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Changes in soil aggregation with biochar amendment have been investigated extensively, but how biochar affects the chemical composition of organic carbon (C) and biological binding agents in aggregates and their linkage with soil aggregate stability remains unclear. Soil samples were collected in a rice paddy treated with 0 (C0, control), 10 t ha

High waxy crude oil occupies an important proportion in oil resources, and its output is increasing year by year. At the temperature below the wax precipitation point, the wax in crude oil will precipitate and cross-link to form a spatial network structure, resulting in the gelation of crude oil. Once crude oil is gelled, it will exhibit viscoelastic-thixotropic characteristics, which will seriously affect the safety of crude oil pipeline transportation. In this paper, based on the principle of mechanical analogy, the elasticity, viscosity and structural strength of the gelled crude oil are characterized by springs, viscous pots, and structural parameters, respectively. On this basis, the viscoelastic-thixotropic model of waxy crude oil with 9 parameters is established. Meanwhile, the model applicability is verified by experimental data using two waxy crude oils under constant shear stress, shear stress step increase and shear stress hysteresis. Compared with the models in literatures, our model has clear physical meaning, relatively few parameters and high prediction accuracy.

Carbon (C) storage in forest soils can be enhanced through increasing organic C input and decreasing soil heterotrophic respiration (RH). The inhibitory effect of biochar on RH has been extensively studied in agricultural soils, while such an effect and the mechanisms involved remain unknown in forest soils. Here, we examine the response of soil physicochemical and microbial properties to biochar application and how these factors mediate the biochar-induced change in soil RH in a subtropical bamboo plantation. Our results showed that biochar application significantly reduced RH, and markedly altered most of the studied soil properties important for RH in the bamboo plantation. Biochar application did not affect soil temperature and no relationship between soil RH and either soil moisture or labile organic C content was observed, excluding the possibility that biochar reduced the RH through changing soil temperature, moisture or labile organic C content, factors commonly considered to control RH. As compared to the control, biochar application significantly increased the aromatic C content and RubisCO enzyme activity, while decreased β-glucosidase and cellobiohydrolase (CBH) activities. In addition, the soil RH was positively (P

Moso bamboo (Phyllostachys edulis) invasions into adjacent forests have been reported to threaten aboveground biodiversity and alter belowground soil processes. However, the impacts of bamboo invasion on soil microbial community composition, co-occurrence network and enzyme activity remain largely unknown. We presented a cross site field investigation on soil bacterial and fungal communities and enzyme activities in three forests (an original broadleaf forest, a mixed bamboo-broadleaf forest and a pure bamboo forest) at three sites in South China. Our results showed that bamboo invasion consistently increased soil pH (by 6.72% − 17.56%) and soil organic carbon concentrations (by 11.75% − 40.63%) across the three sites. Bamboo invasion consistently decreased fungal ITS gene abundances across the sites, but had little effect on bacterial 16S rRNA gene abundances and diversity indices. The community composition of both bacteria and fungi and their functional guilds differed among the three sites and were significantly (P

