RESUMO
Azospirillum argentinense Az19 is an osmotolerant plant growth-promoting bacterium that protects maize plants from drought. In this work, we explored the role of trehalose in the superior performance of Az19 under stress. The trehalase-coding gene treF was constitutively expressed in Az19 through a miniTn7 system. The resulting recombinant strain, Az19F, did not accumulate trehalose, was affected in its capacity to cope with salt-, osmotic-, and UV-stress, and showed higher reactive oxygen species levels. Physiological alterations were also observed under normal conditions, such as increased growth in biofilms, higher motility, and decreased auxin secretion. Even so, the capacity of Az19F to colonize maize roots was not affected, either under normal or drought conditions. When inoculated in maize, both Az19 and Az19F strains promoted plant growth similarly under normal irrigation. However, unlike Az19, the trehalose-deficient strain Az19F could not improve the height, aerial fresh weight, or relative water content of maize plants under drought. Notably, Az19F triggered an exacerbated oxidative response in the plants, resulting in higher levels of antioxidant and phenolic compounds. We conclude that the role of trehalose metabolism in A. argentinense Az19 transcends stress tolerance, being also important for normal bacterial physiology and its plant growth-promoting activity under drought. KEY POINTS: ⢠Trehalose is required by Az19 for full tolerance to salt-, osmotic-, and UV-stress. ⢠A restriction in trehalose accumulation alters Az19 normal cell physiology. ⢠Trehalose contributes to Az19-induced maize growth promotion under drought.
Assuntos
Azospirillum , Secas , Trealose , Zea mays , Zea mays/microbiologia , Zea mays/metabolismo , Zea mays/crescimento & desenvolvimento , Trealose/metabolismo , Azospirillum/genética , Azospirillum/metabolismo , Azospirillum/fisiologia , Raízes de Plantas/microbiologia , Estresse Fisiológico , Espécies Reativas de Oxigênio/metabolismo , Trealase/metabolismo , Trealase/genética , Pressão Osmótica , Biofilmes/crescimento & desenvolvimentoRESUMO
Amazon forests are becoming increasingly vulnerable to disturbances such as droughts, fires, windstorms, logging, and forest fragmentation, all of which lead to forest degradation. Nevertheless, quantifying the extent and severity of disturbances and their cumulative impact on forest degradation remains a significant challenge. In this study, we combined multispectral data from Landsat sensors with hyperspectral data from the Earth Observing-One (Hyperion/EO-1) sensor to evaluate the efficacy of multiple vegetation indices in detecting forest responses to disturbances in an experimentally burned forest in southeastern Amazonia. Our experimental area was adjacent to an agricultural field and consisted of three 50-ha treatments - an unburned Control, a plot burned every three years, and a plot burned annually from 2004 to 2010. All plots were monitored to assess vegetation recovery after fire disturbance. These areas were also affected by three drought events (2007, 2010, and 2016) over the study period. We evaluated a total of 18 Vegetation Indices (VI), one unique to Landsat, 12 unique to Hyperion/EO-1, and five commons to both satellites (i.e., 6 total from Landsat and 17 from Hyperion). We used linear models (LM) to evaluate how changes in ground observations of forest structure (biomass, leaf area index [LAI], and litter production) associated with fire were captured by the two VIs most sensitive to forest degradation. Our results indicate that the Plant Senescence Reflectance Index (PSRI) derived from Hyperion/EO-1 was the most sensitive to vegetation changes associated with forest fires, increasing by 94% in burned vs. unburned forests. Of the Landsat-derived VIs, we found that the Green-Red Normalized Difference (GRND) were the most sensitive to forest degradation by fire, showing a marked decline (87%) in the burned plots compared with the unburned Control. However, compared to PSRI, the GRND was a better predictor of changes associated with fire, both in the forest interior or forest edge, for the three ground variables: biomass stocks (r2 = 0.5-0.8), LAI (r2 = 0.8-0.9), and litter production (r2 = 0.4-0.7). This study demonstrate that VIs can detect forest responses to fire and other disturbances over time, highlighting the relative strengths of each VI. In doing so, it shows how the integration of multispectral and hyperspectral data can be useful for monitoring tropical forest degradation and recovery. Moreover, it provides valuable insights into the limitations of existing approaches, which can inform the design of next-generation sensors for global forest monitoring.
