I. II. III. IV. V. VI. References SUMMARY: For survival, plants have to efficiently adjust their phenotype to environmental challenges, finely coordinating their responses to balance growth and ...defence. Such phenotypic plasticity can be modulated by their associated microbiota. The widespread mycorrhizal symbioses modify plant responses to external stimuli, generally improving the resilience of the symbiotic system to environmental stresses. Phytohormones, central regulators of plant development and immunity, are instrumental in orchestrating plant responses to the fluctuating environment, but also in the regulation of mycorrhizal symbioses. Exciting advances in the molecular regulation of phytohormone signalling are providing mechanistic insights into how plants coordinate their responses to environmental cues and mycorrhizal functioning. Here, we summarize how these mechanisms permit the fine‐tuning of the symbiosis according to the ever‐changing environment.
Honey bee decline is currently one of the world's most serious environmental issues, and scientists, governments, and producers have generated interest in understanding its causes and consequences in ...honey production and food supply. Mexico is one of the world's top honey producers, however, the honey bee population's status has not been documented to date. Based on 32 years of data from beekeeping, we make a country-level assessment of honey bee colony trends in Mexico. We use generalized additive mixed models to measure the associations between the percent change in honey bee hives and the percent change in honey yield per hive in relation to land-use, climate, and socioeconomic conditions. Despite the fact that the average annual yield per hive increased from 1980 to 2012, we detected a significant decline in the percent change in the number of honey bee hives across the time period studied. We also found a relationship between climatic conditions and agricultural land use, with agriculture increases and high temperatures producing a decrease in the percent change in honey yield. We found a relationship between a reduction in the temperature range (the difference between maximum and minimum temperatures) and a decrease in the percent change in the number of hives, while socioeconomic factors related to poverty levels have an impact on the number of hives and honey yields. Although long-term declines in hive numbers are not correlated with poverty levels, socioeconomic factors in states with high and medium poverty levels limit the increase in honey yield per hive. These results provide evidence that land-use changes, unfavorable climatic conditions, political, and socioeconomic factors are partially responsible for the reductions in the percent change in honey bee hives in Mexico.
Plant‐pollinator interactions are fundamental to ecosystem functioning; however, the role that succession and phenology have on these interactions is poorly understood, particularly in endangered ...tropical ecosystems. In highly diverse ecosystems such as tropical dry forests (TDF), variation in water and food availability determines the life cycles of animal pollinators. Therefore, understanding patterns of flowering phenology and plant‐pollinator interactions across seasons in successional environments is key to maintaining and restoring TDF.
We analysed the functional dynamics of plant‐floral visitor interactions at the community level across a successional gradient in a Mexican TDF. We evaluated changes in the diversity of blooming plant species and floral visitors, phenological patterns, interaction network metrics and beta diversity among early, intermediate and late successional stages, between dry and rainy seasons.
We found a higher diversity of blooming plant species and a higher richness of animal species in the intermediate and late successional stages. Peak abundance of floral visitors overlapped with flowering peaks in the late successional stages, but this was not consistently the case in the early and intermediate stages. Plant‐floral visitors networks differed in structure according to successional stage and season, but specialisation metrics were higher in late successional stages. Interaction networks were more dissimilar between dry and rainy seasons within successional stages than within seasons between successional stages, suggesting connectivity across successional sites during each season. In addition, closely related plant species do not share the same pollination systems in any successional stage.
Synthesis. Our results showed that plant‐floral visitor interactions are dynamic and vary with flowering phenology and with successional changes in plant and animal diversity. Plant‐floral visitor interactions were more diverse and specialised in the late successional stages. In the rainy season, differences in network structure among successional stages are due to interaction rewiring, while in the dry season, it is caused by species turnover. Our results demonstrate that seasonality plays a key role in community diversity and network structure and highlight the importance of conserving mature forests to ensure the maintenance of critical pollination interactions across all successional stages.