Plant viruses trigger numerous responses in their insect vectors. Using iTRAQ-based quantitative proteomics analysis, early responses of the insect vector, the small brown planthopper (Laodelphax striatellus Fallén, SBPH), after acquiring Rice black-streaked dwarf virus (RBSDV) at 3 days and 5 days post first access to diseased plants (padp) were revealed. A total of 582 differentially abundant proteins (DAPs) in SBPH with a fold change1.500 or0.667 (p-value 0.05) were identified. The proteomic analysis in SBPH at 3 days padp revealed 106 highly abundant proteins and 193 of low abundance, while 5 days padp revealed 214 highly abundant proteins and 182 of low abundance. Among them, 51 highly abundant proteins and 42 of low abundance were shown consistently at both 3 days and 5 days padp. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis mapping and Gene Ontology (GO) term classification suggested impairment of mitochondria in SBPH after RBSDV acquisition, and the 77 out of 582 differentially abundant SBPH proteins analyzed by the STRING program revealed the interaction network of the mitochondrial DAPs, showing an overall down-regulation of mitochondrial proteins including the electron transport chain proteins and mitochondrial ribosome proteins. The high abundance of Parkin at 5 days padp suggests that activation of mitophagy induced degradation of mitochondria occurred. Further verification of autophagy/mitophagy-related genes by reverse-transcription quantitative RT-PCR (RT-qPCR) in SBPH after RBSDV acquisition showed up-regulation of the autophagy receptors Optineurin (OPTN), Sequestosome-1 (SQSTM1, also known as p62) and Tax1-binding protein 1 (TAX1BP1) which targets ubiquitinated damaged mitochondria during mitophagy. The phosphorylation of the three autophagy receptors may be up-regulated through an increase of transcription level TRAF-associated NFκB activator (TANK)-binding kinase 1 (TBK1). As a result, an overall reduction in the abundance of mitochondrial proteins was observed and the selective autophagic degradation was up-regulated through increased transcription level of OPTN, p62/SQSTM1, TAX1BP1 and TBK1. Therefore, acquisition of RBSDV associated with up-regulated autophagy and selective mitochondrial degradation in SBPH suggest prevention of mitochondrial-mediated apoptosis and extension of the vector life span. BIOLOGICAL SIGNIFICANCE: RBSDV causes severe yield loss in rice plants. RBSDV is transmitted efficiently only through SBPH. It is important to understand how RBSDV infects SBPH in a persistent, circulative and propagative manner. However, there has been no study on the interaction between RBSDV and SBPH at the early acquisition stage using a proteomics approach. In this study, we combined iTRAQ technique and LC-MS/MS to analyze the vector proteomics at both the initial and latent infection stages after RBSDV acquisition and verified the results by RT-qPCR. Our results revealed that significantly low DAPs were involved in various pathways, including biosynthesis of secondary metabolites, ribosomes, carbon metabolism, biosynthesis of amino acids and TCA cycle. Further clustering of the DAPs revealed significant changes in SBPH mitochondria, including decreased proteins in mitochondrial ribosomes and electron transport chain complex I, II and V. On the other hand, there was a high abundance of Parkin, suggesting the occurrence of mitochondria damage and subsequent Parkin-mediated mitophagy for clearance of impaired mitochondria. Moreover, the decreased level of PMPCB in terms of gene expression and protein abundance suggested decreased PINK1 turnover, promoting Parkin/PINK1-mediated mitophagy. Further analysis on autophagy/mitophagy-related gene transcription level indicated up-regulation of OPTN, p62/SQSTM1, TAX1BP1 and TBK1, promoting selective autophagy in SBPH after RBSDV acquisition. These findings provided new insights into the effects of RBSDV on SBPH after early acquisition by selective degradation of mitochondria, especially on reprogramming of energy metabolism and decreased mitochondria biogenesis, to prevent apoptosis and prolong the life span of SBPH post virus acquisition.

Intensive management practices, such as inorganic fertilization, soil tillage and understory removal, have been widely used to increase bamboo products and economic return in Moso bamboo ( Phyllostachys pubescens ) forests. Arbuscular mycorrhizal fungi (AMF) play a critical role in soil aggregation and carbon cycling. However, little is known about the effects of such long-term soil disturbance on soil AMF community composition and abundance, and their linkage to aggregation in Moso bamboo forests. We investigated soil chemical properties, water-stable soil aggregates, glomalin-related soil protein (GRSP), AMF community composition and biomass across a chronosequence of long-term intensively managed Moso bamboo forests (0, 10, 15, 20 and 25 years of intensive management) in a subtropical region of China. Our results showed that intensive management resulted in significant decreases in soil pH and high accumulations of soil available N, P and K contents. Both soil AMF biomass (indicated by neutral lipid fatty acid) and total GRSP content were significantly decreased with increasing duration under intensive management. High-throughput sequencing showed that intensive management greatly altered soil AMF community composition, and soil available N, P and K were important driving factors shaping it. Soil macroaggregate (>250 μm) proportion decreased by 20–29% in bamboo forest soils after 15 years of intensive management. Soil macroaggregate proportion and organic C content were found significantly and positively correlated with AMF biomass and total GRSP content, respectively, indicating a high risk of soil erosion and organic C depletion when AMF biomass was reduced in long-term intensively managed bamboo forests. In conclusion, our study suggests that long-term intensive management induced alterations in abundance and community composition of AMF are responsible for the decrease in soil aggregation in the Moso bamboo forests. Alternative management practices, such as reduced tillage and organic amendments, are urgently needed to improve AMF community in order to enhance soil aggregation and C sequestration in Moso bamboo forests.

