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This paper reports upon the finding of Viola baoshanensis, a cadmium (Cd) hyperaccumulator through field survey and greenhouse experiments. Average Cd concentration in the shoots and roots of V baoshanensis growing on Baoshan lead/zinc mine in Hunan Province, China, was 1168 and 981 mg/kg, respectively, varying from 456 to 2310 mg/kg in the shoots, and from 233 to 1846 mg/kg in the roots. The ratio of Cd concentration in shoot to root (DW) and that in plant shoots to total concentration in surface soil was 1.32 and 2.38, respectively. Under nutrient solution culture, bio- mass (DW) of V. baoshanensis exposed to O-30 mg/L Cd in solution increased with Cd supply increasing and reached a maximum at 30 mg/L Cd. Further increase of Cd concentration (40, 50 mg/L) in solution significantly reduced biomass. Cd concentration in the shoots was positively correlated with Cd concentration in the culture medium. Cd concentration in the shoots reached 4825 mg/kg at 50 mg/L Cd solution. The ratio of Cd concentration of shoots to roots in V. baoshanensis was greater than 1 at all Cd treatments, with an average of 1.67 (1.14-2.22). The results indicate that V. baoshanensis is a Cd hyperaccumulator plant. [ABSTRACT FROM AUTHOR]

Summary Modern cultivated rice (Oryza sativa) typically experiences limited growth benefits from arbuscular mycorrhizal (AM) symbiosis. This could be due to the long‐term domestication of rice under favorable phosphorus conditions. However, there is limited understanding of whether and how the rice domestication has modified AM properties. This study compared AM properties between a collection of wild (Oryza rufipogon) and domesticated rice genotypes and investigated the mechanisms underlying their differences by analyzing physiological, genomic, transcriptomic, and metabolomic traits critical for AM symbiosis. The results revealed significantly lower mycorrhizal growth responses and colonization intensity in domesticated rice compared to wild rice, and this change of AM properties may be associated with the domestication modifications of plant phosphorus utilization efficiency at physiological and genomic levels. Domestication also resulted in a decrease in the activity of the mycorrhizal phosphorus acquisition pathway, which may be attributed to reduced mycorrhizal compatibility of rice roots by enhancing defense responses like root lignification and reducing carbon supply to AM fungi. In conclusion, rice domestication may have changed its AM properties by modifying P nutrition‐related traits and reducing symbiotic compatibility. This study offers new insights for improving AM properties in future rice breeding programs to enhance sustainable agricultural production. [ABSTRACT FROM AUTHOR]

Wastewater biotreatment systems harbor a rich diversity of microorganisms, and the effectiveness of biotreatment systems largely depends on the activity of these microorganisms. Specifically, viruses play a crucial role in altering microbial behavior and metabolic processes throughout their infection phases, an aspect that has recently attracted considerable interest. Two metagenomic approaches, viral‐like particle‐concentrated (VPC, representing free viral‐like particles) and non‐concentrated (NC, representing the cellular fraction), were employed to assess their efficacy in revealing virome characteristics, including taxonomy, diversity, host interactions, lifestyle, dynamics, and functional genes across processing units of three wastewater treatment plants (WWTPs). Our findings indicate that each approach offers unique insights into the viral community and functional composition. Their combined use proved effective in elucidating WWTP viromes. We identified nearly 50,000 viral contigs, with Cressdnaviricota and Uroviricota being the predominant phyla in the VPC and NC fractions, respectively. Notably, two pathogenic viral families, Asfarviridae and Adenoviridae, were commonly found in these WWTPs. We also observed significant differences in the viromes of WWTPs processing different types of wastewater. Additionally, various phage‐derived auxiliary metabolic genes (AMGs) were active at the RNA level, contributing to the metabolism of the microbial community, particularly in carbon, sulfur, and phosphorus cycling. Moreover, we identified 29 virus‐carried antibiotic resistance genes (ARGs) with potential for host transfer, highlighting the role of viruses in spreading ARGs in the environment. Overall, this study provides a detailed and integrated view of the virosphere in three WWTPs through the application of VPC and NC metagenomic approaches. Our findings enhance the understanding of viral communities, offering valuable insights for optimizing the operation and regulation of wastewater treatment systems. Highlights: This study comprehensively compared viral‐like particle‐concentrated (VPC) and non‐concentrated (NC) metagenomic approaches in virome investigation, highlighting their respective efficacies in detecting different viral communities and functional elements in wastewater treatment plants (WWTPs).Eukaryotic viruses belonging to Cressdnaviricota were the most prevalent in VPC metagenomes, while bacterial viruses belonging to Uroviricota were the most abundant in NC metagenomes.Diverse phage‐born auxiliary metabolic genes (AMGs) were discovered in the virome of WWTPs, and a large array of AMGs involved in biogeochemical cycles like carbon, sulfur, and phosphorus cycling showed transcriptional activation in wastewater treatment systems.A tiny proportion (less than 0.08% of viral operational taxonomic units) of viruses was discovered to harbor antibiotic resistance genes (ARGs) (29 phage‐born ARGs) only in the cellular fraction, and phage‐born ARG types primarily included macrolide–lincosamide–streptogramin, tetracycline, and aminoglycoside resistance. [ABSTRACT FROM AUTHOR]

