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IntroductionArbuscular mycorrhizal fungi (AMF) are pivotal in plant resource acquisition, mediating plant interactions, and influencing soil carbon dynamics. However, their biogeographical distribution in Tibetan alpine grasslands remains understudied. MethodsIn this research, we examined the distribution pattern of AMF communities and their key determinants along a 2000-km transect across the Tibetan plateau, encompassing 7 alpine meadows and 8 alpine steppes. ResultsOur findings indicate that AMF community diversity and composition exhibit similarities between alpine meadows and alpine steppes, primarily influenced by latitude and evapotranspiration. At the genus level, Glomus predominated in both alpine meadow (36.49%±2.67%) and alpine steppe (41.87%±2.36%) soils, followed by Paraglomus (27.14%±3.69%, 32.34%±3.28%). Furthermore, a significant decay relationship of AMF community was observed over geographical distance. Null model analyses revealed that random processes predominantly (>50%) drove the assembly of AMF communities. DiscussionIn summary, our study elucidates the spatial distribution pattern of AMF in Tibetan plateau grasslands and underscores the significant influence of geographical and climatic factors on AMF community dynamics.

Abstract Phyllosphere endophytes play a critical role in a myriad of biological functions, such as maintaining plant health and overall fitness. They play a determinative role in crop yield and quality by regulating vital processes, such as leaf functionality and longevity, seed mass, apical growth, flowering, and fruit development. This study conducted a comprehensive bibliometric analysis aiming to review the prevailing research trajectories in phyllosphere endophytes and harness both primary areas of interest and emerging challenges. A total of 156 research articles on phyllosphere endophytes, published between 2002 and 2022, were retrieved from the Web of Science Core Collection (WoSCC). A systematic analysis was conducted using CiteSpace to visualize the evolution of publication frequency, the collaboration network, the co-citation network, and keywords co-occurrence. The findings indicated that initially, there were few publications on the topic of phyllosphere endophytes. However, from 2011 onwards, there was a notable increase in the number of publications on phyllosphere endophytes, gaining worldwide attention. Among authors, Arnold, A Elizabeth is widely recognized as a leading author in this research area. In terms of countries, the USA and China hold the highest rankings. As for institutional ranking, the University of Arizona is the most prevalent and leading institute in this particular subject. Collaborative efforts among the authors and institutions tend to be confined to small groups, and a large-scale collaborative network needs to be established. This study identified the influential journals, literature, and hot research topics. These findings also highlight the interconnected nature of key themes, e.g., phyllosphere endophyte research revolves around the four pillars: diversity, fungal endophytes, growth, and endophytic fungi. This study provides an in-depth perspective on phyllosphere endophytes studies, revealing the identification of biodiversity and microbial interaction of phyllosphere endophytes as the principal research frontiers. These analytical findings not only elucidate the recent trajectory of phyllosphere endophyte research but also provide invaluable insights for similar studies and their potential applications on a global scale.

Abstract Background Soil microbes exist throughout the soil profile and those inhabiting topsoil (0–20 cm) are believed to play a key role in nutrients cycling. However, the majority of the soil microbiology studies have exclusively focused on the distribution of soil microbial communities in the topsoil, and it remains poorly understood through the subsurface soil profile (i.e., 20–40 and 40–60 cm). Here, we examined how the bacterial community composition and functional diversity changes under intensive fertilization across vertical soil profiles [(0–20 cm (RS1), 20–40 cm (RS2), and 40–60 cm (RS3)] in the red soil of pomelo orchard, Pinghe County, Fujian, China. Results Bacterial community composition was determined by 16S rRNA gene sequencing and interlinked with edaphic factors, including soil pH, available phosphorous (AP), available nitrogen (AN), and available potassium (AK) to investigate the key edaphic factors that shape the soil bacterial community along with different soil profiles. The most dominant bacterial taxa were Proteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Crenarchaeota, and Bacteriodetes. Bacterial richness and diversity was highest in RS1 and declined with increasing soil depth. The distinct distribution patterns of the bacterial community were found across the different soil profiles. Besides, soil pH exhibited a strong influence (pH ˃AP ˃AN) on the bacterial communities under all soil depths. The relative abundance of Proteobacteria, Actinobacteria, Crenarchaeota, and Firmicutes was negatively correlated with soil pH, while Acidobacteria, Chloroflexi, Bacteriodetes, Planctomycetes, and Gemmatimonadetes were positively correlated with soil pH. Co-occurrence network analysis revealed that network topological features were weakened with increasing soil depth, indicating a more stable bacterial community in the RS1. Bacterial functions were estimated using FAPROTAX and the relative abundance of functional bacterial community related to metabolic processes, including C-cycle, N-cycle, and energy production was significantly higher in RS1 compared to RS2 and RS3, and soil pH had a significant effect on these functional microbes. Conclusions This study provided the valuable findings regarding the structure and functions of bacterial communities in red soil of pomelo orchards, and highlighted the importance of soil depth and pH in shaping the soil bacterial population, their spatial distribution and ecological functioning. These results suggest the alleviation of soil acidification by adopting integrated management practices to preserve the soil microbial communities for better ecological functioning.