Assuntos
Florestas , Incêndios , Conservação dos Recursos Naturais/métodos , Árvores , Secas , Brasil , Ecossistema , Monitoramento Ambiental/métodosRESUMO
As the world's climate continues to change, human populations are exposed to increasingly severe and extreme weather conditions that can promote migration. Here, we examine how extreme weather influences the likelihood of undocumented migration and return between Mexico and the United States. We used data from 48,313 individuals observed between 1992 and 2018 in 84 Mexican agricultural communities. While controlling for regional and temporal confounding factors, we related individual decisions to migrate to the United States without documents and subsequently return to Mexico with lagged weather deviations from the historical norm during the corn-growing season (May to August). Undocumented migration was most likely from areas experiencing extreme drought, and migrants were less likely to return to their communities of origin when extreme weather persisted. These findings establish the role of weather shocks in undocumented Mexican migration to, and eventual settlement in, the United States. The findings also suggest that extreme weather conditions, which are likely to increase with climate change, promote clandestine mobility across borders and, thus, expose migrants to risks associated with crossing dangerous terrain and relying upon smugglers.
Assuntos
Mudança Climática , Emigração e Imigração , Tempo (Meteorologia) , México , Humanos , Estados Unidos , Emigração e Imigração/estatística & dados numéricos , Migração Humana , Clima Extremo , Imigrantes Indocumentados/estatística & dados numéricos , SecasRESUMO
Tropical biodiversity is undergoing unprecedented changes due to the hydrological cycle intensification, characterized by more intense droughts and wet seasons. This raises concerns about the resilience of animal and plant communities to such extremes and the existence of potential refugia-areas theorized to safeguard biological communities from adverse climate impacts. Over 20 years of monitoring in Central Amazonia, we investigated the short-term and long-term effects of hydrological cycle intensification on bird, fish, ant, and palm communities. We explored whether the 'insurance effect' of climate trends (droughts buffered by preceded wet seasons) or 'environmental refugia' (droughts or floods buffered by topographic features) could lessen the impact of climate events on community composition, richness, evenness, and species rank. Pronounced abundance changes were observed among animal species, whereas palm species showed relative temporal stability. Birds and fish were more affected by the immediate and long-term severity of droughts and wet periods, while ants responded primarily to short-term drought impacts. Conversely, palm communities exhibited delayed responses to climate extremes, primarily in long-term comparisons. As expected, the proposed 'insurance effect' mitigates the long-term impacts of extreme climate events on animal and plant community trends. However, less extreme hydrological conditions linked to topographic features did not provide effective 'environmental refugia' for animals or plants during adverse climate conditions. These outcomes underscore the complex and varied biological responses to ongoing climate change, challenging the prevailing assumptions about the efficacy of environmental refugia and highlighting the nuanced resilience of biodiversity in Central Amazonia.
A biodiversidade tropical está passando por mudanças sem precedentes devido à intensificação do ciclo hidrológico, caracterizada por secas mais intensas e estações chuvosas mais severas. Isso gera preocupações sobre a resiliência das comunidades de animais e plantas a esses extremos e a existência de potenciais refúgios áreas teoricamente capazes de proteger as comunidades biológicas dos impactos climáticos adversos. Em mais de 20 anos de monitoramento na Amazônia Central, investigamos os efeitos de curto e longo prazo da intensificação do ciclo hidrológico sobre as comunidades de aves, peixes, formigas e palmeiras. Exploramos se o 'efeito seguro' das tendências climáticas (secas amortecidas por estações chuvosas precedentes) ou 'refúgios ambientais' (secas ou cheias amortecidas por características topográficas) poderiam atenuar o impacto dos eventos climáticos na composição das comunidades, riqueza, equidade e mudança na abundância das espécies. Mudanças pronunciadas na abundância foram observadas entre as espécies animais, enquanto as palmeiras apresentaram relativa estabilidade temporal. Aves e peixes foram mais afetados pela severidade imediata e de longo prazo das secas e períodos chuvosos, enquanto as formigas responderam principalmente aos impactos de secas de curto prazo. Em contrapartida, as palmeiras mostraram respostas atrasadas aos extremos climáticos, principalmente em comparações de longo prazo. Como esperado, o 'efeito seguro' proposto atenua os impactos de longo prazo de eventos climáticos extremos nas tendências das comunidades de animais e plantas. No entanto, condições hidrológicas menos extremas associadas a características topográficas não forneceram refúgios ambientais efetivos para animais ou plantas durante condições climáticas adversas. Esses resultados destacam as respostas biológicas complexas e variadas às mudanças climáticas em curso, desafiando as suposições predominantes sobre a eficácia dos refúgios ambientais e ressaltando a resiliência sutil da biodiversidade na Amazônia Central.