Little is known about the relationships between human genetics and the airway microbiome. Deeply sequenced airway metagenomics, by simultaneously characterizing the microbiome and host genetics, provide a unique opportunity to assess the microbiome-host genetic associations. Here we performed a co-profiling of microbiome and host genetics with the identification of over 5 million single nucleotide polymorphisms (SNPs) through deep metagenomic sequencing in sputum of 99 chronic obstructive pulmonary disease (COPD) and 36 healthy individuals. Host genetic variation was the most significant factor associated with the microbiome except for geography and disease status, with its top 5 principal components accounting for 12.11% of the microbiome variability. Within COPD individuals, 113 SNPs mapped to candidate genes reported as genetically associated with COPD exhibited associations with 29 microbial species and 48 functional modules (P < 1 × 10−5), where Streptococcus salivarius exhibits the strongest association to SNP rs6917641 in TBC1D32 (P = 9.54 × 10−8). Integration of concurrent host transcriptomic data identified correlations between the expression of host genes and their genetically-linked microbiome features, including NUDT1, MAD1L1 and Veillonella parvula, TTLL9 and Stenotrophomonas maltophilia, and LTA4H and Haemophilus influenzae. Mendelian randomization analyses revealed a potential causal link between PARK7 expression and microbial type III secretion system, and a genetically-mediated association between COPD and increased relative abundance of airway Streptococcus intermedius. These results suggest a previously underappreciated role of host genetics in shaping the airway microbiome and provide fresh hypotheses for genetic-based host-microbiome interactions in COPD. [ABSTRACT FROM AUTHOR]

Global climate models predict that the frequency and intensity of precipitation events will increase in many regions across the world. However, the biosphere‐climate feedback to elevated precipitation (eP) remains elusive. Here, we report a study on one of the longest field experiments assessing the effects of eP, alone or in combination with other climate change drivers such as elevated CO2 (eCO2), warming and nitrogen deposition. Soil total carbon (C) decreased after a decade of eP treatment, while plant root production decreased after 2 years. To explain this asynchrony, we found that the relative abundances of fungal genes associated with chitin and protein degradation increased and were positively correlated with bacteriophage genes, suggesting a potential viral shunt in C degradation. In addition, eP increased the relative abundances of microbial stress tolerance genes, which are essential for coping with environmental stressors. Microbial responses to eP were phylogenetically conserved. The effects of eP on soil total C, root production, and microbes were interactively affected by eCO2. Collectively, we demonstrate that long‐term eP induces soil C loss, owing to changes in microbial community composition, functional traits, root production, and soil moisture. Our study unveils an important, previously unknown biosphere‐climate feedback in Mediterranean‐type water‐limited ecosystems, namely how eP induces soil C loss via microbe‐plant–soil interplay. [ABSTRACT FROM AUTHOR]