The “Green Belt and Road Initiative” (GBRI) is China’s international cooperation strategy aimed at expanding international collaborations between China, Asia, and Europe through regional trade, policy dialogue, and cultural exchange in order to promote the achievement of sustainable development goals (SDGs). Identifying the development characteristics and deficiencies of Belt and Road countries is critical to investment and policymaking decisions. Here, we incorporated progress evenness across SDGs based on biodiversity measurements to establish a comprehensive assessment system and evaluated the sustainable development status and trajectory of Belt and Road countries from 2017 to 2021. Our results suggest that, although most countries have experienced progress toward SDGs, disregarding evenness among goals tended to result in the overestimation of the current achievements and ignore regional gaps. Economically developed member countries in the Organization for Economic Co-operation and Development (OECD) were more successful in achieving SDGs, but they also faced development bottlenecks owing to uneven development among the 17 goals, with particular shortcomings in goals related to climate actions. However, many countries with relatively poor economies, mostly in Central and Southeast Asia, performed well on eco-environment-related SDGs. Therefore, complementary collaboration among countries may provide a green development pathway to rapidly promote the achievement of SDGs in the Belt and Road region, which emphasizes the urgency and potential for the GBRI. In essence, while uneven development is a tremendous challenge for Belt and Road countries, it presents an opportunity to enhance regional cooperation in support of the GBRI.

In the Tibetan grasslands, the distribution patterns of the microbial community structure and function along elevation gradients have attracted considerable attention due to the wide distribution of mountain slopes, but the controlling factors of these patterns are still unclear. Here we investigated the taxonomy and potential functions of soil bacteria along an elevation gradient in a Tibetan mountainous grassland in 2 years, aiming to explore the elevation patterns of the bacterial structure and function and the underlying drivers. High-throughput sequencing and environment attribute measurements were conducted to survey the bacterial and environment characters. Furthermore, PICRUSt2 for prediction of bacterial functions, iCAMP for unraveling the drivers controlling community assembly, and HMSC for variance partitioning of bacterial community composition were used. Elevation did not significantly affect the bacterial diversity but changed their composition, driven by both deterministic and stochastic processes. In addition, elevation did not significantly affect the relative importance of deterministic and stochastic processes. Soil carbon, nitrogen, and temperature were important deterministic factors in driving bacterial community structure. The genus Solirubrobacter in Actinobacteriota was identified as most elevation discriminatory. Based on these observations, the bacterial community in the Tibetan mountainous grasslands was more controlled by edaphic factors than temperature, indicating their relative stability under climate change scenarios.

The riparian zone is an important ecological corridor connecting the upstream and downstream rivers. Its highly complex biological and physical environments significantly affect the biogeographical pattern of species and various ecosystem functions. However, in alpine riparian ecosystems, the distribution patterns and drivers of arbuscular mycorrhizal (AM) fungi, a group of functionally important root-associated microorganisms, remain poorly understood. In this study, we investigated the AM fungal diversity and community composition in near-bank (wetland) and far-bank (alpine meadows) soils along the Niaqu River in the Nam Co watershed, and assessed the relative importance of abiotic and biotic filtering in shaping these distributions. Overall, 184 OTUs were identified in the riparian ecosystem, predominantly belonging to the genus Glomus, especially in the downstream soils, and Claroideoglomus in near-bank soils. AM fungal colonization, spore density, and α diversity showed an overall increasing trend along the river, while the extraradical hyphae declined dramatically from the middle of the river. AM fungal communities significantly varied between the wetland and alpine meadows in the riparian zone, mainly driven by the geographic distance, soil water content, soil pH, and plant communities. Specifically, soil pH was the principal predictor of AM fungal community in near-bank wetland soils, while soil water content had a most substantial direct effect in alpine meadows. These findings indicate that abiotic factors are the most important divers in shaping AM fungal communities at the watershed scale, which could be helpful in alpine riparian biodiversity conservation and management.

