Search Results (68)

The structure and diversity of tropical vegetation are shaped by biotic and abiotic factors, which function as environmental filters affecting plant performance on different spatial and temporal scales. We compared soil (Ferrasols and Cambisols) conditions, vegetation structure and leaf traits (e.g., specific leaf area, polyphenols, and chlorophyll contents a/b and in total) in the early, intermediate and late successional stages of a tropical dry forest (TDF) in southeastern Brazil. For this purpose, we measured leaf traits of the most abundant species in the same 18 plots (50 × 20 m/six per successional stage) in 2009 and 2018. Our prediction is that tree species growing in early forests have a greater investment in conservative traits related to chemical defenses and tolerance to desiccation compared to late-stage tree species. We observed contrasting results when comparing the chronosequence differences in leaf traits both in 2009 and 2018 and the temporal changes along this period. Specific leaf area was lower than expected for all successional stages, while polyphenol content increased over time, contrary to other studies in TDFs. These results suggest that contrasting environmental factors such as soil conditions and light availability are responsible of the observed pattern. Total chlorophyll content did not change significantly, while the a/b chlorophyll ratio doubled in all successional stages, contrary to our prediction. Therefore, we suggest that the conservative–acquisitive spectrum in successional gradients of TDFs should be further investigated with time-series data for a better understanding of plant community assemblages. Full article

The endogenous stress metabolite β-aminobutyric acid (BABA) primes plants for enhanced resistance against abiotic and biotic stress by activating a complex phytohormone signaling network that includes abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and ethylene (ET). In this study, through stringent filtering, we identify 14 master regulatory transcription factors (TFs) from the DOF, AHL, and ERF families that potentially regulate the biosynthesis and signaling of these phytohormones. Transcriptional analysis of BABA-treated Arabidopsis thaliana and Hordeum vulgare suggests that DOF family TFs play a crucial role in stress response regulation in both species. BABA treatment in A. thaliana upregulates the TFs MNB1A and PBF and enhances the expression of the genes ICS1, EDS5, and WIN3 in the SA biosynthesis pathway, potentially boosting NPR1 and PR1 in the SA signaling pathway. Conversely, in H. vulgare, the BABA-induced upregulation of TF DOF5.8 may negatively regulate SA biosynthesis by downregulating ICS1, EDS5, and PR1. Additionally, in A. thaliana, BABA triggers the expression of TF PBF, which may result in the decreased expression of MYC2, a key gene in JA signaling. In contrast, H. vulgare exhibits increased expression of ERF2 TF, which could positively regulate the JA biosynthesis genes LOX and Tify9, along with the COI1 and JAZ genes involved in the JA signaling pathway. These findings offer new perspectives on the transcriptional regulation of phytohormones during plant priming. Full article

The environmental filtering hypothesis predicts that abiotic factors restrict communities by selecting species capable of survival and persistence under specific conditions, resulting in variations in beta diversity, phylogenetic clustering, and niche differentiation among communities when studying environmental gradients. Cushion bogs and high-altitude wetlands along the Andes display homogeneous flora contrasting with zonal vegetation. Despite being influenced by microclimatic conditions, these ecosystems are subject to diverse environmental effects. Here, we test the environmental filtering hypothesis on the structure of cushion bog communities along a broad-scale latitudinal gradient from 15° S to 42° S. We analyzed 421 bogs and 293 species across three macroclimatic regions with distinct summer, winter, and transitional arid rainfall regimes. Using variance partitioning and membership-based regionalization models, we examined the impacts of climatic, edaphic, and spatial variables on beta diversity. We also assessed species’ niche overlap and the influence of environmental filters on the communities’ phylogenetic diversity. Results show that species turnover and niche overlap vary with macroclimatic differences, delineating three distinct regions. Notably, phylogenetic clustering in the driest part of the gradient (23° S–24° S) highlights the impact of environmental filtering. Aridity and temperature variations at a broad scale serve as environmental filters shaping the composition of bog communities across southern South America. Full article