A total of 455 agricultural soil samples from four nonferrous mines/smelting sites in Shaoguan City, China, were investigated for concentrations of 10 heavy metals (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, and Zn). The mean concentrations of the metals were 72.4, 5.16, 13.3, 54.8, 84.5, 1.52, 425, 28.2, 529, and 722 mg kg−1, respectively. The values for As, Cd, Hg, Pb, and Zn were more than 8 and 1.5 times higher than their background values in this region and the limit values of Grade II soil quality standard in China, respectively. Estimated ecological risks based on contamination factors and potential ecological risk factors were also high or very high for As, Cd, Hg, and Pb. Multivariate analysis (Pearson's correlation analysis, hierarchical cluster analysis, and principal component analysis) strongly implied three distinct groups; i.e., As/Cu/Hg/Zn, Co/Cr/Mn/Ni, and Cd/Pb. Local anomalies for As, Cu, Hg, and Zn by a probably anthropogenic source (identified as mining activity), Co, Cr, Mn, and Ni by natural contribution, and a mixed source for Cd and Pb, were identified. This is one of the few studies with a focus on potential sources of heavy metals in agricultural topsoil around mining/smelting sites, providing evidence for establishing priorities in the reduction of ecological risks posed by heavy metals in Southern China and elsewhere. [ABSTRACT FROM PUBLISHER]

Understanding the influences of global climate change on soil microbial communities is essential in evaluating the terrestrial biosphere's feedback to this alarming anthropogenic disturbance. However, little is known about how intra‐site historical climate variability can mediate the influences of current climate differences on community dissimilarity and assembly. To fill this gap, we examined and disentangled the interactive effects of historical climate variability and current climate differences on the soil bacterial community dissimilarity and stochasticity of community assembly among 143 sites from 28 forests across eastern China. We hypothesize that the relative importance of stochasticity and community dissimilarity are related to historical climate variability and that an increasing sum of intra‐site historical variability enhances stochasticity while reduces dissimilarity between two communities. To test our hypothesis, we statistically controlled for covariates between sites including differences in soil chemistry, plant diversity, spatial distance, and seasonal climate variations at annual timescales. We observed that an increase in inter‐site current climate differences led to a reduced impact of stochasticity in community assembly and a pronounced divergence between communities. In stark contrast, when communities were subjected to a high level of intra‐site historical climate fluctuation, the observed impact incurred from current climate differences was substantially weakened. Moreover, the influence of increased historical variability was consistent along the gradient of current temperature differences between sites. However, effects induced by historical fluctuation in precipitation were disproportional and only evident when small inter‐site differences were observed. Consequently, if the prior climate variability is ignored, especially regarding environmental factors like temperature, we assert that the influence current climate differentiation has on regulating community dissimilarity and assembly stochasticity will be underestimated. Together, our findings highlight the importance and need of explicitly controlling the mean and the historical variability of climate factors for the next "generation" of climate change experiments to come. [ABSTRACT FROM AUTHOR]

A field study of Pb/Zn mine tailings was conducted to assess the influence of AM fungi and refuse compost on phytoremediation using vetiver grass slips. Our investigation revealed that vetiver could thrive on Pb/Zn mine tailings. The addition of refuse compost resulted in biomass that was more than 3-times higher when compared with the control, and were mainly attributed to an improvement of soil properties, as well as better nutrient supply than untreated control. AMF inoculation also significantly increased the dry matter of vetiver by a rate of 8.1-13.8%. It was observed that concentrations of N and P in the shoots were significantly higher in mycorrhizal treatments than those without AMF inoculation. However, AMF inoculation significantly decreased the metal concentrations in root, but not in shoot. Based on the results, it seems clear that AMF can play an essential role in the phytostabilization of metal contaminated soils. [ABSTRACT FROM AUTHOR]