Arbuscular mycorrhizal (AM) fungi play a critical role in promoting plant growth and sustainability of a healthy ecosystem. Chinese fir (Cunninghamia lanceolata), most extensively grown in southern China, form a symbiotic association with AM fungi. However, most studies have exclusively focused on AM fungi associated with different aged Chinese fir plantations. It remains poorly understood how different forest patterns of Chinese fir regulate the AM fungal community. Therefore, Chinese fir with three different patterns (i.e., monoculture plantation, mixed plantation, and natural forest) were studied to evaluate the AM fungal communities under different planting patterns through Illumina Miseq high-throughput sequencing. Overall, 96 AM fungal operational taxonomic units (OTUs) were identified, belonging to genus Glomus, Archaeospora, Acaulospora, Diversispora, Gigaspora, and Scutellospora. However, monoculture showed the maximum number of AM fungal species (82) compared to mixed (55) and natural forests (73). Non-metric multi-dimensional scaling (NMDS) analysis revealed significant AM fungal community differences among different forest patterns. Canonical correlation analysis and mantel test revealed that edaphic factors, including soil pH, TN, TP, TK, AN, AK, SOM, Mg and Mn had a significant effect in shaping the AM fungal communities. These findings could provide a microbial basis for local forest management and diversity protection.

Rhizosphere soil microbial communities substantially impact plant growth by regulating the nutrient cycle. However, dynamic changes in soil microbiota under different tree ages have received little attention. In this study, changes in soil physicochemical properties, as well as bacterial diversity and community structures (by high-throughput Illumina MiSeq sequencing), were explored in pomelo trees of different ages (i.e., 10, 20, and 30 years) under red and paddy soils cultivated by farmers with high fertilizer input. Moreover, soil factors that shape the bacterial community, such as soil pH, AP (available phosphorous), AK (available potassium), and AN (available nitrogen), were also investigated. Results showed that pH significantly decreased, while AP, AK, and AN increased with increasing tree age under red soil. For paddy soil, pH was not changed, while AP was significantly lower under 10-year-old pomelo trees, and AK and AN contents were minimum under 30-year-old pomelo trees. Both soil types were dominated by Proteobacteria, Acidobacteria, and Actinobacteria and showed contrasting patterns of relative abundance under different tree age groups. Bacterial richness and diversity decreased with increasing tree age in both soil types. Overall, bacterial community composition was different under different tree ages. RDA analysis showed that soil pH, AP, and AN in red soil, and pH and AP in paddy soil showed the most significant effects in changing the bacterial community structure. A random forest model showed Sinomonas and Streptacidiphilus in red soil, while Actinoallomurus and Microbacterium in paddy soil were the most important genera explaining the differences among different age groups. The ternary plot further revealed that genera enrichment for Age_30 was higher than that for Age_10 and Age_20 in red soil, whereas specific genera enrichment decreased with increasing tree age under paddy soil. Co-occurrence network revealed that bacterial species formed a complex network structure with increasing tree age, indicating a more stable microbial association under 20 and 30 years than 10-year-old pomelo trees. Hence, contrasting patterns of changes in soil physicochemical properties and soil microbial communities were recorded under different tree ages, and tree ages significantly affected the bacterial community structure and richness. These findings provide valuable information regarding the importance of microbes for the sustainable management of pomelo orchards by optimizing fertilizer input for different ages of trees.