Intensive forest management practices such as organic mulching and heavy fertilization can affect soil microbial composition and function, and soil organic carbon (SOC) forms. However, the linkage between soil microbial community composition and SOC forms is poorly understood in bamboo ( Phyllostachys praecox ) plantations under intensive management (mulching and fertilization). We examined the relationship between SOC (solid state 13 C NMR) and fungal community compositions (real-time PCR, terminal restriction fragment length polymorphism, and clone library) in a chronosequence of intensively managed bamboo plantations (0, 1, 6, 10, and 15 years of stand age). The fungal community composition (internal transcribed spacer, ITS) and function (cellobiohydrolases, cbhI ) and C forms in the top- (0–20) and subsoils (20–40 cm) were determined as fungi dominate cellulose (the main component of plant residues) decomposition in the soil. Soil fungal abundance (copy number of 18S rRNA) was positively correlated to O -alkyl C and aromatic C while negatively correlated to alkyl-C and carbonyl C concentrations. The alkyl C was the most influential SOC fraction on fungal community composition before intensive plantation management was applied, while O -alkyl C was the most influential C-form after more than 5 years of intensive management. The alkyl C, O -alkyl C, aromatic C and carbonyl C together explained 63.2 and 54.2% of the variations in total fungal composition in the top- and subsoils, respectively. Saprotrophic or cellulose-degrading species, mainly Mortierellales sp., Trichoderma sp. and Scheffersomyces sp., dominated the fungal community and the dominance increased with increasing plantation age (combined effects of stand age and duration of intensive management). The increased O -alkyl C concentration caused by increased plantation age explained shifts in the cbhI -containing community composition. Both the cbhI abundance and readily oxidizable C concentration increased with increasing plantation age in the topsoil but not in the subsoil. We conclude that in the intensively managed bamboo plantations changes in organic C forms were closely linked to changes in soil fungal community composition; such linkages have implications for soil nutrient cycling and C transformation in the plantation ecosystem.

Integrating land use type and other geographic information within spatial interpolation has been proposed as a solution to improve the performance and accuracy of soil nutrient mapping at the regional scale. This study developed a non–algorithm approach, i.e., applying inverse distance weighting (IDW) and ordinary kriging (OK), to individual land use types rather than to the whole watershed, to determine if this improved the performance in mapping soil total C (TC), total N (TN), and total P (TP) in a 200–km2 urbanizing watershed in Southeast China. Four land use types were identified by visual interpretation as forest land, agricultural land, green land, and urban land. One hundred and fifty soil samples (0–10 cm) were taken according to land use type and patch size. Results showed that the non–algorithm approach, interpolation based on individual land use types, substantially improved the performance of IDW and OK for mapping TC, TN, and TP in the watershed. Root mean square errors were reduced by 3.9% for TC, 10.7% for TN, and 25.9% for TP by the application of IDW, while the improvements by OK were slightly lower as 0.9% for TC, 7.7% for TN, and 18.1% for TP. Interpolations based on individual land use types visually improved depiction of spatial patterns for TC, TN, and TP in the watershed relative to interpolations by the whole watershed. Substantial improvements might be expected with denser sampling points. We suggest that this non–algorithm approach might provide an alternative to algorithm–based approaches to depict watershed–scale nutrient patterns.