Assuntos
Formigas , Biodiversidade , Aves , Mudança Climática , Peixes , Florestas , Animais , Aves/fisiologia , Formigas/fisiologia , Peixes/fisiologia , Brasil , Secas , Arecaceae/fisiologia , Arecaceae/crescimento & desenvolvimento , Estações do AnoRESUMO
The advancement of digital agriculture combined with computational tools and Unmanned Aerial Vehicles (UAVs) has opened the way to large-scale data collection for the calculation of vegetation indices (VIs). These vegetation indexes (VIs) are useful for agricultural monitoring, as they highlight the inherent characteristics of vegetation and optimize the spatial and temporal evaluation of different crops. The experiment tested three coffee genotypes (Catuaí 62, E237 and Iapar 59) under five water regimes: (1) FI 100 (year-round irrigation with 100% replacement of evapotranspiration), (2) FI 50 (year-round irrigation with 50% evapotranspiration replacement), (3) WD 100 (no irrigation from June to September (dry season) and, thereafter, 100% evapotranspiration replacement), (4) WD 50 (no irrigation from June to September (water stress) and, thereafter, 50% evapotranspiration replacement) and (5) rainfed (no irrigation during the year). The irrigated treatments were watered with irrigation and precipitation. Most indices were highest in response to full irrigation (FI 100). The values of the NDVI ranged from 0.87 to 0.58 and the SAVI from 0.65 to 0.38, and the values of these indices were lowest for genotype E237 in the rainfed areas. The indices NDVI, OSAVI, MCARI, NDRE and GDVI were positively correlated very strongly with photosynthesis (A) and strongly with transpiration (E) of the coffee trees. On the other hand, temperature-based indices, such as canopy temperature and the TCARI index correlated negatively with A, E and stomatal conductance (gs). Under full irrigation, the tested genotypes did not differ between the years of evaluation. Overall, the index values of Iapar 59 exceeded those of the other genotypes. The use of VIs to evaluate coffee tree performance under different water managements proved efficient in discriminating the best genotypes and optimal water conditions for each genotype. Given the economic importance of coffee as a crop and its susceptibility to extreme events such as drought, this study provides insights that facilitate the optimization of productivity and resilience of plantations under variable climatic conditions.
Assuntos
Irrigação Agrícola , Coffea , Secas , Genótipo , Irrigação Agrícola/métodos , Coffea/genética , Coffea/fisiologia , Água , Produtos Agrícolas/genética , Produtos Agrícolas/fisiologia , Estresse Fisiológico/genéticaRESUMO
AIMS: Drought is one of the most destructive abiotic factors for agricultural production, causing considerable yield losses. Quinoa (Chenopodium quinoa Willd.) is cultivated worldwide in different environmental conditions due to its nutritional characteristics and ability to grow in harsh environments. This study aims to select drought stress tolerant rhizosphere bacteria from the Bolivian altiplano to evaluate their quinoa growth-promoting capacity, including in vitro germination, seedling growth under drought stress in greenhouse conditions and field studies. METHODS AND RESULTS: Rhizosphere soil from the southern highlands of Bolivia was collected to isolate 164 drought-stress tolerant bacteria. From these, 28 strains were shown to produce indole acetic acid, and/or to possess nitrogen-fixing or phosphate solubilizing capacity under in vitro conditions. Furthermore, all strains were evaluated for improvement of in vitro quinoa seed germination. Based on these properties, nine bacterial strains were formulated in three different matrixes and evaluated for quinoa seedling growth promotion during drought stress in a 3-month greenhouse experiment. Three strains were shown to significantly (P < 0.05) increase root length of the quinoa seedlings. One strain was selected and shown to significantly (P < 0.05) increase leaf number in a field trial under semi-arid conditions in the southern altiplano in Bolivia. DNA sequencing and phylogenetic analyses of the 16S locus putatively identified the three strains with growth-promoting potential under drought stress as members of the genera Bacillus, Pseudomonas, and Serratia. CONCLUSION: Microorganisms from the arid Bolivian altiplano constitute a potential biological source of bioinoculants to improve quinoa productivity and provide sustainable mitigation of climate change effects.
Assuntos
Bactérias , Chenopodium quinoa , Secas , Germinação , Rizosfera , Microbiologia do Solo , Bolívia , Bactérias/genética , Bactérias/classificação , Bactérias/isolamento & purificação , Bactérias/metabolismo , Plântula/crescimento & desenvolvimento , Plântula/microbiologia , Raízes de Plantas/microbiologia , Raízes de Plantas/crescimento & desenvolvimento , Estresse Fisiológico , Resistência à SecaRESUMO
La presente publicación describe el contexto y los procesos del cambio climático global, sus repercusiones reales o probables en la salud y la forma en que deberían responder las sociedades humanas y sus gobiernos frente a los desastres de sequías, dedicando especial atención al sector de la salud
Assuntos
Humanos , Masculino , Feminino , Mudança Climática , Assistência Integral à Saúde , Desastres , Meio Ambiente , SecasRESUMO
Drought stress is a key limitation for plant growth and colonization of arid habitats. We study the evolution of gene expression response to drought stress in a wild tomato, Solanum chilense, naturally occurring in dry habitats in South America. We conduct a transcriptome analysis under standard and drought experimental conditions to identify drought-responsive gene networks and estimate the age of the involved genes. We identify two main regulatory networks corresponding to two typical drought-responsive strategies: cell cycle and fundamental metabolic processes. The metabolic network exhibits a more recent evolutionary origin and a more variable transcriptome response than the cell cycle network (with ancestral origin and higher conservation of the transcriptional response). We also integrate population genomics analyses to reveal positive selection signals acting at the genes of both networks, revealing that genes exhibiting selective sweeps of older age also exhibit greater connectivity in the networks. These findings suggest that adaptive changes first occur at core genes of drought response networks, driving significant network re-wiring, which likely underpins species divergence and further spread into drier habitats. Combining transcriptomics and population genomics approaches, we decipher the timing of gene network evolution for drought stress response in arid habitats.