Resumen
Las interacciones planta‐polinizador son fundamentales para el funcionamiento del ecosistema; sin embargo, el papel que tienen la sucesión y la fenología en estas interacciones es poco conocido, particularmente en los ecosistemas tropicales. En ecosistemas amenazados y muy diversos, como los bosques tropicales secos (TDF), la variación en la disponibilidad de agua y recursos determina los ciclos de vida de los animales polinizadores. Por lo tanto, comprender los patrones de la fenología de floración y las interacciones planta‐polinizador en ambientes sucesionales a lo largo del año es clave para mantener y restaurar el TDF.
En este estudio, analizamos la dinámica funcional de las interacciones planta‐visitante floral a nivel de comunidad a través de un gradiente sucesional en un TDF mexicano. Evaluamos los cambios temporales en la abundancia y diversidad de las plantas en floración y los visitantes florales, así como los patrones fenológicos y las métricas de redes de interacción, y la diversidad beta entre etapas de sucesión tempranas, intermedias y tardías.
Encontramos una mayor diversidad de especies de plantas en floración y una mayor riqueza de especies animales en las etapas de sucesión intermedias y tardías. Los picos de floración y la abundancia de los visitantes florales traslapan en los estadíos tardíos de sucesión, pero no en los tempranos e intermedios. Las redes de interacción plantas‐visitante floral difieren en estructura de acuerdo con la etapa de sucesión y la estación del año, pero la especialización es más alta en los estadíos sucesionales tardíos. Las redes de interacción difieren más entre las estaciones seca y lluviosa dentro de cada estadío de sucesión, que entre estadíos sucesionales en cada estación, lo que sugiere conectividad entre los sitios sucesionales. También encontramos que en todas las etapas de sucesión, las especies de plantas estrechamente relacionadas no comparten los mismos sistemas de polinización.
Síntesis. Nuestros resultados muestran que las interacciones planta‐visitante floral son dinámicas y varían con la fenología de la floración y con los cambios sucesionales en la diversidad de plantas y animales. Las interacciones entre plantas y visitantes fueron más diversas y especializadas en las etapas tardías de sucesión. En la estación lluviosa, las diferencias en la estructura de la red entre las etapas sucesionales se deben predominantemente al recableado en las interacciones, mientras que en la estación seca se deben al recambio de especies. Nuestros resultados demuestran que la estacionalidad juega un papel clave en la determinación de la diversidad de la comunidad y la estructura de las redes, y destaca la importancia de conservar los bosques maduros para asegurar el mantenimiento de las interacciones de polinización durante la sucesión ecológica.
Our results showed that plant‐floral visitor interactions are dynamic and vary with flowering phenology and with successional changes in plant and animal diversity. Plant‐floral visitor interactions were more diverse and specialised in the late successional stages. In the rainy season, differences in network structure among successional stages are due to interaction rewiring, while in the dry season, they are caused by species turnover. Our results demonstrate that seasonality plays a key role in community diversity and network structure and highlight the importance of conserving mature forests to ensure the maintenance of critical pollination interactions across all successional stages.
Unraveling mycorrhiza-induced resistance Pozo, María J; Azcón-Aguilar, Concepción
Current opinion in plant biology,
08/2007, Letnik:
10, Številka:
4
Journal Article
Recenzirano
Arbuscular mycorrhizal symbioses have a significant impact on plant interactions with other organisms. Increased resistance to soil-borne pathogens has been widely described in mycorrhizal plants. By ...contrast, effects on shoot diseases largely rely on the lifestyle and challenge strategy of the attacker. Among the potential mechanisms involved in the resistance of mycorrhizal systems, the induction of plant defenses is the most controversial. During mycorrhiza formation, modulation of plant defense responses occurs, potentially through cross-talk between salicylic acid and jasmonate dependent signaling pathways. This modulation may impact plant responses to potential enemies by priming the tissues for a more efficient activation of defense mechanisms.
