A Simulation Study to Reveal the Epidemiology and Aerosol Transmission Characteristics of Botrytis cinerea in Grape Greenhouses.

Most previously studies had considered that plant fungal disease spread widely and quickly by airborne fungi spore. However, little is known about the release dynamics, aerodynamic diameter, and pathogenicity threshold of fungi spore in air of the greenhouse environment. Grape gray mold is caused by Botrytis cinerea; the disease spreads in greenhouses by spores in the air and the spore attaches to the leaf and infects plant through the orifice. In this study, 120 µmol/L propidium monoazide (PMA) were suitable for treatment and quantitation viable spore by quantitative real-time PCR, with a limit detection of 8 spores/mL in spore suspension. In total, 93 strains of B. cinerea with high pathogenicity were isolated and identified from the air samples of grapevines greenhouses by a portable sampler. The particle size of B. cinerea aerosol ranged predominately from 0.65-3.3 µm, accounting for 71.77% of the total amount. The B. cinerea spore aerosols were infective to healthy grape plants, with the lowest concentration that could cause disease being 42 spores/m3. Botrytis cinerea spores collected form six greenhouse in Shandong Province were quantified by PMA-qPCR, with a higher concentration (1182.89 spores/m3) in May and June and a lower concentration in July and August (6.30 spores/m3). This study suggested that spore dispersal in aerosol is an important route for the epidemiology of plant fungal disease, and these data will contribute to the development of new strategies for the effective alleviation and control of plant diseases.

Iron-based materials functionalized with carbon and phosphorus recovered from sludge enhanced the formation of stable minerals to passivate lead and chromium in wastewater and soil.

The bioaccumulation and toxicity of heavy metals are serious threats to human activities and ecological health. The exploitation of environmentally friendly passivated materials is major importance for the remediation of heavy metal contaminated soil. This research developed a new type of environmental functional material with a core-shell structure, which is an iron-based material functionalized with phosphorus and carbon from sludge for heavy metal pollution remediation. The results indicated that the C/P@Fe exhibits excellent heavy metal removal ability, and the maximum removal rates of the two heavy metals in simulated wastewater could reach 100% under optimum reaction conditions. It also effectively converts the labile Cr/Pb into the stable fraction after 28 days of incubation, which increased the maximum residual fraction percentage of Cr and Pb by 32.43% and 160% in soil. Further analysis found that the carbon layer wrapped around the iron base could improve the electron transport efficiency of reducing iron, phosphorus and ferrum could react with heavy metal ions to form stable minerals, such as FeCr2O4, FeO·Cr2O3, Pb5(PO4)3OH, PbCO3, 2PbCO3·Pb(OH)2 and PbS, after reacting with C/P@Fe. The study demonstrated that the Iron-based materials functionalized with carbon and phosphorus from sludge provided a more efficient way to remove heavy metals.

Cross-media migration behavior of antibiotic resistance genes (ARGs) from municipal wastewater treatment systems (MWTSs): Fugitive characteristics, sharing mechanisms, and aerosolization behavior.

The municipal wastewater treatment systems (MWTSs) are the leading enrichment site of antibiotic resistance genes (ARGs), the occurrence of which in sewage and sludge significantly influences the ARGs burden of aerosols. However, the migration behavior and impact factors of ARGs in gas-liquid-solid phase are still unclear. This study collected gas (aerosol), liquid (sewage), and solid (sludge) samples from three MWTSs to explore the cross-media transport behavior of ARGs. The results showed that the main ARGs detected in the solid-gas-liquid phase were consistent, constituting the central antibiotic resistance system of MWTSs. Multidrug resistance genes dominated cross-media transmission (average relative abundance is 42.01 %). Aminocoumarin, fluoroquinolone, and aminoglycoside resistance genes (aerosolization index of 1.260, 1.329, and 1.609, respectively) were prone to migrating from the liquid to gas phase, resulting in long-distance transmission. Environmental factors (mainly temperature and wind speed), water quality index (mainly COD), and heavy metals may be the key factors affecting the trans-media migration of ARGs between the liquid, gas, and solid phase. Based on partial least squares path modeling (PLS-PM), the migration of ARGs in gas phase is primarily influenced by ARGs' aerosolization potential in liquid and solid phase, while heavy metals indirectly influences almost all categories of ARGs. Impact factors aggravated the migration of ARGs in MWTSs through co-selection pressure. This study clarified the key pathways and impact factors that form the cross-media migration behavior of ARGs, which can more specifically control ARGs pollution from different media.

Salt stress altered anaerobic microbial community and carbon metabolism characteristics: The trade-off between methanogenesis and chain elongation.

Discharge of saline organic wastewater is increasing worldwide, yet how salt stress disrupts the microbial community's structure and metabolism in bioreactors has not been systematically investigated. The non-adapted anaerobic granular sludge was inoculated into wastewater with varying salt concentration (ranging from 0% to 5%) to examine the effects of salt stress on the structure and function of the anaerobic microbial community. Result indicated that salt stress had a significant impact on the metabolic function and community structure of the anaerobic granular sludge. Specifically, we observed a notable reduction in methane production in response to all salt stress treatments (r = -0.97, p < 0.01), while an unexpected increase in butyrate production (r = 0.91, p < 0.01) under moderate salt stress (1-3%) with ethanol and acetate as carbon sources. In addition, analysis of microbiome structures and networks demonstrated that as the degree of salt stress increased, the networks exhibited lower connectance and increased compartmentalization. The abundance of interaction partners (methanogenic archaea and syntrophic bacteria) decreased under salt stress. In contrast, the abundance of chain elongation bacteria, specifically Clostridium kluyveri, increased under moderate salt stress (1-3%). As a consequence, the microbial carbon metabolism patterns shifted from cooperative mode (methanogenesis) to independent mode (carbon chain elongation) under moderate salt stress. This study provides evidence that salt stress altered the anaerobic microbial community and carbon metabolism characteristics, and suggests potential guidance for steering the microbiota to promote resource conversion in saline organic wastewater treatment.