Assuntos
Secas , Redes Reguladoras de Genes , Solanum , Estresse Fisiológico , Solanum/genética , Estresse Fisiológico/genética , Transcriptoma/genética , Adaptação Fisiológica/genética , Perfilação da Expressão Gênica , Ecossistema , Evolução Molecular , Regulação da Expressão Gênica de Plantas , América do Sul , Seleção GenéticaRESUMO
PREMISE: Vascular epiphytes of tropical montane cloud forests are vulnerable to climate change, particularly as cloud bases elevate and reduce atmospheric inputs to the system. However, studies have generally focused on epiphytes in contiguous forests, with little research being done on epiphytes on isolated pasture trees. We investigated water relations of pasture-tree epiphytes at three sites located below and above the elevation of the average cloud base in Monteverde, Costa Rica. METHODS: We measured sap velocity and four microclimate variables in both the dry and wet season of 2018. We also measured functional traits, including pressure volume (PV) curves, predawn/midday water potential, and various lab-based water relations traits. We used linear mixed models to assess the correlation between microclimate and sap velocity in both seasons and ANOVA to assess the variation in PV curve and water potential variables. RESULTS: The turgor loss point generally increased from the wettest to driest site. However, this trend was driven primarily by the increasing prevalence of leaf succulence at drier sites. Microclimatic variables correlated strongly with sap velocity in the wet season, but low soil moisture availability caused this correlation to break down during the dry season. CONCLUSIONS: Our results emphasize the vulnerability of cloud forest epiphytes to rising cloud bases. This vulnerability may be more severe in pasture trees that lack the potential buffer of surrounding forest, but additional research that directly compares the canopy microclimate conditions between forest and pasture trees is needed to confirm this possibility.
Assuntos
Secas , Microclima , Árvores , Clima Tropical , Costa Rica , Árvores/fisiologia , Água/fisiologia , Mudança Climática , Estações do AnoRESUMO
KEY MESSAGE: Climate change can limit yields of naturally resilient crops, like sorghum, challenging global food security. Agriculture under an erratic climate requires tapping into a reservoir of flexible adaptive loci that can lead to lasting yield stability under multiple abiotic stress conditions. Domesticated in the hot and dry regions of Africa, sorghum is considered a harsh crop, which is adapted to important stress factors closely related to climate change. To investigate the genetic basis of drought stress adaptation in sorghum, we used a multi-environment multi-locus genome-wide association study (MEML-GWAS) in a subset of a diverse sorghum association panel (SAP) phenotyped for performance both under well-watered and water stress conditions. We selected environments in Brazil that foreshadow agriculture where both drought and temperature stresses coincide as in many tropical agricultural frontiers. Drought reduced average grain yield (Gy) by up to 50% and also affected flowering time (Ft) and plant height (Ph). We found 15 markers associated with Gy on all sorghum chromosomes except for chromosomes 7 and 9, in addition to loci associated with phenology traits. Loci associated with Gy strongly interacted with the environment in a complex way, while loci associated with phenology traits were less affected by G × E. Studying environmental covariables potentially underpinning G × E, increases in relative humidity and evapotranspiration favored and disfavored grain yield, respectively. High temperatures influenced G × E and reduced sorghum yields, with a ~ 100 kg ha-1 average decrease in grain yield for each unit increase in maximum temperature between 29 and 38 °C. Extreme G × E for sorghum stress resilience poses an additional challenge to breed crops for moving, erratic weather conditions.