Biochar incorporated into soil has been known to affect soil nutrient availability and act as a habitat for microorganisms, both of which could be related to its particle size. However, little is known about the effect of particle size on soil microbial community structure and function. To investigate short-term soil microbial responses to biochar addition having varying particle sizes and addition rates, we established a laboratory incubation study. Biochar produced via pyrolysis of bamboo was ground into three particle sizes (diameter size Phyllostachys praecox ) plantation soil. The results showed that the fine particle biochar resulted in significantly higher soil pH, electrical conductivity (EC), available potassium (K) concentrations than the medium and coarse particle sizes. The fine-sized biochar also induced significantly higher total microbial phospholipid fatty acids (PLFAs) concentrations by 60.28% and 88.94% than the medium and coarse particles regardless of addition rate, respectively. Redundancy analysis suggested that the microbial community structures were largely dependent of particle size, and that improved soil properties were key factors shaping them. The cumulative CO 2 emissions from biochar-amended soils were 2–56% lower than the control and sharply decreased with increasing addition rates and particle sizes. Activities of α-glucosidase, β-glucosidase, β-xylosidase, N -acetyl-β-glucosaminidase, peroxidase and dehydrogenase decreased by ranging from 7% to 47% in biochar-amended soils over the control, indicating that biochar addition reduced enzyme activities involved carbon cycling capacity. Our results suggest that biochar addition can affect microbial population abundances, community structure and enzyme activities, that these effects are particle size and rate dependent. The fine particle biochar may additionally produce a better habitat for microorganisms compared to the other particle sizes.

Root-associated fungal communities play a key role in plant productivity and soil processes in forest ecosystems. However, how diversity and composition of root-associated fungi change with forest development and their linkage with soil enzyme activities remain largely unknown. We characterized the root-associated fungal communities, plant and soil properties, and extracellular enzyme activities along a chronosequence spanning young (15 years old) to over-mature (63 years old) Pinus massoniana forest development stages. Our results showed that P. massoniana roots harbored diverse root-associated fungal communities and they varied with forest development. Near-mature (36 years old) forest stands had the lowest alpha-diversity but higher relative abundances of ericoid mycorrhizal and activities of enzymes involved in C, N and P acquisition. The relative abundances of ectomycorrhizal fungi and endophyte were higher in middle-age (24 years old) and mature stands (45 years old), whereas the relative abundance of ericoid mycorrhizal fungi was highest in the near-mature stand. Soil pH, soil C:P and N:P ratios were important factors shaping the diversity and composition of root-associated fungal communities. Structural equation modeling indicated that changes in the community composition, but not richness of root-associated fungi, had significant correlations with soil enzymatic C:N and N:P stoichiometry. In conclusion, this study suggests that different stand development stages exhibit distinct diversity and composition of root-associated fungal communities, which affecting soil functions in terms of enzymatic activity.

Biochar has been known as means to increase soil carbon (C) storage, and at the same time to ameliorate soil acidity and enhance plant growth. However, how biochar addition affects microbial community composition and metabolic function in subtropical plantation soils and their linkage with soil quality change is still poorly understood. We selected bamboo stick, corn straw and peel of Carya cathayensis as feedstocks to produce three biochars at 350 °C by slow pyrolysis, and added them to an acid bamboo (Phyllostachys praecox) plantation soil. Changes in soil nutrient and C availability, soil acidity, plant biomass, and microbial function in terms of C source utilization and soil enzyme activities were investigated after a three-month greenhouse trial. The results showed that the biochars from corn straw and peel significantly increased plant biomass, soil pH, organic C, total nitrogen (N) and dissolved organic N contents, while decreased exchangeable H+ and exchangeable Al3+ concentrations. The concentration of total phospholipid fatty acids (PLFAs) was increased significantly under biochars from corn straw and peel. The activities of β-D-cellobiosidase, N-acetylglucosaminidase and acid phosphatase were significantly increased by peel biochar. Soil basal respiration and microbial utilization rate of carbohydrates, carboxylic acids and amino acids compounds were significantly increased under the three biochars, suggesting a higher capacity of biochar-treated soil to catabolize C sources. Increased plant biomass was related to the increased N availability and decreased acidity. Our study suggests that biochar–induced changes in soil acidity and soil nutrient availability are key drivers shaping the composition of microbial communities and enhancing their catabolic capacity, but the effects on soil microbial function vary depending on feedstock origins.