Summary: The study of islands has made substantial contributions to the development of evolutionary and ecological theory. However, we know little about microbial community assembly on islands. Using soil microbial data collected from 29 lake islands and nearby mainland, we examined the assembly mechanisms of soil bacterial and fungal communities among and within islands. We found that deterministic processes, especially homogeneous selection, tended to be more important in shaping the assembly of soil bacterial communities among islands, while stochastic processes tended to be more important within islands. Moreover, increasing island area increased the importance of homogeneous selection, but reduced the importance of variable selection, for soil bacterial community assembly within islands. By contrast, stochastic processes tended to dominate soil fungal community assembly both among and within islands, with dispersal limitation playing a more important role within than among islands. Our results highlight the scale‐ and taxon‐dependence of insular soil microbial community assembly, suggesting that spatial scale should be explicitly considered when evaluating the influences of habitat fragmentation on soil microbial communities. [ABSTRACT FROM AUTHOR]

• The microbial network associations were strengthened along the AMD-impacted river. • Community assembly processes shifted from the headwaters to downstream. • Relative modularity was essential biotic factor in shaping community composition. Acid mine drainage (AMD) serves as an ideal model system for investigating microbial ecology, interaction, and assembly mechanism in natural environments. While previous studies have explored the structure and function of microbial communities in AMD, the succession patterns of microbial association networks and underlying assembly mechanisms during natural attenuation processes remain elusive. Here, we investigated prokaryotic microbial diversity and community assembly along an AMD-impacted river, from the extremely acidic, heavily polluted headwaters to the nearly neutral downstream sites. Microbial diversity was increased along the river, and microbial community composition shifted from acidophile-dominated to freshwater taxa-dominated communities. The complexity and relative modularity of the microbial networks were also increased, indicating greater network stability during succession. Deterministic processes, including abiotic selection of pH and high contents of sulfur and iron, governed community assembly in the headwaters. Although the stochasticity ratio was increased downstream, manganese content, microbial negative cohesion, and relative modularity played important roles in shaping microbial community structure. Overall, this study provides valuable insights into the ecological processes that govern microbial community succession in AMD-impacted riverine ecosystems. These findings have important implications for in-situ remediation of AMD contamination. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary: Soil plant‐pathogenic (PF) and mycorrhizal fungi (MF) are both important in maintaining plant diversity, for example via host‐specialized effects. However, empirical knowledge on the degree of host specificity and possible factors affecting the fungal assemblages is lacking.We identified PF and MF in fine roots of 519 individuals across 45 subtropical tree species in southern China in order to quantify the importance of host phylogeny (including via its effects on functional traits), habitat and space in determining fungal communities. We also compared host specificity in PF and MF at different host‐phylogenetic scales.In both PF and MF, host phylogeny independently accounted for > 19% of the variation in fungal richness and composition, whereas environmental and spatial factors each explained no more than 4% of the variation. Over 77% of the variation explained by phylogeny was attributable to covariation in plant functional traits. Host specificity was phylogenetically scale‐dependent, being stronger in PF than in MF at low host‐phylogenetic scales (e.g. within genus) but similar at larger scales.Our study suggests that host‐phylogenetic effects dominate the assembly of both PF and MF communities, resulting from phylogenetically clustered plant traits. The scale‐dependent host specificity implies that PF were specialized at lower‐level and MF at higher‐level host taxa. [ABSTRACT FROM AUTHOR]