Assuntos
Secas , Sorghum , Sorghum/genética , Sorghum/fisiologia , Sorghum/crescimento & desenvolvimento , Fenótipo , Estresse Fisiológico/genética , Mudança Climática , Brasil , Interação Gene-Ambiente , Adaptação Fisiológica/genética , Estudo de Associação Genômica Ampla , Locos de Características Quantitativas , Estudos de Associação Genética , Loci Gênicos , Resistência à SecaRESUMO
The aim of this study was to compare the food consumption of the population of Coari, Amazonas State, Brazil, according to the NOVA Classification, during the hydrological phases of drought and flooding of the Amazon rivers. An epidemiological, population-based, cross-sectional study was carried out. The sample consisted of 457 adult individuals. Data were collected in two stages using a sociodemographic instrument, a 24-hour food recall and a food frequency questionnaire adapted to local habits. The data were analyzed using the statistical program R version 4.2.4, using Pearson's chi-square, Fischer's exact and Bhapkar's tests. The sample was predominantly female (drought = 70%/flood = 71.2%) and brown (drought = 65.4%/flood = 66.2%). Most of the interviewees ate meals (breakfast, lunch and dinner). Afternoon snacks were the most common intermediate meal, especially during flooding (274/70.2%). In natura or minimally processed foods predominated at the three main meals (95%). Ultra-processed foods were consumed little or not at all and were mentioned especially during the drought (152/33.3%; p = 0.007). On the other hand, consumption of regional foods (tucumã, beiju, tapioca flour and açaí) increased during the flood (p < 0.001). Consumption of in natura or minimally processed foods continues to be the mainstay of the diet in the interior of Amazonas, with a predominance of regional foods during the flood and processed and ultra-processed foods during the drought, demonstrating the influence, albeit subtle, of the hydrological phases on the food consumption of this population.
O objetivo foi comparar o consumo alimentar da população de Coari, Amazonas, Brasil, segundo a Classificação NOVA, durante as fases hidrológicas de seca e inundação dos rios amazônicos. Realizou-se um estudo epidemiológico, de base populacional e transversal. A amostra foi composta por 457 indivíduos adultos e a coleta de dados foi realizada em dois momentos, mediante um instrumento sociodemográfico, um recordatório alimentar de 24 horas, e um questionário de frequência alimentar adaptado para os hábitos locais. Os dados foram analisados pelo programa estatístico R versão 4.2.4, por meio dos testes qui-quadrado de Pearson, exato de Fischer e de Bhapkar. A amostra foi composta predominantemente pelo sexo feminino (seca = 70%/inundação = 71,2%) e pardos (seca = 65,4%/inundação = 66,2%). As refeições (café da manhã, almoço e jantar) foram realizadas pela maior parte dos entrevistados. O lanche da tarde foi a refeição intermediária mais realizada, principalmente na inundação (274/70,2%). Predominou-se o consumo de alimentos in natura ou minimamente processados nas três principais refeições (95%). Os ultraprocessados são pouco ou não são consumidos e foram citados especialmente na seca (152/33,3%; p = 0,007). Em contrapartida, o consumo de alimentos regionais (tucumã, beiju, farinha de tapioca e açaí) aumentou durante a inundação (p < 0,001). O consumo de alimentos in natura ou minimamente processados continua sendo a base da alimentação no interior do Amazonas, predominando alimentos regionais na inundação e alimentos processados e ultraprocessados na seca, demonstrando a influência, ainda que sutil, das fases hidrológicas no consumo alimentar dessa população.
El objetivo de este estudio fue comparar el consumo de alimentos de la población de Coari, Amazonas, Brasil, según la Clasificación NOVA, durante las fases hidrológicas de sequía e inundación de los ríos amazónicos. Se trató de un estudio epidemiológico, poblacional y transversal. La muestra estuvo conformada por 457 individuos adultos. Los datos se recogieron en dos etapas mediante un instrumento sociodemográfico, un recordatorio de alimentos las 24 horas, y un cuestionario de frecuencia alimentar adaptado a las costumbres locales. Para el análisis de datos se utilizó el programa estadístico R versión 4.2.4, mediante las pruebas chi-cuadrado de Pearson, exacto de Fisher y de Bhapkar. Hubo un mayor predominio del sexo femenino (sequía = 70%/inundación = 71,2%) y de pardos (sequía = 65,4%/inundación = 66,2%). La mayoría de los entrevistados tuvieron sus comidas (desayuno, almuerzo y cena) en el período analizado. La merienda fue la comida intermedia más frecuente, especialmente en la inundación (274/70,2%). El consumo de alimentos in natura o mínimamente procesados predominó en las tres comidas principales (95%). Los productos ultraprocesados fueron poco o nada consumidos y se los mencionaron especialmente en la sequía (152/33,3%; p = 0,007). Por otro lado, el consumo de alimentos regionales (tucumã, beiju, harina de tapioca y açaí) tuvo un aumento durante la inundación (p < 0,001). El consumo de alimentos in natura o mínimamente procesados sigue siendo la base alimentar en el interior de la Amazonía, con predominio en el consumo de alimentos regionales en la inundación y de alimentos procesados y ultraprocesados en la sequía, lo que evidencia la influencia, aunque discreta, de las fases hidrológicas en el consumo de alimentos de esta población.