A microcosm study was performed to investigate changes in soil enzyme activities and microbial C- and N-use efficiencies (CUE and NUE) with amendment of biochars prepared at three pyrolysis temperatures (350, 500 and 700 °C) in an acid bamboo (Phyllostachys praecox) forest soil. The results showed that, compared to the non-amended control, biochars produced at 500 and 700 °C significantly (P

Rice black-streaked dwarf virus (RBSDV) can infect a number of gramineous plants and cause severe crop yield losses in southeast Asian countries. The virus is transmitted by small brown planthopper (SBPH) in a persistent circulative manner. The interactions between RBSDV and its different hosts remain unknown. Besides, how the virus adjusts itself to infect different hosts is unclear. In the present study, the relative RNA levels of the thirteen RBSDV genes in rice, maize, wheat, and SBPH were measured by real-time quantitative PCR. P7-1 and P10 genes were predominantly expressed whereas P8 and P7-2 genes were expressed at low levels in plant hosts. Similar to the expression in rice, P7-1 was the most abundantly expressed gene and P8 was expressed at the lowest level in SBPH, indicating that RBSDV adopts the same strategy to infect distinct hosts. The high expression levels of the P7-1 gene in both plants and insect suggest that it can be used as the target gene for disease diagnostics. However, the expression levels of some genes varied from host to host. P5-1, P6 and P9-1, the components of the RBSDV viroplasm, are differentially expressed in different hosts. Moreover, western blot analysis showed that the quantity of the P9-1 protein was more abundant in SBPH than in plant hosts. These data indicate that the virus may adjust its own gene expression to replicate in different hosts. Analysis of time course of gene expression revealed that P7-1 stands out as the only gene highly expressed at the earliest time point and its expression precedes all others throughout infection from 8 to 24 days post-inoculation. The high expression levels of the P7-1 gene suggest that it plays a significant role in RBSDV–host interactions.

Arbuscular mycorrhizal fungi (AMF) play key roles in plant growth, ecosystem sustainability and stability. However, it is still unclear how the soil, root AMF growth and community composition are affected by fertilizer application in subtropical wheat-rice rotation agro-ecosystems. We investigated the impact of different organic and/or inorganic fertilizers on AMF growth and community composition in a long-term experiment field in Zhejiang Province, east China. AMF biomass was determined using 16:1ω5 phospholipid fatty acids (PLFAs) and neutral lipid fatty acids (NLFAs) content. Soil and root AMF community compositions were determined by DGGE analysis, cloning, sequencing and phylogenetic analyses. The root colonization rate was not significantly affected by different fertilizer regimes. Manure amendment significantly enhanced both AMF hyphal (i.e., 16:1ω5 PLFA) and spore (i.e., 16:1ω5 NLFA) biomass content, while inorganic fertilizer only increased the AMF spore biomass. A total of 10 and 11 Glomeromycota phylotypes were detected in soil and root samples, respectively. Glomus was the dominant genus in both soil and root samples, while Acaulospora genus occurred in roots only. Although the different fertilizers altered soil AMF communities, the root AMF community structure was not significantly altered. Soil pH (. F=. 5.695, P

Although heavy winter mulch and high rate fertilizer application are commonly practiced in intensively managed bamboo (Phyllostachys praecox) plantations, little is known about the effects of these practices on soil microbial activities. Therefore a field study was conducted to investigate the long term intensive management on the development and composition of soil fungal communities. Fungal biomass (fungal phospholipid fatty acid marker), fungal DNA (18S rDNA real-time qPCR) and fungal community composition (culture-independent methods: DGGE, cloning and sequencing) were determined across a bamboo plantation that included seven stand age-classes (1, 4, 6, 8, 10, 12 and 20 years old). Although soil microbial PLFA biomass and fungal DNA abundance were unaffected during the first two years of intensive management, all increased significantly after three years of intensive management. The total microbial PLFA and bacterial PLFA increase linearly (P

Intensive forest management practices, such as fertilization, understory removal and deep tilling, play an important role in improving plant growth in forests through altering nutrient availability and soil structure. However, how such management affects soil microbial community diversity and functions related to nutrient cycling remains largely unknown. In this study, we investigated the responses of soil bacterial community composition and enzyme activities involved in C, N and P cycling to long-term intensive management, and identified the critical determinants that regulated them across a chronosequence of Moso bamboo forests (0, 10, 15, 20 and 25 years of intensive management) in subtropical China. Our results demonstrated that intensive management decreased soil pH and aggregation and increased mineral nutrient contents. Illumina MiSeq sequencing showed that significant (P