One of the central questions in ecology is why some species are abundant while others are rare. In plant communities, some studies show that rare plant species are rare because they suffer stronger negative density‐dependent effects from pathogens compared to abundant plant species. Moreover, such pathogen effects are also suggested to be related to phylogenetic distance among plant species. However, the importance of pathogens has been commonly inferred by treating the entire pathogen community as a "black box" without explicitly characterizing pathogen richness and community composition.Here, we test two predictions. First, if rare plant species are more susceptible to pathogens, we predict that rare plant species are associated with a higher richness of specialists (i.e., pathogens that attack only a single plant species) and/or the total pathogen community. If phylogenetically distinct plant species are less susceptible to pathogens, we predict that plant species with higher phylogenetic distinctiveness (i.e., a measure of how phylogenetically distant a species is from other co‐occurring species) are associated with a lower richness of phylogenetic specialists (i.e., pathogens that attack closely related plant species) and/or the total pathogen community.We conducted a survey of the root‐associated pathogen communities from 45 plant species in a subtropical forest. We showed that approximately 40% and 25% of the pathogens were specialists and phylogenetic specialists respectively. In contrast to our first prediction, the richness of the total pathogen community but not the richness of the specialists was found to be positively related to plant species abundance, indicating that rare plant species suffer less from pathogens. Consistent with our second prediction, both the richness of the phylogenetic specialists and the total pathogen community were found to be negatively related to plant species phylogenetic distinctiveness. Furthermore, these correlations were stronger at the earlier plant life stages examined.Synthesis. We found that the root‐associated pathogen communities were less diverse in rare plant species and plant species with few close relatives. These associations varied across multiple plant life stages, suggesting that the strength of the above‐ground–below‐ground interactions change dynamically across plant life span. [ABSTRACT FROM AUTHOR]

Ecosystem function is the outcome of species interactions, traits, and niche overlap - all of which are influenced by evolution. However, it is not well understood how the tempo and mode of niche evolution can influence ecosystem function. In evolutionary models where either species differences accumulate through random drift in a single trait or species differences accumulate through divergent selection among close relatives, we should expect that ecosystem function is strongly related to diversity. However, when strong selection causes species to converge on specific niches or when novel traits that directly affect function evolve in some clades but not others, the relationship between diversity and ecosystem function might not be very strong. We test these ideas using a field experiment that established plant mixtures with differing phylogenetic diversities and we measured ten different community functions. We show that some functions were strongly predicted by species richness and mean pairwise phylogenetic distance ( MPD, a measure of phylogenetic diversity), including biomass production and the reduction of herbivore and pathogen damage in polyculture, while other functions had weaker (litter production and structural complexity) or nonsignificant relationships (e.g., flower production and arthropod abundance) with MPD and richness. However, these divergent results can be explained by different models of niche evolution. These results show that diversity-ecosystem function relationships are the product of evolution, but that the nature of how evolution influences ecosystem function is complex. [ABSTRACT FROM AUTHOR]

Microbial community assembly contributes to the restoration and rehabilitation of the disturbed ecosystems. However, the viral assembly mechanism and its difference from bacterial communities under soil contamination have not been previously reported. Here, clean, light and heavy chromium (Cr)-contaminated soils were collected from two Cr slag sites and adjacent soils in northwestern and southwestern China. Through metagenome and virome sequencing analysis, we found that the alpha diversity of bacterial genes (including overall genes and Cr detoxifying genes) showed no clear variance (p > 0.05) across soils, indicating the functional redundancy in the bacterial communities. The assembly of both the bacteria and virus taxa were primarily controlled by deterministic process across soils The assembly of bacterial genes turned from stochastic processes to deterministic processes when the Cr content increased in soils. By contrast, the assembly of viral genes altered from deterministic processes in clean soil into stochastic processes in Cr-contaminated soils. Virus-host linkage results showed that the niche breadth of bacteria and viruses was closely related. The normalized stochasticity ratio of viral functional assembly was positively correlated with the Simpson index of the bacteria (p < 0.05). The results suggested that the stochasticity of viral functional assembly was conducive to facilitating the functional redundancy of bacterial communities and their evolution toward the deterministic direction. [Display omitted] • Bacteria maintained functional redundancy under Cr exposure. • Deterministic process dominated the assemblies of bacterial and viral taxa. • Bacterial and viral genes were driven by distinct processes due to Cr exposure. • Viral communities facilitated the functional redundancy of host bacteria. [ABSTRACT FROM AUTHOR]