Effects of arbuscular mycorrhizal fungi (AMF) on plants span the continuum from mutualism to parasitism due to the plant–AMF specificity, which obscures the utilization of AMF in the restoration of degraded lands. Caragana korshinskii, Hedysarum laeve, Caragana microphylla, and Poa annua are the most frequently used plants for revegetation in Kubuqi Desert, China, and the influence of AMF on their re-establishment remains to be explored further. Herein, using a greenhouse experiment, we tested the plant–AMF feedbacks between the four plant species and their conspecific or heterospecific AMF, retrieved from their rhizosphere in the Kubuqi Desert. AMF showed beneficial effects on plant growth for all these plant-AMF pairs. Generally, AMF increased the biomass of C. korshinskii, H. laeve, C. microphylla, and P. annua by 97.6, 50.6, 46.5, and 381.1%, respectively, relative to control. In addition, the AMF-plant specificity was detected. P. annua grew best, but C. microphylla grew worst with conspecific AMF communities. AMF community from P. annua showed the largest beneficial effect on all the plants (with biomass increased by 63.9–734.4%), while the AMF community from C. microphylla showed the least beneficial effect on all the plants (with biomass increased by 9.9–59.1%), except for P. annua (a 292.4% increase in biomass). The magnitude of AMF effects on plant growth was negatively correlated with the complexity of the corresponding AMF co-occurrence networks. Overall, this study suggests that AMF effects on plant growth vary due to plant-AMF specificity. We also observed the broad-spectrum benefits of the native AMF from P. annua, which indicates its potential utilization in the restoration of the desert vegetation.

Plants and arbuscular mycorrhizal fungi (AMF) can form complex symbiotic networks based on functional trait selection, contributing to the maintenance of ecosystem biodiversity and stability. However, the selectivity of host plants on AMF and the characteristics of plant-AMF networks remain unclear in Tibetan alpine meadows. In this study, we studied the AMF communities in 69 root samples from 23 plant species in a Tibetan alpine meadow using Illumina-MiSeq sequencing of the 18S rRNA gene. The results showed a significant positive correlation between the phylogenetic distances of plant species and the taxonomic dissimilarity of their AMF community. The plant-AMF network was characterized by high connectance, high nestedness, anti-modularity, and anti-specialization, and the phylogenetic signal from plants was stronger than that from AMF. The high connected and nested plant-AMF network potentially promoted the interdependence and stability of the plant-AMF symbioses in Tibetan alpine meadows. This study emphasizes that plant phylogeny and plant-AMF networks play an important role in the coevolution of host plants and their mycorrhizal partners and enhance our understanding of the interactions between aboveground and belowground communities.

Grazing exclusion is an effective management practice to restore grassland ecosystem functioning. However, little is known about the role of soil microbial communities in regulating grassland ecosystem functioning during long-term ecosystem restorations. We evaluated the recovery of a degraded semiarid grassland ecosystem in northern China by investigating plant and soil characteristics and the role of soil microbial communities in ecosystem functioning after 22 years of grazing exclusion. Grazing exclusion significantly increased the alpha diversity and changed the community structure of bacteria, but did not significantly affect the alpha diversity or community structure of fungi. The higher abundance of copiotrophic Proteobacteria and Bacteroidetes with grazing exclusion was due to the higher carbon and nutrient concentrations in the soil, whereas the high abundance of Acidobacteria in overgrazed soils was likely an adaptation to the poor environmental conditions. Bacteria of the Sphingomonadaceae family were associated with C cycling under grazing exclusion. Bacteria of the Nitrospiraceae family, and especially of the Nitrospira genus, played an important role in changes to the N cycle under long-term exclusion of grazing. Quantitative PCR further revealed that grazing exclusion significantly increased the abundance of nitrogen fixing bacteria (nifH), ammonia oxidizers (AOA and AOB), and denitrifying bacteria (nirK and nosZ1). Denitrifying enzyme activity (DEA) was positively correlated with abundance of denitrifying bacteria. The increase in DEA under grazing exclusion suggests that the dependence of DEA on the availability of NO3– produced is due to the combined activity of ammonia oxidizers and denitrifiers. Our findings indicate that decades-long grazing exclusion can trigger changes in the soil bacterial diversity and composition, thus modulating the restoration of grassland ecosystem functions, carbon sequestration and soil fertility.

Increasing atmospheric nitrogen (N) deposition causes profound changes in the plant community, significantly threatening the terrestrial ecosystem function and stability worldwide. Random migration is a primary determinant of plant community assembly in the neutral model. However, whether its role is affected by N deposition is obscure. Therefore, the effects of eight N application rates (0, 1, 2, 3, 5, 10, 15, and 20 g N m−2 yr−1) on the estimated migration rate of plant community were examined in a long-term field study in a semiarid steppe. Our results indicated that N addition significantly impacted the estimated migration rate (F = 4.89, P

Random migration often plays important roles in soil microbial community assembly. However, it remains unexplored that whether its role is affected by anthropogenic disturbances, and whether the effects of different disturbances are consistent. Here, we report a novel and general pattern that different disturbances consistently restrain the role of migration in soil bacterial community assembly. We mimicked 16 types of anthropogenic disturbances relevant to a Eurasian steppe ecosystem, including removing different number of plant functional groups, mowing, adding nitrogen, adding phosphorus, watering, warming, and some of their combinations. The estimated migration rates in soil bacterial community assembly with Stephen Hubbell’s neutral model decreased by 0.19–6.29% under these disturbances. The relative change in migration rate was correlated with the deterministic change in community composition and the relative change in soil pH. Our results suggested that the intensifying anthropogenic disturbances may restrain the random dispersal, colonization and distribution of soil microorganisms.