We evaluated the main environmental factors (abiotic and biotic) driving the phytoplankton community in a shallow tropical reservoir located in an environmentally protected area. Phytoplankton samples were collected from the surface and bottom of the reservoir. The phytoplankton samples were later identified at the species level, and the species were further assigned to morphology-based functional groups (MBFGs). Zooplankton were sampled through vertical haul, communities were identified to species level, and functional diversity was estimated based on community-weighted means (CWM). Phytoplankton MBFGs IV, V, and VI contributed the most to the biomass under high light availability coupled with low nutrient availability. Potentially toxic cyanobacteria from MBFG III were observed during thermal stratification. Hydraulic mixing plays a crucial role in reducing the phytoplankton biomass during the warmer/rainy season. Cyclopoid copepods accounted for more than 83% of the zooplankton biomass. There was a weak but significant effect of zooplankton functional diversity on phytoplankton functional diversity, mainly because of the dominance of small zooplankton. Altogether, our findings suggest that environmental filtering plays a greater role than zooplankton grazing in phytoplankton community structure in this shallow tropical reservoir. Full article

Urban air pollution is a crucial global challenge, mainly originating from urbanization and industrial activities, which are continuously increasing. Vegetation serves as a natural air filter for air pollution, but adverse effects on plant health, photosynthesis, and metabolism can occur. Recent omics technologies have revolutionized the study of molecular plant responses to air pollution, overcoming previous limitations. This review synthesizes the latest advancements in molecular plant responses to major air pollutants, emphasizing ozone (O₃), nitrogen oxides (NO_X), and particulate matter (PM) research. These pollutants induce stress responses common to other abiotic and biotic stresses, including the activation of reactive oxygen species (ROSs)-scavenging enzymes and hormone signaling pathways. New evidence has shown the central role of antioxidant phenolic compound biosynthesis, via the phenylpropanoid pathway, in air pollution stress responses. Transcription factors like WRKY, AP2/ERF, and MYB, which connect hormone signaling to antioxidant biosynthesis, were also affected. To date, research has predominantly focused on laboratory studies analyzing individual pollutants. This review highlights the need for comprehensive field studies and the identification of molecular tolerance traits, which are crucial for the identification of tolerant plant species, aimed at the development of sustainable nature-based solutions (NBSs) to mitigate urban air pollution. Full article

Fire in the Northern Alps is comparatively rare. Yet, previous human-ignited fire events in subalpine forests up to the treeline have triggered severe fire damage to vegetation and soil. Here, we investigate post-fire vegetation dynamics in the Northern Limestone Alps about 80 years after disturbance. We observed higher species richness in burned compared to unburned vegetation and clearly distinct floristic communities emerging after fire-driven forest removal, with several alpine specialist species uniquely found in the burned subalpine sites. The functional composition of vegetation was also distinct, with higher relative forb cover in burned plots. This difference was likely driven by disturbance-related environmental changes, such as increased light availability, offering safe sites for subalpine and alpine species. Due to a general lack of tree encroachment, we consider this a case of arrested succession after fire. We conclude that the recovery of fire-affected subalpine forests is modulated by complex interactions of climatic and biotic filters producing extreme site conditions, controlling the recolonization of the disturbed areas by forest species while providing safe sites for the establishment of a rich subalpine and alpine low-statured flora. The coupling of disturbance and abiotic filters makes high-elevation treeline ecotones very vulnerable to climate change. Full article

Biosand reactors (BSRs), alternatively known as slow or biological sand filters, are passive systems that are used to remove contaminants from domestic wastewater, industrial wastewater and drinking water. This review focuses specifically on their application for remediation of industrial effluent and sewage-containing municipal and household effluent. The relationships between the physicochemical characteristics of the sand grains (size, size distribution, shape, chemical composition) and the hydraulic conductivity of the sand employed in BSFs are critically discussed in relationship to the achievable loading rates and hydraulic retention times. The modes of operation and influence of the functional microbial biomass as well as biodegradable and recalcitrant particulates on these parameters is comprehensively reviewed. Finally, the bioremediation of sewage-based and industrial wastewater is examined. This includes an account of the biotic and abiotic removal mechanisms and the limitations of BSRs for removal of pollutants such as phosphorus/phosphate and nitrates/nitrites. The removal mechanisms and removal efficiencies of macronutrients, micropollutants, fecal indicators and other microorganisms such as antibiotic-resistant bacteria in BSRs are discussed. Full article