In Arabidopsis , three lipase-like regulators, SAG101, EDS1, and PAD4, act downstream of resistance protein-associated defense signaling. Although the roles of SAG101, EDS1, and PAD4 in biotic stress have been extensively studied, little is known about their functions in plant responses to abiotic stresses. Here, we show that SAG101, EDS1, and PAD4 are involved in the regulation of freezing tolerance in Arabidopsis . With or without cold acclimation, the sag101 , eds1 , and pad4 single mutants, as well as their double mutants, exhibited similarly enhanced tolerance to freezing temperatures. Upon cold exposure, the sag101 , eds1 , and pad4 mutants showed increased transcript levels of C-REPEAT/DRE BINDING FACTORs and their regulons compared with the wild type. Moreover, freezing-induced cell death and accumulation of hydrogen peroxide were ameliorated in sag101 , eds1 , and pad4 mutants. The sag101 , eds1 , and pad4 mutants had much lower salicylic acid (SA) and diacylglycerol (DAG) contents than the wild type, and exogenous application of SA and DAG compromised the freezing tolerance of the mutants. Furthermore, SA suppressed the cold-induced expression of DGATs and DGKs in the wild-type leaves. These findings indicate that SAG101, EDS1, and PAD4 are involved in the freezing response in Arabidopsis , at least in part, by modulating the homeostasis of SA and DAG. [ABSTRACT FROM AUTHOR]

Cysteine (Cys)-rich proteins (CRPs) are frequently associated with plant defense and stress resistance. Viola baoshanensis is a cadmium (Cd) hyper-accumulating plant whose CRPs-based defense systems are so far poorly understood. Next generation sequencing (NGS) techniques and a specialist searching tool, CrpExcel, were employed for identifying CRPs in V. baoshanensis . The transcriptome sequences of V. baoshanensis were assembled primarily from 454FLX/Hiseq2000 reads of plant cDNA sequencing libraries. CrpExcel was then used to search the ORFs and 9687 CRPs were identified, and included zinc finger (ZF) proteins, lipid transfer proteins, thaumatins and cyclotide precursors. Real-time PCR results showed that all CRP genes tested are constitutively expressed, but the genes of defensive peptides showed greater up-regulated expression than those of ZF-proteins in Cd- and/or wounding (Wd) treatments of V. baoshanensis seedlings. The NGS-derived sequences of cyclotide precursor genes were verified by RT-PCR and ABI3730 sequencing studies, and 32 novel cyclotides were identified in V. baoshanensi s. In general, the metal-binding sites of ZF-containing CRPs also represented the potential vulnerable targets of toxic metals. This study provides broad insights into CRPs-based defense systems and stress-vulnerable targets in V. baoshanensis . It now brings the number of cyclotide sequences in V. baoshanensis to 53 and based on projections from this work, the number of cyclotides in the Violaceae is now conservatively estimated to be >30000. [ABSTRACT FROM AUTHOR]

Lipid remodeling is crucial for hypoxic tolerance in animals, whilst little is known about the hypoxia-induced lipid dynamics in plants. Here we performed a mass spectrometry-based analysis to survey the lipid profiles of Arabidopsis rosettes under various hypoxic conditions. We observed that hypoxia caused a significant increase in total amounts of phosphatidylserine, phosphatidic acid and oxidized lipids, but a decrease in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Particularly, significant gains in the polyunsaturated species of PC, PE and phosphatidylinositol, and losses in their saturated and mono-unsaturated species were evident during hypoxia. Moreover, hypoxia led to a remarkable elevation of ceramides and hydroxyceramides. Disruption of ceramide synthases LOH1, LOH2 and LOH3 enhanced plant sensitivity to dark submergence, but displayed more resistance to submergence under light than wild type. Consistently, levels of unsaturated very-long-chain (VLC) ceramide species (22:1, 24:1 and 26:1) predominantly declined in the loh1, loh2 and loh3 mutants under dark submergence. In contrast, significant reduction of VLC ceramides in the loh1-1 loh3-1 knockdown double mutant and lacking of VLC unsaturated ceramides in the ads2 mutants impaired plant tolerance to both dark and light submergences. Evidence that C24:1-ceramide interacted with recombinant CTR1 protein and inhibited its kinase activity in vitro, enhanced ER-to-nucleus translocation of EIN2-GFP and stabilization of EIN3-GFP in vivo, suggests a role of ceramides in modulating CTR1-mediated ethylene signaling. The dark submergence-sensitive phenotypes of loh mutants were rescued by a ctr1-1 mutation. Thus, our findings demonstrate that unsaturation of VLC ceramides is a protective strategy for hypoxic tolerance in Arabidopsis. [ABSTRACT FROM AUTHOR]