Majority of plants are linked below-ground through common mycorrhizal networks (CMNs). The formation of CMNs between the roots of conspecific and heterospecific plant individuals influences the distribution of limiting nutrients, e.g., nitrogen (N) among the interconnected plants. In various ecosystems, the availability of N is being increased substantially; however, the effect of elevated N on the existence and functionality of CMNs in semi-arid regions of Inner Mongolia remains largely unexplored. Therefore, to verify the development of CMNs and their functionality under increasing N concentration, we incorporated different levels of N fertilizer, i.e., N0 = 0, N1 = 7.06, N2 = 14.12, and N3 = 21.18 mg kg−1, and established Leymus chinensis (L. chinensis) as a donor and the recipient plant in a specially designed portioned root-box. For the establishment of CMNs among the plants, compartments were separated via 37 μm mesh. The 15N isotope tracer technique and microscopic analysis evidenced the presence of CMNs because the extraradical hyphae originated from the donor side and crossed 37 μm mesh of the recipient plant compartment. The 15N recovery was highest at N1 in the donor (18.38%) and recipient (7.89%) plants, while the average transfer rate of 15N to recipient plant was 21–65% with a maximum transfer rate at N2 treatment. The establishment of CMNs significantly improved the donor and recipient plants chlorophyll contents and plant biomass at low N levels. Moreover, the AM fungal extraradical hyphae also released a special kind of protein called glomalin-related soil proteins (GRSPs) that improved the soil structure in terms of mean weight diameter (MWD), thereby improving the soil organic carbon (SOC). Interestingly, the mycorrhizal network had a more profound impact on its neighboring plants than the host plant. In short, the present investigation emphasizes the presence of CMNs in the typical steppe of Inner Mongolia with vital roles in nutrient transfer and improvement of plant growth and soil properties.

Nutrient resorption from senesced leaves is an important mechanism for nutrient conservation in plants. However, little is known about the effect of grazing on plant nutrient resorption from senesced leaves, especially in semiarid ecosystems. Here, we evaluated the effects of grazing on N and P resorption in the three most dominant grass species in a typical steppe in northern China. We identified the key pathways of grazing-induced effects on N and P resorption efficiency. Grazing increased N and P concentrations in the green leaves of Leymus chinensis and Stipa grandis but not in Cleistogenes squarossa. Both L. chinensis and S. grandis exhibited an increasing trend of leaf N resorption, whereas C. squarrosa recorded a decline in both leaf N and P resorption efficiency under grazing. Structural equation models showed that grazing is the primary driver of the changes in N resorption efficiency of the three dominant grass species. For L. chinensis, the P concentration in green and senesced leaves increased the P resorption efficiency, whereas the senesced leaf P concentration played an important role in the P resorption efficiency of C. squarrosa. Grazing directly drove the change in P resorption efficiency of S. grandis. Our results suggest that large variations in nutrient resorption patterns among plant species depend on leaf nutritional status and nutrient-use strategies under overgrazing, and indicate that overgrazing may have indirect effects on plant-mediated nutrient cycling via inducing shifts in the dominance of the three plant species.

Arbuscular mycorrhizal fungi (AMF), which form symbioses with most land plants, could benefit their hosts and potentially play important roles in revegetation of degraded lands. However, their application in revegetation of desert grasslands still faces challenges and uncertainties due to the unclear specificity of AMF-plant interactions. Here, Caragana korshinskii and Caragana microphylla were inoculated with either conspecific (home) or heterospecific (away) AM fungal communities from the rhizosphere of three common plant species (C. korshinskii, C. microphylla and Hedysarum laeve) in Kubuqi Desert, China. AMF communities of the inocula and their home and away effects on growth and nutrition status of two Caragana species were examined. Results showed that AMF communities of the three inocula from C. korshinskii, H. laeve and C. microphylla were significantly different, and were characterized by high abundance of Diversispora, Archaeospora, and Glomus, respectively. The shoot biomass, photosynthetic rate, foliar N and P contents of C. korshinskii only significantly increased under home AMF inoculation by 167.10%, 73.55%, 9.24%, and 23.87%, respectively. However, no significant effects of AMF on C. microphylla growth were found, regardless of home or away AMF. Positive correlations between C. korshinskii biomass and the abundance of AMF genus Diversispora were found. Our study showed strong home advantage of using native AMF community to enhance C. korshinskii growth in the desert and presented a potentially efficient way to use native AMF in restoration practices.