Understanding the process underlying species coexistence is crucial in ecology. This challenge is relevant in tree communities inhabiting contrasting abiotic conditions, such as lowland floodplain and shallow hillslope karstic systems. We examined the influence of topographic variables and spatial factors on the structure of tree communities in the karstic system in Calakmul, Mexico. We measured 7050 trees (diameter at breast height ≥ 3 cm) in 152 circular plots and generated seven topographic variables from a digital elevation model. We employed redundancy analysis and variance partitioning to test the effects of environmental and spatial factors on tree communities. In addition, we used the null Raup–Crick model to uncover the relative importance of the deterministic and stochastic processes driving community assembly. Our study revealed significant floristic distinction between seasonally flooded and upland forests. The topographic wetness index (TWI) contribution to explaining the floristic differentiation in the studied tree assemblages was greater than that of the other topography-related variables. The explanatory power of the environmental and spatial factors varied slightly between datasets. The null model indicated a predominant influence of deterministic over stochastic processes. Our findings reaffirm the role of seasonal flooding as an abiotic filter. Additionally, the TWI can serve to identify flood-prone conditions within shallow depressions. The preservation of adjacent seasonally flooded and upland forests is relevant for the maintenance of tree diversity in the karst of the Yucatan Peninsula, since flooding drives the distribution of species. Full article

A hybrid desulfurization process combining a physical filtration stage on cellular concrete (CC abiotic filter, called CCAF) and a biotrickling filter (called BTF) filled with expanded schist as packing material was used to remove high H₂S concentrations from a synthetic gas containing dinitrogen (N₂), dioxygen (O₂) and H₂S without the addition of a nutritive solution. Provided that small amounts of oxygen are present in the gas (1.2 ± 0.1% in volume), the global removal efficiency was 100%, and the global removal capacity reached 35 ± 2 gH₂S m⁻³ h⁻¹ for a total empty bed residence time (EBRT) of 120 s (CCAF + BTF). The resilience of the desulfurization process was demonstrated by applying severe changes in the H₂S concentrations, from 160 to 1150 ± 20 mg m⁻³ for an EBRT = 120 s. According to the performances of the abiotic filter, which can decline over time due to the lifetime of the cellular concrete (137 days), the biotrickling filter reacted either as a refining system or as an efficient system able to treat significant H₂S loading rates (up to 45 ± 3 gH₂S m⁻³ h⁻¹). Depending on the operating conditions, the increase in the pressure drops of the biotrickling filter (from 45 ± 3 to 234 ± 8 Pa m⁻¹) highlighted biomass accumulation, especially extremophilic Acidithiobacillus sp. Considering the cellular concrete abiotic filter alone, removal capacities of up to 56 ± 3 gH₂S m⁻³ h⁻¹ were recorded for an EBRT of 60 s, demonstrating that gases such as landfill biogas or household biogas could be efficiently treated using this simple technique. Full article

Inputs of carbon (C) and nutrients from organic residues may select specific microbes and shape the soil microbial community. However, little is known about the abiotic filtering of the same residues with different nutrient concentrations applied to the soil. In our study, we explored how applying organic residue, vinasse, as fertilizer in its natural state (V) versus its concentrated form (CV) impacts soil microbiota. We conducted two field experiments, evaluating soil prokaryotic and fungal communities over 24 and 45 days with vinasse (V or CV) plus N fertilizer. We used 16S rRNA gene and ITS amplicon sequencing. Inorganic N had no significant impact on bacterial and fungal diversity compared to the control. However, the varying concentrations of organic C and nutrients in vinasse significantly influenced the soil microbiome structure, with smaller effects observed for V compared to CV. Prokaryotic and fungal communities were not correlated (co-inertia: RV coefficient = 0.1517, p = 0.9708). Vinasse did not change the total bacterial but increased the total fungal abundance. A higher C input enhanced the prokaryotic but reduced the fungal diversity. Our findings highlight vinasse’s role as an abiotic filter shaping soil microbial communities, with distinct effects on prokaryotic and fungal communities. Vinasse primarily selects fast-growing microorganisms, shedding light on the intricate dynamics between organic residues, nutrient concentrations, and soil microbes. Full article