Assuntos
Secas , Comportamento Alimentar , Inundações , Fatores Socioeconômicos , População Urbana , Humanos , Feminino , Brasil , Estudos Transversais , Masculino , Adulto , Comportamento Alimentar/fisiologia , Pessoa de Meia-Idade , Adulto Jovem , Fatores Sociodemográficos , Adolescente , Inquéritos e QuestionáriosRESUMO
The theory of ecological speciation posits that adaptive divergence among incipient species raises incidental barriers to reproduction, thus catalyzing the emergence of new species. In this study, we conducted an experimental test of this theory in Galápagos finches, a clade in which beaks and mating songs are mechanistically linked. We forecasted the acoustic structure of songs for a set of possible evolutionary futures (successive droughts spurring increasingly large beaks) and, in a field assay, presented resulting song simulations to territorial males. We found that responses to songs dropped off after six simulated drought events, to degrees roughly comparable to drops in response to songs that diverged through cultural drift and acoustic adaptation. Our results support, in Darwin's finches, the feasibility and mechanistic bases of an ecological speciation hypothesis.
Assuntos
Bico , Tentilhões , Especiação Genética , Vocalização Animal , Animais , Tentilhões/genética , Tentilhões/fisiologia , Masculino , Bico/anatomia & histologia , Equador , Secas , Feminino , Evolução Biológica , Comportamento Sexual AnimalRESUMO
Higher temperatures exacerbate drought conditions by increasing evaporation rates, reducing soil moisture and altering precipitation patterns. As global temperatures rise as a result of climate change, these effects intensify, leading to more frequent and severe droughts. This link between higher temperatures and drought is particularly evident in sensitive ecosystems like the Amazon rainforest, where reduced rainfall and higher evaporation rates result in significantly lower water levels, threatening biodiversity and human livelihoods. As an example, the serious drought experienced in the Amazon basin in 2023 resulted in a significant decline in fish populations. Elevated water temperatures, reaching up to 38°C, led to mass mortality events, because these temperatures surpass the thermal tolerance of many Amazonian fish species. We know this because our group has collected data on critical thermal maxima (CTmax) for various fish species over multiple years. Additionally, warmer waters can cause hypoxia, further exacerbating fish mortality. Thus, even Amazon fish species, which have relatively high thermal tolerance, are being impacted by climate change. The Amazon drought experienced in 2023 underscores the urgent need for climate action to mitigate the devastating effects on Amazonian biodiversity. The fact that we have been able to link fish mortality events to data on the thermal tolerance of fishes emphasizes the important role of experimental biology in elucidating the mechanisms behind these events, a link that we aim to highlight in this Perspective.
Assuntos
Mudança Climática , Secas , Peixes , Animais , Biodiversidade , Brasil , Peixes/fisiologia , Floresta ÚmidaRESUMO
In May and June 2024, a die-off of Mexican mantled howler monkeys (Alouatta palliata mexicana) occurred in southern Mexico. This commentary documents the event, attributing it to extreme heatwaves, drought, wildfires, and habitat impoverishment. Despite their reported resilience to habitat disturbances, mantled howler monkey mortality rate in some areas reached 31%. Key evidence points to heatstroke as the primary cause of death, exacerbated by limited hydration and reduced dietary diversity in disturbed habitats. Immediate responses included community-led rescues (e.g., hydrating the monkeys), coordination of rescue activities by nongovernmental organizations (NGOs) (e.g., managing donations), involvement of scientists (e.g., monitoring of primate populations), and assistance from government officials (e.g., providing legal support for animal management). This event underscores the urgency of developing action plans to prevent and attend future crises. Among other actions, we highlight (i) establishing primate care infrastructure with medical and rehabilitation centers; (ii) developing protocols and training programs to ensure rapid crisis response; (iii) fostering collaboration among government, NGOs, and academic institutions for effective crisis management; and (iv) developing targeted research on climate change impacts, predictive models, and long-term health monitoring. We emphasize the critical need for coordinated conservation efforts to protect wild primates and maintain natural ecosystem resilience in the face of escalating climate challenges.
Assuntos
Alouatta , Ecossistema , Animais , México , Alouatta/fisiologia , Conservação dos Recursos Naturais , Secas , Incêndios FlorestaisRESUMO
MAIN CONCLUSION: Despite modulating senescence and drought responses, the GmERD15-like subfamily members are differentially induced by multiple stresses and diverge partially in stress signaling functions. The PAM2 motif represents a binding site for poly (A)-binding proteins (PABPs), often associated with RNA metabolism regulation. The PAM2-containing protein ERD15 stands out as a critical regulator of diverse stress responses in plants. Despite the relevance of the PAM2 motif, a comprehensive analysis of the PAM2 superfamily and ERD15-like subfamily in the plant kingdom is lacking. Here, we provide an extensive in silico analysis of the PAM2 superfamily and the ERD15-like subfamily in soybean, using Arabidopsis and rice sequences as prototypes. The Glycine max ERD15-like subfamily members were clustered in pairs, likely originating from DNA-based gene duplication, as the paralogs display high sequence conservation, similar exon/intron genome organization, and are undergoing purifying selection. Complementation analyses of an aterd15 mutant demonstrated that the plant ERD15-like subfamily members are functionally redundant in response to drought, osmotic stress, and dark-induced senescence. Nevertheless, the soybean members displayed differential expression profiles, biochemical activity, and subcellular localization, consistent with functional diversification. The expression profiles of Glyma04G138600 under salicylic acid (SA) and abscisic acid (ABA) treatments differed oppositely from those of the other GmERD15-like genes. Abiotic stress-induced coexpression analysis with soybean PABPs showed that Glyma04G138600 was clustered separately from other GmERD15s. In contrast to the AtERD15 stress-induced nuclear redistribution, Glyma04G138600 and Glyma02G260800 localized to the cytoplasm, while Glyma03G131900 fractionated between the cytoplasm and nucleus under normal and stress conditions. These data collectively indicate that despite modulating senescence and drought responses, the GmERD15-like subfamily members are differentially induced by multiple stresses and may diverge partially in stress signaling functions.