Luminescent Cu(I) complexes are promising emitting materials for electroluminescent devices due to their low cost and abundant resources, as well as high emission efficiency. It is well-known that N-heterocyclic carbenes (NHCs) are excellent ligands for transition metal complexes. To investigate the photophysical properties of Cu(I)-NHC complexes, a series of new mononuclear four-coordinate Cu(I) complexes supported by the diphosphine ligand bis[2-(diphenylphosphino)phenyl]ether (POP) and the NHC ligands, consisting of imidazolylidene and pyrimidine units, were synthesized and fully characterized. To tune the photophysical properties of these Cu(I)-NHC complexes, the NHC ligands were attached with electron-withdrawing/donating groups (fluorine, chlorine, methyl and methoxyl) at the pyrimidine unit. All of these Cu(I)-NHC complexes adopt the typical distorted tetrahedral configuration. The electron-donating groups can lead to shorter Cu–N bond distances and longer Cu–C bond distances compared to the electron-withdrawing groups. Theoretical calculation results show that the highest occupied molecular orbitals are mainly distributed on the Cu(I) ion, POP, and carbene unit, while the lowest unoccupied molecular orbitals are mostly located on the pyrimidine unit of NHC ligands. The lowest energy electronic transitions of these Cu(I)-NHC complexes are mainly the metal-to-ligand charge transfer transition and ligand-to-ligand charge transfer transition. These Cu(I)-NHC complexes in solid state show tunable emissions from 530 to 618 nm with efficiencies of 0.5–38.1% at room temperature. The photophysical behaviors of these complexes at 298 and 50 K match well with the thermally activated delayed fluorescence (TADF) characteristics.

Common mycorrhizal networks (CMNs) allow the transfer of nutrients between plants, influencing the growth of the neighboring plants and soil properties. Cleistogene squarrosa (C. squarrosa) is one of the most common grass species in the steppe ecosystem of Inner Mongolia, where nitrogen (N) is often a key limiting nutrient for plant growth, but little is known about whether CMNs exist between neighboring individuals of C. squarrosa or play any roles in the N acquisition of the C. squarrosa population. In this study, two C. squarrosa individuals, one as a donor plant and the other as a recipient plant, were planted in separate compartments in a partitioned root-box. Adjacent compartments were separated by 37 µm nylon mesh, in which mycorrhizal hyphae can go through but not roots. The donor plant was inoculated with arbuscular mycorrhizal (AM) fungi, and their hyphae potentially passed through nylon mesh to colonize the roots of the recipient plant, resulting in the establishment of CMNs. The formation of CMNs was verified by microscopic examination and 15N tracer techniques. Moreover, different levels of N fertilization (N0 = 0, N1 = 7.06, N2 = 14.15, N3 = 21.19 mg/kg) were applied to evaluate the CMNs’ functioning under different soil nutrient conditions. Our results showed that when C. squarrosa−C. squarrosa was the association, the extraradical mycelium transferred the 15N in the range of 45−55% at different N levels. Moreover, AM fungal colonization of the recipient plant by the extraradical hyphae from the donor plant significantly increased the plant biomass and the chlorophyll content in the recipient plant. The extraradical hyphae released the highest content of glomalin-related soil protein into the rhizosphere upon N2 treatment, and a significant positive correlation was found between hyphal length and glomalin-related soil proteins (GRSPs). GRSPs and soil organic carbon (SOC) were significantly correlated with mean weight diameter (MWD) and helped in the aggregation of soil particles, resulting in improved soil structure. In short, the formation of CMNs in this root-box experiment supposes the existence of CMNs in the typical steppe plants, and CMNs-mediated N transfer and root colonization increased the plant growth and soil properties of the recipient plant.