Disturbances have created heterogeneous habitats for secondary and old-growth forests. Under the assumption that ecologically similar species have similar functional traits, numerous studies have attempted to use trait-based approaches to infer the abiotic and biotic factors that drive variations in community composition across different forests. However, the relative importance of these drivers in monsoon forests remains poorly understood. In this study, we randomly selected 86 plots and classified them into three forest types according to environmental factors: 1—secondary forests: secondary forest habitats at high elevation; 2—ecotone forests: general recovery and elevation; and 3—old growth forests: old growth at low elevations. We then compared the species and six leaf functional trait variations across the three forests and assessed their relationships with 15 environmental factors. The results showed that secondary and ecotone forests with a conservative strategy, exhibiting high dry matter content and leaf carbon content, tended to persist in stressful habitats, such as nutrient-poor soil, whereas old growth forests invested in trait values related to rapid resource acquisition with high specific leaf area, leaf nitrogen content, leaf phosphorous content, and leaf potassium content. Species with functional trait values between the secondary, ecotone, and old growth forests had clear signatures of their different strategies to persist in assemblages under distinct and opposite environmental filters. These plots were classified into three forest types according to environmental factors: (1) secondary forest at high elevation; (2) ecotone forests at general elevation; and (3) old growth forests at low elevation. Recovery time and elevation, followed by soil nutrients and light capture, were the most important factors shaping species and functional trait variations across forests. These results have demonstrated that environmental filters select plant species with distinct traits and ecological strategies. Acquisitive traits indicate higher competitive ability and faster resource acquisition for forest species that occur in areas with high soil fertility. Meanwhile, conservative traits promote the resistance of secondary species to environmental stressors in low soil fertility, suggesting that analyzing leaf functional-based trait variations to understand plant ecological strategies along an environmental gradient may improve understanding of forest dynamics in tropical monsoon forests. Full article

Abaca (Musa textilis Née) is an economically important fiber crop in the Philippines. Its economic potential, however, is hampered by biotic and abiotic stresses, which are exacerbated by insufficient genomic resources for varietal identification vital for crop improvement. To address these gaps, this study aimed to discover genome-wide polymorphisms among abaca cultivars and other Musa species and analyze their potential as genetic marker resources. This was achieved through whole-genome Illumina resequencing of abaca cultivars and variant calling using BCFtools, followed by genetic diversity and phylogenetic analyses. A total of 20,590,381 high-quality single-nucleotide polymorphisms (SNP) and DNA insertions/deletions (InDels) were mined across 16 abaca cultivars. Filtering based on linkage disequilibrium (LD) yielded 130,768 SNPs and 13,620 InDels, accounting for 0.396 ± 0.106 and 0.431 ± 0.111 of gene diversity across these cultivars. LD-pruned polymorphisms across abaca, M. troglodytarum, M. acuminata and M. balbisiana enabled genetic differentiation within abaca and across the four Musa spp. Phylogenetic analysis revealed the registered varieties Abuab and Inosa to accumulate a significant number of mutations, eliciting further studies linking mutations to their advantageous phenotypes. Overall, this study pioneered in producing marker resources in abaca based on genome-wide polymorphisms vital for varietal authentication and comparative genotyping with the more studied Musa spp. Full article