In Arabidopsis thaliana, acyl-CoA-binding proteins ( ACBPs) are encoded by a family of six genes ( ACBP1 to ACBP6), and are essential for diverse cellular activities. Recent investigations suggest that the membrane-anchored ACBPs are involved in oxygen sensing by sequestration of group VII ethylene-responsive factors under normoxia. Here, we demonstrate the involvement of Arabidopsis ACBP3 in hypoxic tolerance. ACBP3 transcription was remarkably induced following submergence under both dark ( DS) and light ( LS) conditions. ACBP3-overexpressors ( ACBP3- OEs) showed hypersensitivity to DS, LS and ethanolic stresses, with reduced transcription of hypoxia-responsive genes as well as accumulation of hydrogen peroxide in the rosettes. In contrast, suppression of ACBP3 in ACBP3- KOs enhanced plant tolerance to DS, LS and ethanol treatments. By analyses of double combinations of OE-1 with npr1-5, coi1-2, ein3-1 as well as ctr1-1 mutants, we observed that the attenuated hypoxic tolerance in ACBP3- OEs was dependent on NPR1- and CTR1-mediated signaling pathways. Lipid profiling revealed that both the total amounts and very-long-chain species of phosphatidylserine (C42:2- and C42:3- PS) and glucosylinositolphosphorylceramides (C22:0-, C22:1-, C24:0-, C24:1-, and C26:1- GIPC) were significantly lower in ACBP3- OEs but increased in ACBP3- KOs upon LS exposure. By microscale thermophoresis analysis, the recombinant ACBP3 protein bound VLC acyl-CoA esters with high affinities in vitro. Further, a knockout mutant of MYB30, a master regulator of very-long-chain fatty acid ( VLCFA) biosynthesis, exhibited enhanced sensitivities to LS and ethanolic stresses, phenotypes that were ameliorated by ACBP3- RNAi. Taken together, these findings suggest that Arabidopsis ACBP3 participates in plant response to hypoxia by modulating VLCFA metabolism. [ABSTRACT FROM AUTHOR]

In space, circadian rhythms are prone to alteration. Head-down (–6°) bed rest (HDBR) is an approach simulating the weightlessness condition, which allows effects of weightlessness on physiological variables to be studied on the ground. In this work, we analyzed the changes in diurnal rhythms of activity, sleep-wake cycles, and cardiovascular responses in a 45-day HDBR. All subjects exhibited increased daytime sleep, whereas the total sleep time was comparable. The results of wrist activity monitoring showed a significant reduction during HDBR and recovery after HDBR. Moreover, changes in the average frequency, amplitude, and phase of heart rate were observed. Analysis of heart rate variability showed a decrease in both high-frequency and low-frequency power after HDBR. Together, these data demonstrate that HDBR can alter the diurnal rhythms of a number of physiological processes, some of which might be attributed to reduction in activity of the autonomic nervous system. [ABSTRACT FROM AUTHOR]

Highlights: [•] Ten strains of ACC-utilizing or N2-fixing bacteria were isolated and identified. [•] The isolated PGPB strongly promoted the growth of plants on sterilized tailings. [•] A consortium of 10 strains did not further increase the growth-promoting efficiency. [•] Plant growth-promoting effects of the PGPB were weaker in non-sterilized tailings. [Copyright &y& Elsevier]