1,2,4-Triazole and its derivatives have been investigated extensively in the construction of coordination polymers. Using a 1,2,4-triazole ligand 1,3-di-(1,2,4-triazole-4-yl)benzene (dtb), a new three-dimensional coordination polymer, {[Cd2(dtb)2(SO4)(H2O)]·(1,2-H2bdc)·SO4}n (1) (1,2-H2bdc = 1,2-benzenedicarboxylic acid), was synthesized under solvothermal conditions. Single-crystal X-ray diffraction analysis revealed that there are two crystallographically different Cd(II) ions in 1 with distorted pentagonal bipyramidal [CdN4O3] geometry and distorted octahedral [CdN4O2] geometry, respectively. The Cd1 atoms are connected by dtb ligands to generate Cd4(dtb)8 secondary building units (SUBs), and the SUBs are further linked by Cd2 atoms into a three-dimensional network with two different one-dimensional channels of 14.63(2) × 14.63(2) and 7.54(2) × 7.54(2) Å2 along the c axis. The topological analysis of the framework has also been discussed. In addition, compound 1 exhibits strong fluorescence emission in the solid state at room temperature.

Abstract Explaining the persistence of mutualism remains a challenge in ecology and evolutionary biology. The evolutionary stability of arbuscular mycorrhiza, a most widespread and ancient mutualistic association, is particularly intriguing because plants lack apparent mechanisms to prevent cheaters from gaining competitive advantages over cooperators. We developed a triple isotopic labeling method (14C, 32P, and 33P) within a split‐root design to measure the exchange of carbon (C) and phosphorus (P) between the host plant and two mycorrhizal partners across a soil P gradient. Host plant preferentially allocated more C to the roots associated with the fungus delivering higher P per unit plant C, and the strength of preferential allocation decreased with increasing soil P availability. The host plant received more P per unit of allocated C from the better fungus and this advantageous exchange rate did not depend upon P availability. As a result, the level of preferential allocation was correlated with the differential delivery of P from the two fungi. Our findings suggest that plant preferential allocation to better mutualists can stabilize mutualisms in environments limiting in the traded resource, but as the availability of this resource increases, plant preferential allocation declines. This environmental dependence of preferential allocation generates predictions of declining levels in relative abundance of mutualistic fungi in high‐resource environments.

The asymmetric unit of the title co-crystal adduct, C6H4O2·C6F4I2, comprises a half-molecule each of cyclohexa-2,5-diene-1,4-dione and 1,2,4,5-tetrafluoro-3,6-diiodobenzene. The C6F4I2 molecule is almost planar (r.m.s. deviation = 0.0062 Å). In the crystal, the components are connected through O...I halogen bonds [3.017 (11) Å], leading to the formation of wavelike chains along the a axis. The crystal packing also features C—H...F interactions.

In the title compound (systematic name: 1,3-diiodo-4-methoxy-2-nitrobenzene), C7H5I2NO3, the dihedral angle between the benzene ring and the nitro group is 88.0 (3)°, and the methyl group lies almost in the same plane as the ring [deviation = 0.034 (6) Å]. In the crystal, aromatic π–π stacking occurs between inversion-related rings [centroid–centroid separation = 3.865 (3) Å and slippage = 0.642 Å]. A possible weak C—I...π interaction occurs [I...π = 3.701 (2) Å and C—I...π = 130.18 (13)°], but there are no significant intermolecular I...I contacts.

In the title compound, C16H12Br2O6·C2H5OH, the two benzene rings are twisted by 80.64 (5)° and the carboxyl groups form dihedral angles of 72.48 (3) and 89.41 (2)° with the corresponding benzene rings. In the crystal structure, the biphenyl molecules are connected by intermolecular O—H...O and O—H...Br hydrogen bonds, resulting in a chain along the b axis.

In the title compound, C16H10N4O4, the two pyridine rings are twisted by 44.41 (2)° and the ester groups form dihedral angles of 48.77 (4) and 45.75 (2)° with the corresponding pyridine rings. The crystal structure is stabilized by intermolecular C—H...O hydrogen bonds and π–π stacking interactions between the pyridine rings [centroid-to-centroid distance 3.797 (2) Å].

In the title compound, C12H14N4·6H2O, the two pyrimidine rings make a dihedral angle of 5.285 (6)°. Intermolecular O—H...O hydrogen bonds link the six water molecules, generating edge-fused four-, five- or six-membered ring motifs and forming two-dimensional sheets. The sheets are stabilized by the formation of O—H...N hydrogen bonds between the water molecules and the bipyrimidine molecules, resulting in a three-dimensional network.