Plant pectin methylesterases (PMEs) play crucial roles in regulating cell wall modification and response to various stresses. Members of the PME family have been found in several crops, but there is a lack of research into their presence in cassava (Manihot esculent), which is an important crop for world food security. In this research, 89 MePME genes were identified in cassava that were separated into two types (type-Ⅰ and type-Ⅱ) according to the existence or absence of a pro-region (PMEI domain). The MePME gene members were unevenly located on 17 chromosomes, with 19 gene pairs being identified that most likely arose via duplication events. The MePMEs could be divided into ten sub-groups in type-Ⅰ and five sub-groups in type-Ⅱ. The motif analysis revealed 11 conserved motifs in type-Ⅰ and 8 in type-Ⅱ MePMEs. The number of introns in the CDS region of type-Ⅰ MePMEs ranged between one and two, and the number of introns in type-Ⅱ MePMEs ranged between one and nine. There were 21 type-Ⅰ and 31 type-Ⅱ MePMEs that contained signal peptides. Most of the type-Ⅰ MePMEs had two conserved “RK/RLL” and one “FPSWVS” domain between the pro-region and the PME domain. Multiple stress-, hormone- and tissue-specific-related cis-acting regulatory elements were identified in the promoter regions of MePME genes. A total of five co-expressed genes (MePME1, MePME2, MePME27, MePME65 and MePME82) were filtered from different abiotic stresses via the use of UpSet Venn diagrams. The gene expression pattern analysis revealed that the expression of MePME1 was positively correlated with the degree of cassava postharvest physiological deterioration (PPD). The expression of this gene was also significantly upregulated by 7% PEG and 14 °C low-temperature stress, but slightly downregulated by ABA treatment. The tissue-specific expression analysis revealed that MePME1 and MePME65 generally displayed higher expression levels in most tissues than the other co-expressed genes. In this study, we obtain an in-depth understanding of the cassava PME gene family, suggesting that MePME1 could be a candidate gene associated with multiple abiotic tolerance. Full article

Due to stricter municipal wastewater discharge standards, there is an increased need for further treatment of nitrate in the secondary effluent of wastewater treatment plants. This is achieved through denitrification by the addition of external carbon sources, which leads to increased costs in wastewater treatment. The aim of this study was to examine the possibility of simultaneous removal of nitrate and phosphorus from simulated secondary effluent by employing a sponge-iron-based denitrifying filter at room temperature. The results indicate that at hydraulic retention times of over 2 h, more than 60% of the nitrate was reduced to ammonia and nitrite via iron-based abiotic nitrate reduction. However, sponge iron easily scaled after two months of operation. Therefore, a little glucose was added to the influent, resulting in a final COD/N ratio of 1:1. Mixotrophic nitrate reduction was observed, and the rust of sponge iron was successfully dissolved. Batch test results demonstrate that biological nitrate denitrification accounted for 70.0% of the total nitrate reduction. Additionally, high-efficiency phosphorus removal through the chemical reaction of released iron and phosphorus was achieved throughout the entire experiment, with removal efficiencies of more than 90% at hydraulic retention times of over 2 h. Moreover, high-throughput sequencing data show that the species diversity obviously increased after adding organic carbon, suggesting the coexistence of heterotrophic and autotrophic denitrifiers. Hence, the sponge-iron denitrifying filter has considerable prospects in the field of secondary effluent treatment and is likely to be the future direction of zero-valent iron application in sewage treatment. Full article

Investigating functional plant traits is essential for understanding plant responses and adaptations to global climate change and ecosystem functions. Synchronous observations of multiple plant traits across multiple sites are rare. Here, we obtained community, functional trait, and environmental data for different forest vegetation types in China’s tropical, subtropical, warm-temperate, and cold-temperate zones. Using principal component (PC) analysis, we constructed a composite–habitat gradient axis of biotic and abiotic factors across different climatic zones, differentiated functional trait compositions along the axis and their driving factors, and reached three main conclusions. (1) At the community level, the community-weighted mean and variance of each trait level differed across the climatic zones. Specific leaf areas and leaf phosphorus contents decreased with increasing PC1 values, whereas community-weighted means and variances of leaf dry-matter contents, leaf nitrogen-to-phosphorus ratios, and wood densities significantly increased with increasing PC1 values. However, the leaf nitrogen content varied along the PC1 axis. Both the community-weighted skewness and kurtosis of functional traits increased significantly with increasing PC1 values for the composite habitat gradient across the climatic zones. (2) The weighted mean, variance, skewness, and kurtosis of each functional trait exhibited different patterns on the composite habitat gradient PC2 axis than on the PC1 axis across the climatic zones, and the correlation was weak. (3) Most functional traits correlated significantly with the community-weighted mean and variance, kurtosis, and skewness. Therefore, the different functional trait compositions of forest communities in different climatic zones reflected trait convergence caused by the environment and trait differences caused by species competition in response to local-scale filtering. Full article