Arbuscular mycorrhizal (AM) symbioses are mutualistic associations between soil fungi and most vascular plants. The symbiosis significantly affects the host physiology in terms of nutrition and ...stress resistance. Despite the lack of host range specificity of the interaction, functional diversity between AM fungal species exists. The interaction is finely regulated according to plant and fungal characters, and plant hormones are believed to orchestrate the modifications in the host plant. Using tomato as a model, an integrative analysis of the host response to different mycorrhizal fungi was performed combining multiple hormone determination and transcriptional profiling. Analysis of ethylene-, abscisic acid-, salicylic acid-, and jasmonate-related compounds evidenced common and divergent responses of tomato roots to Glomus mosseae and Glomus intraradices, two fungi differing in their colonization abilities and impact on the host. Both hormonal and transcriptional analyses revealed, among others, regulation of the oxylipin pathway during the AM symbiosis and point to a key regulatory role for jasmonates. In addition, the results suggest that specific responses to particular fungi underlie the differential impact of individual AM fungi on plant physiology, and particularly on its ability to cope with biotic stresses.
The decline of honey bee populations significantly impacts the human food supply due to poor pollination and yield decreases of essential crop species. Given the reduction of pollinators, research ...into critical landscape components, such as floral resource availability and land use change, might provide valuable information about the nutritional status and health of honey bee colonies. To address this issue, we examine the effects of landscape factors like agricultural area, urban area, and climatic factors, including maximum temperature, minimum temperature, relative humidity, and precipitation, on honey bee hive populations and nutritional health of 326 honey bee colonies across varying landscapes in Mexico. DNA metabarcoding facilitated the precise identification of pollen from 267 plant species, encompassing 243 genera and 80 families, revealing a primary herb‐based diet. Areas characterized by high landscape diversity exhibited greater pollen diversity within the colony. Conversely, colonies situated in regions with higher proportions of agricultural and urban landscapes demonstrated lower bee density. The maximum ambient temperature outside hives positively correlated with pollen diversity, aligning with a simultaneous decrease in bee density. Conversely, higher relative humidity positively influenced both the bee density of the colony and the diversity of foraged pollen. Our national‐level study investigated pollen dietary availability and colony size in different habitat types, latitudes, climatic conditions, and varied levels and types of disturbances. This effort was taken to gain a better insight into the mechanisms driving declines in honey bee populations. This study illustrates the need for more biodiverse agricultural landscapes, the preservation of diverse habitats, and the conservation of natural and semi‐natural spaces. These measures can help to improve the habitat quality of other bee species, as well as restore essential ecosystem processes, such as pollination and pest control.
This study investigates how landscape diversity and climatic factors affect the populations and nutritional health of honey bee colonies in Mexico. It was found that greater landscape diversity correlates with higher pollen diversity, while areas with more agriculture and urbanization show lower bee densities. The results underscore the importance of preserving diverse habitats to support bee health and, by extension, human food security.
Maternal overweight, obesity, and gestational diabetes (GD) have been negatively associated with offspring development. Further knowledge regarding metabolic and nutritional alterations in these ...mother and their offspring are warranted.
In an observational cohort study we included 331 pregnant women from Granada, Spain. The mothers were categorized into four groups according to BMI and their GD status; overweight (n:56), obese (n:64), GD (n:79), and healthy normal weight controls (n:132). We assessed maternal growth and nutritional biomarkers at 24 weeks (n = 269), 34 weeks (n = 310) and at delivery (n = 310) and the perinatal characteristics including cord blood biomarkers.
Obese and GD mothers had significantly lower weight gain during pregnancy and infant birth weight, waist circumference, and placental weight were higher in the obese group, including a significantly increased prevalence of macrosomia. Except for differences in markers of glucose metabolism (glucose, HbA1c, insulin and uric acid) we found at some measures that overweight and/or obese mothers had lower levels of transferrin saturation, hemoglobin, Vitamin B12 and folate and higher levels of C-reactive protein, erythrocyte sedimentation rate, ferritin, and cortisol. GD mothers had similar differences in hemoglobin and C-reactive protein but higher levels of folate. The latter was seen also in cord blood.
We identified several metabolic alterations in overweight, obese and GD mothers compared to controls. Together with the observed differences in infant anthropometrics, these may be important biomarkers in future research regarding the programming of health and disease in children.