The title compound, C12H13ClO2, was prepared by the direct asymmetric intermolecular aldol reaction of cyclopentanone and 4-chlorobenzaldehyde catalysed by l-tryptophan in water. The absolute molecular structure was determined to be a racemic twin with 91% (2R,3R) isomer and 9% of the (2S,3S) form. In the crystal structure, the molecules are connected into a one-dimensional chain along the a axis through the formation of intermolecular O—H...O hydrogen bonds. Further, non-conventional C—H...O and C—H...π contacts are observed in the structure, which consolidate the crystal packing.

The title compound, C23H17F2NO, which crystallizes with two independent molecules in the asymmetric unit, was prepared by the cyclization of 4-[2-bis(4-fluorophenyl)methyleneamino]but-3-yn-1-ol at room temperature. The molecules display a tripod conformation. The two fluorophenyl rings make dihedral angles of 79.26 (2) and 85.87 (1)° [86.53 (1) and 83.67 (2)° in the second molecule] with the indole ring, and the dihedral angles between the fluorophenyl rings are 67.74 (2) and 66.33 (2)°, respectively. Furthermore, the indole rings are located on the edge of the respective oxazine half-chair ring systems. Nonconventional C—H...π contacts between indole and fluorophenyl rings are observed.

Two fluorescent Zn(II) polymers (1 and 2) with different dicarboxylic acid co-ligands have been obtained under hydrothermal reaction conditions. In 1 and 2, the flexible bmb adopts two trans-conformations with different Ndonor···N–Csp3···Csp3 torsion angles, generating 3-D interspersed (412·63)-pcu grids. The dicarboxylic acid co-ligands influence the conformation of bmb, which lead to diverse spatial structures from a single helix to a 2-D lattice network. Photoluminescence investigations reveal that 1 has a redshift compared with o-H2oba (4,4'-oxydibenzoic acid) and 2 has a blueshift of 20 nm compared with H2bpdc ([1,1'-biphenyl]-4,4'-dicarboxylic acid), which can be attributed to a ligand-centered charge transfer. [ABSTRACT FROM AUTHOR]

Rhizosphere soil microbial communities substantially impact plant growth by regulating the nutrient cycle. However, dynamic changes in soil microbiota under different tree ages have received little attention. In this study, changes in soil physicochemical properties, as well as bacterial diversity and community structures (by high-throughput Illumina MiSeq sequencing), were explored in pomelo trees of different ages (i.e., 10, 20, and 30 years) under red and paddy soils cultivated by farmers with high fertilizer input. Moreover, soil factors that shape the bacterial community, such as soil pH, AP (available phosphorous), AK (available potassium), and AN (available nitrogen), were also investigated. Results showed that pH significantly decreased, while AP, AK, and AN increased with increasing tree age under red soil. For paddy soil, pH was not changed, while AP was significantly lower under 10-year-old pomelo trees, and AK and AN contents were minimum under 30-year-old pomelo trees. Both soil types were dominated by Proteobacteria, Acidobacteria, and Actinobacteria and showed contrasting patterns of relative abundance under different tree age groups. Bacterial richness and diversity decreased with increasing tree age in both soil types. Overall, bacterial community composition was different under different tree ages. RDA analysis showed that soil pH, AP, and AN in red soil, and pH and AP in paddy soil showed the most significant effects in changing the bacterial community structure. A random forest model showed Sinomonas and Streptacidiphilus in red soil, while Actinoallomurus and Microbacterium in paddy soil were the most important genera explaining the differences among different age groups. The ternary plot further revealed that genera enrichment for Age_30 was higher than that for Age_10 and Age_20 in red soil, whereas specific genera enrichment decreased with increasing tree age under paddy soil. Co-occurrence network revealed that bacterial species formed a complex network structure with increasing tree age, indicating a more stable microbial association under 20 and 30 years than 10-year-old pomelo trees. Hence, contrasting patterns of changes in soil physicochemical properties and soil microbial communities were recorded under different tree ages, and tree ages significantly affected the bacterial community structure and richness. These findings provide valuable information regarding the importance of microbes for the sustainable management of pomelo orchards by optimizing fertilizer input for different ages of trees. [ABSTRACT FROM AUTHOR]