Assuntos
Arabidopsis , Regulação da Expressão Gênica de Plantas , Glycine max , Proteínas de Plantas , Estresse Fisiológico , Glycine max/genética , Glycine max/fisiologia , Glycine max/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Estresse Fisiológico/genética , Arabidopsis/genética , Secas , Oryza/genética , Oryza/metabolismo , Oryza/fisiologia , Filogenia , Família MultigênicaRESUMO
Fleshy fruit metabolism is intricately influenced by environmental changes, yet the hormonal regulations underlying these responses remain poorly elucidated. ABA and ethylene, pivotal in stress responses across plant vegetative tissues, play crucial roles in triggering fleshy fruit ripening. Their actions are intricately governed by complex mechanisms, influencing key aspects such as nutraceutical compound accumulation, sugar content, and softening parameters. Both hormones are essential orchestrators of significant alterations in fruit development in response to stressors like drought, salt, and temperature fluctuations. These alterations encompass colour development, sugar accumulation, injury mitigation, and changes in cell-wall degradation and ripening progression. This review provides a comprehensive overview of recent research progress on the roles of ABA and ethylene in responding to drought, salt, and temperature stress, as well as the molecular mechanisms controlling ripening in environmental cues. Additionally, we propose further studies aimed at genetic manipulation of ABA and ethylene signalling, offering potential strategies to enhance fleshy fruit resilience in the face of future climate change scenarios.
Assuntos
Ácido Abscísico , Etilenos , Frutas , Reguladores de Crescimento de Plantas , Estresse Fisiológico , Etilenos/metabolismo , Ácido Abscísico/metabolismo , Frutas/crescimento & desenvolvimento , Frutas/fisiologia , Frutas/metabolismo , Frutas/genética , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/fisiologia , SecasRESUMO
Drought is a primary ecological stress limiting wheat yield in water-deficient regions. Conducting targeted genetic selection of wheat cultivars can expedite the adaptation process of wheat to the climatic conditions of the region, allowing for the identification of high-yielding varieties with stable genetic traits. This study investigated the impact of the TaGW8 and TaGS3A genes, known for their contribution to wheat productivity. The effective productivity genes TaGW8-B1b/B1a and the TaGS5-3A-T genome exert a 32.8% influence on the variability of the 1000 grain weight (TGW) trait. This influence stems from both individual genes and their interactions, with at least 17.5% of TGW variability explained by the gene combinations examined in the study. Notably, the TaGS5-3A-T gene exhibits a significant positive correlation with total yield, exceeding 63%. The integration of these productivity genes, based on field phenotypic data, has resulted in an overall yield increase of selected samples by 0.8 tons/ha compared to the country's average multi-year indicator.
Assuntos
Genes de Plantas , Triticum , Triticum/genética , Cazaquistão , Fenótipo , Estações do Ano , Genótipo , SecasRESUMO
Predicting how plants respond to drought requires an understanding of how physiological mechanisms and drought response strategies occur, as these strategies underlie rates of gas exchange and productivity. We assessed the response of 11 plant traits to repeated experimental droughts in four co-occurring species of central Australia. The main goals of this study were to: (i) compare the response to drought between species; (ii) evaluate whether plants acclimated to repeated drought; and (iii) examine the degree of recovery in leaf gas exchange after cessation of drought. Our four species of study were two tree species and two shrub species, which field studies have shown to occupy different ecohydrological niches. The two tree species (Eucalyptus camaldulensis Dehnh. and Corymbia opaca (D.J.Carr & S.G.M.Carr) K.D.Hill & L.A.S.Johnson) had large reductions in stomatal conductance (gs) values, declining by 90% in the second drought. By contrast, the shrub species (Acacia aptaneura Maslin & J.E.Reid and Hakea macrocarpa A.Cunn. ex R.Br.) had smaller reductions gs in the second drought of 52 and 65%, respectively. Only A. aptaneura showed a physiological acclimatation to drought due to small declines in gs versus á´ªpd (0.08 slope) during repeated droughts, meaning they maintained higher rates of gs compared with plants that only experienced one final drought (0.19 slope). All species in all treatments rapidly recovered leaf gas exchange and leaf mass per area following drought, displaying physiological plasticity to drought exposure. This research refines our understanding of plant physiological responses to recurrent water stress, which has implications for modelling of vegetation, carbon assimilation and water use in semi-arid environments under drought.