The trial was registered at clinicaltrials.gov, identifier ( NCT01634464 ).
T lymphocytes are key players in adaptive immune responses through the recognition of peptide antigens through the T Cell Receptor (TCR). After TCR engagement, a signaling cascade is activated, ...leading to T cell activation, proliferation, and differentiation into effector cells. Delicate control of activation signals coupled to the TCR is needed to avoid uncontrolled immune responses involving T cells. It has been previously shown that mice deficient in the expression of the adaptor NTAL (Non-T cell activation linker), a molecule structurally and evolutionarily related to the transmembrane adaptor LAT (Linker for the Activation of T cells), develop an autoimmune syndrome characterized by the presence of autoantibodies and enlarged spleens. In the present work we intended to deepen investigation into the negative regulatory functions of the NTAL adaptor in T cells and its potential relationship with autoimmune disorders. For this purpose, in this work we used Jurkat cells as a T cell model, and we lentivirally transfected them to express the NTAL adaptor in order to analyze the effect on intracellular signals associated with the TCR. In addition, we analyzed the expression of NTAL in primary CD4+ T cells from healthy donors and Rheumatoid Arthritis (RA) patients. Our results showed that NTAL expression in Jurkat cells decreased calcium fluxes and PLC-γ1 activation upon stimulation through the TCR complex. Moreover, we showed that NTAL was also expressed in activated human CD4+ T cells, and that the increase of its expression was reduced in CD4+ T cells from RA patients. Our results, together with previous reports, suggest a relevant role for the NTAL adaptor as a negative regulator of early intracellular TCR signaling, with a potential implication in RA.
In the context of the alarming rise of infant obesity and its health implications, the present research aims to uncover disruptions in postprandial lipid metabolism and the composition of ...triglyceride-rich lipoproteins in obese adolescents. A double-blind, controlled clinical trial in the postprandial phase on 23 adolescents aged 12 to 16 years was carried out. Twelve participants were categorized as obese (BMI > 30 kg/m
and percentile > 95) and 11 as normal-weight (BMI = 20-25 kg/m
, percentile 5-85). Blood samples were collected after a 12-h overnight fast and postprandially after consumption of a standardized breakfast containing olive oil, tomato, bread, orange juice, and skimmed milk. Obese adolescents exhibited elevated triglyceride concentrations in both fasting and postprandial states and higher TG/apo-B48 ratios, indicating larger postprandial triglyceride-rich lipoprotein (TRL) particle size, which suggests impaired clearance. Obese subjects also exhibited higher n-6 PUFA concentrations, potentially linked to increased TRL hydrolysis and the release of pro-inflammatory adipokines. In contrast, TRL from normal-weight individuals showed higher concentrations of oleic acid and DHA (n-3 PUFA), with possible anti-inflammatory effects. The results indicate an interplay involving postprandial TRL metabolism and adipokines within the context of adolescent obesity, pointing to potential cardiovascular implications in the future.
Arbuscular mycorrhizal (AM) symbioses can improve plant tolerance to multiple stresses. We compared three AM fungi (AMF) from different genera, one of them isolated from a dry and saline environment, ...in terms of their ability to increase tomato tolerance to moderate or severe drought or salt stress. Plant physiological parameters and metabolic profiles were compared in order to find the molecular mechanisms underlying plant protection against stress.
Mycorrhizal growth response was determined, and ultrahigh-performance LC-MS was used to compare the metabolic profile of plants under the different treatments.
All AMF increased plant tolerance to stress, and the positive effects of the symbiosis were correlated with the severity of the stress. The AMF isolated from the stressful environment was the most effective in improving plant tolerance to salt stress. Differentially accumulated compounds were identified and the antistress properties of some of them were confirmed.
We demonstrate that AM symbioses increase plant metabolic plasticity to cope with stress. Some responses were common to all AMF tested, while others were specifically related to particular isolates. Important metabolism reprograming was evidenced upon salt stress, and we identified metabolic pathways and compounds differentially accumulated in mycorrhizas that may underlie their enhanced tolerance to stress.
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