Six organic acids (oxalic, malonic, malic, citric, palmitic and linolenic acid) in two arsenic (As) hyperaccumulators (Pteris multifida and Pteris vittata) and a non-hyperaccumulator fern (Pteris semipinnata) exposed to different As concentrations (0, 5, 20 and 40 mg As L-1) under hydroponic conditions were determined using gas chromatography-mass spectrometry (GC-MS). Three fern species were collected from an uncontaminated site, but two As-hyperaccumulators were also collected from an As-contaminated site. Furthermore, the time-course effect of organic acid production in P. multifida and P. semipinnata collected from the uncontaminated site were also studied under 0 and 20 mg As L-1 treatments with a sampling interval at 0, 6, 12, 24 and 36 h. After esterifying (H2SO4-CH3OH), extracting (CH2Cl2), washing (saturated NaCl) and drying (anhydrous Na2SO4), these organic acids were isolated (Column: HP Ultra 2, 50 m × 0.2 mM × 0.33 µM; Carrier gas: He). There was no significant increase in the concentrations of the six organic acids in the fronds and roots of the three fern species sampled from an uncontaminated site under 5 or 40 mg As L-1 treatments. In addition, there were also no significant differences in the concentrations of organic acids among the three fern species under the same As concentration treatments. Concentrations of malic, oxalic and linolenic acids in the fronds and roots of two As hyperaccumulators collected from an As-contaminated or uncontaminated site and the non-hyperaccumulator collected from an uncontaminated site followed the sequence of malic acid > oxalic acid > linolenic acid. As for time-course effect, compared to P. semipinnata, a significant increase was observed in concentrations of oxalic and linolenic acid in P. multifida over time under 20 mg As L-1 treatment. In general, the changes of organic acid concentrations in As hyperaccumulators did not directly contribute to As accumulation. [ABSTRACT FROM AUTHOR]

Abstract: Trophic groups and functional guilds of soil nematodes were measured under four mine tailing subsystems in the Baoshan lead/zinc mine, Hunan Province, southern China to test the indicator value of nematodes for heavy metal pollution. No obvious correlation was found between heavy metal concentration and the total number of nematodes. However, the densities of c–p3, c–p4 and c–p5 nematodes were negatively correlated with Pb and Zn concentrations, suggesting that the abundance of nematode groups of high c–p values is useful indicators of heavy metal contamination. The “weighted faunal analysis” provided a better assessment of soil health condition than Maturity Index (MI) in situations where there were extremely low numbers of soil nematodes. Results showed that the effect of heavy metal contamination on soil nematodes might be strongly influenced by plants. Although the abundance of plant-feeding nematodes did not reflect the heavy metal conditions in the soil, it might be used as an index for assessing the soil remediation potential of pioneering plants. Patrinia villosa seems superior to Viola baoshanensis as a pioneer plant species for soil remediation based on analysis of rhizosphere nematode community. [Copyright &y& Elsevier]

Many Viola plants growing in mining areas exhibit high levels of cadmium (Cd) tolerance and accumulation, and thus are ideal organisms for comparative studies on molecular mechanisms of Cd hyperaccumulation. However, transcriptomic studies of hyperaccumulative plants in Violaceae are rare. Viola baoshanensis is an amazing Cd hyperaccumulator in metalliferous areas of China, whereas its relative V. inconspicua is a non-tolerant accumulator that resides at non-metalliferous sites. Here, comparative studies by transcriptome sequencing were performed to investigate the key pathways that are potentially responsible for the differential levels of Cd tolerance between these two Viola species. A cascade of genes involved in the ubiquitin proteosome system (UPS) pathway were observed to have constitutively higher transcription levels and more activation in response to Cd exposure in V. baoshanensis, implying that the enhanced degradation of misfolded proteins may lead to high resistance against Cd in this hyperaccumulator. Many genes related to sucrose metabolism, especially those involved in callose and trehalose biosynthesis, are among the most differentially expressed genes between the two Viola species, suggesting a crucial role of sucrose metabolism not only in cell wall modification through carbon supply but also in the antioxidant system as signaling molecules or antioxidants. A comparison among transcriptional patterns of some known transporters revealed that several tonoplast transporters are up-regulated in V. baoshanensis under Cd stress, suggesting more efficient compartmentalization of Cd in the vacuoles. Taken together, our findings provide valuable insight into Cd hypertolerance in V. baoshanensis, and the corresponding molecular mechanisms will be useful for future genetic engineering in phytoremediation. [ABSTRACT FROM AUTHOR]