Assuntos
Secas , Folhas de Planta , Árvores , Folhas de Planta/fisiologia , Árvores/fisiologia , Austrália , Transpiração Vegetal/fisiologia , Especificidade da Espécie , Aclimatação/fisiologiaRESUMO
Ongoing climate changes are expected to intensify drought periods in tropical regions, directly impacting epiphytic bromeliads that depend on intermittent water availability. This study aimed to elucidate if Acanthostachys pitcairnioides, an epiphytic bromeliad of Atlantic Forest, tolerates extended drought periods and the potential strategies involved in its tolerance and recovery capacity. We suppressed irrigation for 42 days, rehydrated plants for four days, and evaluated leaf water status, and photochemical, metabolic, and anatomical changes. During the initial 28 days of drought, translocation of water from hydrenchyma to chlorenchyma, higher chlorophyll content, and accumulation of abscisic and salicylic acid and antioxidants contributed to maintaining the cell turgor and functionality of photosynthetic apparatus. At 42 days, a significant reduction in leaf water content to 45.5% was accompanied by a 2.5-fold increase in non-photochemical quenching and enhanced levels of carotenoids, anthocyanins, osmoregulators (proline, myo-inositol, and trehalose), and phytohormones (abscisic acid and jasmonates). After rewatering, water storage in the hydrenchyma and almost all pigments, hormones, and metabolites were restored to pre-stress conditions. Leaf succulence, carbohydrate and organic acid accumulation, and carbon isotope data (δ13C-14.5) provide evidence of induction of CAM metabolism by water limitation in A. pitcairnioides. Our findings indicate the prevalence of water accumulation strategy during the first half of the drought stress. At the end of the drought period, the complete depletion of water from the hydrenchyma favored the osmotic adjustment. Considering this set of tolerance strategies and the rapid recovery after rehydration, A. pitcairnioides can successfully withstand environments with restricted water availability.
Assuntos
Bromeliaceae , Secas , Bromeliaceae/metabolismo , Bromeliaceae/fisiologia , Folhas de Planta/metabolismo , Adaptação Fisiológica , Água/metabolismo , Fotossíntese/fisiologia , Clorofila/metabolismo , Ácido Abscísico/metabolismoRESUMO
Oil palm (Elaeis guineensis Jacq.) is a highly productive crop economically significant for food, cosmetics, and biofuels. Abiotic stresses such as low water availability, salt accumulation, and high temperatures severely impact oil palm growth, physiology, and yield by restricting water flux among soil, plants, and the environment. While drought stress's physiological and biochemical effects on oil palm have been extensively studied, the molecular mechanisms underlying drought stress tolerance remain unclear. Under water deficit conditions, this study investigates two commercial E. guineensis cultivars, IRHO 7001 and IRHO 2501. Water deficit adversely affected the physiology of both cultivars, with IRHO 2501 being more severely impacted. After several days of water deficit, there was a 40% reduction in photosynthetic rate (A) for IRHO 7001 and a 58% decrease in IRHO 2501. Further into the drought conditions, there was a 75% reduction in A for IRHO 7001 and a 91% drop in IRHO 2501. Both cultivars reacted to the drought stress conditions by closing stomata and reducing the transpiration rate. Despite these differences, no significant variations were observed between the cultivars in stomatal conductance, transpiration, or instantaneous leaf-level water use efficiency. This indicates that IRHO 7001 is more tolerant to drought stress than IRHO 2501. A differential gene expression and network analysis was conducted to elucidate the differential responses of the cultivars. The DESeq2 algorithm identified 502 differentially expressed genes (DEGs). The gene coexpression network for IRHO 7001 comprised 274 DEGs and 46 predicted HUB genes, whereas IRHO 2501's network included 249 DEGs and 3 HUB genes. RT-qPCR validation of 15 DEGs confirmed the RNA-Seq data. The transcriptomic profiles and gene coexpression network analysis revealed a set of DEGs and HUB genes associated with regulatory and transcriptional functions. Notably, the zinc finger protein ZAT11 and linoleate 13S-lipoxygenase 2-1 (LOX2.1) were overexpressed in IRHO 2501 but under-expressed in IRHO 7001. Additionally, phytohormone crosstalk was identified as a central component in the response and adaptation of oil palm to drought stress.