy season, most ottobasins showed positive CWB. On the other hand, in the period of lower water availability, most ottobasins showed a negative balance. In all months, there was some ottobasin with a significant trend both for CWB and for P and ETo. In most situations, these trends were a decrease in CWB and monthly P and an increase in monthly ETo. Full article

Wheat is one of the staple foods of the global population due to its adaptability to a wide range of environments. Nitrogen is one of the crucial limiting factors in wheat production and is considered a challenge to food security. Therefore, sustainable agricultural technologies such as seed inoculation with plant growth-promoting bacteria (PGPBs) can be adopted to promote biological nitrogen fixation (BNF) for higher crop productivity. In this context, the objective of the current study was to evaluate the effects of nitrogen fertilization and seed inoculations with Azospirillum brasilense, Bacillus subtilis and A. brasilense + B. subtilis on agronomic and yield attributes, grain yield, grain N accumulation, N use efficiency and applied N recovery in Brazilian Cerrado, which consists of gramineous woody savanna. The experiment was carried out in two cropping seasons in Rhodic Haplustox soil under a no-tillage system. The experiment was designed in a randomized complete block in a 4 × 5 factorial scheme, with four replications. The treatments consisted of four seed inoculations (control—without inoculation, inoculation with A. brasilense, B. subtilis and A. brasilense + B. subtilis) under five N doses (0, 40, 80, 120 and 160 kg ha⁻¹, applied from urea) at the wheat tillering stage. Seed co-inoculation with A. brasilense + B. subtilis increased grain N accumulation, number of spikes m⁻¹, grains spike⁻¹ and grain yield of wheat in an irrigated no-tillage system of tropical savannah, regardless of the applied N doses. Nitrogen fertilization at a dose of 80 kg ha⁻¹ significantly increased grain N accumulation and number of grains spikes⁻¹ and nitrogen use efficiency. Recovery of applied N was increased with inoculation of B. subtilis and co-inoculation of A. brasilense + B. subtilis at increasing N doses. Therefore, N fertilization can be reduced by the inclusion of co-inoculation with A. brasilense + B. subtilis in the cultivation of winter wheat under a no-tillage system of Brazilian Cerrado. Full article

Hippeastrum stapfianum (Kraenzl.) R.S.Oliveira & Dutilh (Amaryllidaceae) is an endemic plant species from the Brazilian savannah with biological and pharmacological potential. This study evaluated the effects of ethanol extract from H. stapfianum leaves on acetylcholinesterase enzyme activity and the action on nuclear receptors PPAR-α and PPAR-γ. A gene reporter assay was performed to assess the PPAR agonist or antagonist activity with a non-toxic dose of H. stapfianum ethanol extract. The antioxidant capacity was investigated using DPPH^• scavenging and fosfomolybdenium reduction assays. The identification of H. stapfianum‘s chemical composition was performed by gas chromatography–mass spectrometry (GC-MS) and HPLC. The ethanol extract of H. stapfianum activated PPAR-α and PPAR-γ selectively, inhibited the acetylcholinesterase enzyme, and presented antioxidant activity in an in vitro assay. The major compounds identified were lycorine, 7-demethoxy-9-O-methylhostasine, and rutin. Therefore, H. stapfianum is a potential source of drugs for Alzheimer’s disease due to its ability to activate PPAR receptors, acetylcholinesterase inhibition activity, and antioxidant attributes. Full article

A successful microbial inoculant can increase root colonization and establish a positive interaction with native microorganisms to promote growth and productivity of cereal crops. Zinc (Zn) is an intensively reported deficient nutrient for maize and wheat production in Brazilian Cerrado. It can be sustainably managed by inoculation with plant growth-promoting bacteria and their symbiotic association with other microorganisms such as arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSE). The objective of this study was to evaluate the effect of Azospirillum brasilense inoculation and residual Zn rates on root colonization and grain yield of maize and wheat in succession under the tropical conditions of Brazil. These experiments were conducted in a randomized block design with four replications and arranged in a 5 × 2 factorial scheme. The treatments consisted of five Zn rates (0, 2, 4, 6 and 8 kg ha⁻¹) applied from zinc sulfate in maize and residual on wheat and without and with seed inoculation of A. brasilense. The results indicated that root colonization by AMF and DSE in maize–wheat cropping system were significantly increased with interaction of Zn rates and inoculation treatments. Inoculation with A. brasilense at residual Zn rates of 4 kg ha⁻¹ increased root colonization by AMF under maize cultivation. Similarly, inoculation with A. brasilense at residual Zn rates of 2 and 4 kg ha⁻¹ reduced root colonization by DSE under wheat in succession. The leaf chlorophyll index and leaf Zn concentration were increased with inoculation of the A. brasilense and residual Zn rates. The inoculation did not influence AMF spore production and CO₂-C in both crops. The grain yield and yield components of maize–wheat were increased with the inoculation of A. brasilense under residual Zn rates of 3 to 4 kg ha⁻¹ in tropical savannah conditions. Inoculation with A. brasilense under residual Zn rates up to 4 kg ha⁻¹ promoted root colonization by AMF and DSE in the maize cropping season. While the inoculation with A. brasilense under 2 and 4 kg ha⁻¹ residual Zn rates reduced root colonization by AMF and DSE in the wheat cropping season. Therefore, inoculation with A. brasilense in combination with Zn fertilization could consider a sustainable approach to increase the yield and performance of the maize–wheat cropping system in the tropical savannah conditions of Brazil. Full article

Brazil has a large share of hydropower in its electricity matrix. Since hydropower depends on water availability, it is particularly vulnerable to drought events, making the Brazilian electricity matrix vulnerable to climate change. Starting in 2005, Brazil opened the matrix to new renewable sources, including sugarcane-based electricity. Sugarcane is known for its resilience to short dry spells. Over the last decades, its production area moved from the coastal plains of the Atlantic Forest biome to the savannahs of the Cerrado biome, which is characterised by a five- to six month-long dry season. The sugarcane-based electricity system is highly dynamic and complex due to the interlinkages, dependencies, and cascading impacts between its agricultural and industrial subsystems. This paper applies the risk framework proposed by the IPCC to assess climate-change-driven drought risks to sugarcane electricity generation systems to identify their strengths and weaknesses, considering the system dynamics and linkages. Our methodology aims to understand and characterize drought in the agriculture as well as industrial subsystems and offers a specific understanding of the system by using indicators tailored to sugarcane-based electricity generation. Our results underline the relevance of actions at different levels of management. Initiatives, such as regional weather forecasts specifically for agriculture, and measures to increase industrial water-use efficiency were identified to be essential to reduce the drought risk. Actions from farmers and mill owners, supported and guided by the government at different levels, have the potential to increase the resilience of the system. For example, the implementation of small dams was identified by local actors as a promising intervention to adapt to the long dry seasons; however, they need to be implemented based on a proper technical assessment in order to locate these dams in suitable places. Moreover, the results show that creating and maintaining small water reservoirs to enable the adoption of deficit-controlled irrigation technology contribute to reducing the overall drought risk of the sugarcane-based electricity generation system. Full article