Bioremediation system consisted with Leclercia adecarboxylata and nZVI@Carbon/Phosphate for lead immobilization: The passivation mechanisms of chemical reaction and biological metabolism in soil.

Bioremediation is one of the most promising strategies for heavy metal immobilization. A new remediation system was demonstrated in this research, which combined phosphate solubilizing bacteria (PSB) with nZVI@Carbon/Phosphate (nZVI@C/P) composite to remediate lead contaminated soil. Experimental results indicated that the new system (nZVI@C/P + PSB) could effectively convert the labile Pb into the stable fraction after 30 days of incubation, which increased the maximum residual fraction percentage of Pb by 70.58%. The characterization results showed that lead may exist in the forms of Pb5(PO4)3Cl, PbSO4 and 3PbCO3·2Pb(OH)2·H2O in the soil treated with nZVI@C/P + PSB. Meanwhile, soil enzyme activities and Leclercia abundance were enhanced in the treated soil compared with CK during the incubation time. In addition, the specialized functions (e.g. ABC transporters, siderophore metabolism, sulfur metabolism and phosphorus metabolism) in PSB and nZVI@C/P + PSB group were also enhanced. These phenomena proved that the key soil metabolic functions may be maintained and enhanced through the synergistic effect of incubated PSB and nZVI@C/P. The study demonstrated that this new bioremediation system provided feasible way to improve the efficacy for lead contaminated soil remediation.

First report of Coniella vitis causing white rot on Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) in China.

Virginia creeper (Parthenocissus quinquefolia [L.] Planch.) belongs to the genus of Parthenocissus and Vitaceae family, which is very common in vineyards and where wild grape occurs (Bergh et al., 2011). In September of 2021, a severe white rot disease was observed on Virginia creeper around the vineyard of wine grapevine (Cabernet Sauvignon) located in Penglai city (37º 75'38" N, 120º 84'28" E), Shandong province of China. The disease incidence was about 75%, and infected leaf of Virginia creeper exhibited irregular necrotic lesion with brown center, and most lesion occurred on leaf margin, black pycnidia were also observed on the infected leaf at the late stage of infection. To determine the causal agent, symptomatic leaves with typical lesions were cut into small pieces (5 mm × 3 mm), surface sterilized with 75% ethanol for 1 min, followed by three times rinsed in sterile water. Leaf sections were plated onto potato dextrose agar (PDA) medium and incubated at 28°C for 3 days. Totally, five isolates (referred to as JD01, JD07, JD09, JD12 and JD16) were collected and transferred on to fresh PDA medium for incubation at 28°C. Seven days later, colonies on PDA plates had crenulated edges with concentric rings, the upper surface of colonies was mostly flat and white with many pycnidia. The conidia were hyaline at immature and became brown later, spherical or ellipsoid, aseptate, and 7.92 ± 1.20 µm × 5.18 ± 0.61 µm (n=50), length : width ratio is nearly 2. Morphologically, the isolates were identified as Coniella vitis (Chethana et al., 2017). Further to confirm the fungal species, the internal transcribed spacer region (ITS) of the ribosomal RNA gene, large subunit rRNA gene (LSU) and the translation elongation factor 1-alpaha gene (TEF1-α) were amplified using primers ITS1/ ITS4, LR7/ LROR, and TEF1- 728F/ TEF1- 986R (Chethana et al., 2017; Raudabaugh et al., 2018). The amplification products were sequenced and deposited in GenBank database. The sequences were compared to type sequences in GenBank. The results showed that ITS (GenBank accession numbers ON329769, ON329770, ON329771, ON329772 and ON329773), LSU (ON358423，ON358424, ON358425, ON358426 and ON358427) and TEF (ON297671, ON229071, ON229072, ON229073 and ON297672) sequences of the five isolates were 99.66%, 96.90% and 98.79% identical with the sequences data from C. vitis isolates in GeneBank (MFLUCC 18-0093, JZB3700020 and MFLUCC 18-0093, respectively). Furthermore, concatenated sequences of the three genes (ITS, LSU and TEF) were used to conduct a phylogenetic tree using maximum likehood MEGA-X (Raudabaugh et al., 2018). The phylogenetic analysis showed that the five isolates (JD01, JD07, JD09, JD12 and JD16) belong to C. vitis clade among the 41strains of Coniella spp. In the pathogenicity tests, detached leaves of Virginia creeper (1-year-old) were inoculated with mycelia plugs (5 mm diameter) (form 3-day-old of isolate JD07 culture), and control were inoculated with PDA plugs (5 mm diameter). Virginia creeper live plants (1-year-old) were inoculated with conidial suspension (2.5×106 spores/ml) of the isolate JD07 of one week old, and control plants were inoculated with sterile water. All treated Virginia creeper plants (detached leaves) were placed in a greenhouse maintained at 28°C and 95% relative humidity. Virginia creeper plants (detached leaves) inoculated with the conidial suspension (fungal mycelia) had brown lesion on leaves, the disease symptoms were similar to those observed in field. No such symptoms were observed on control plants (detached leaves). The pathogen was reisolated from inoculated Virginia creeper plants and re-identified, thus fulfilling Koch's postulates. C. vitis had been reported to cause grape white rot in China (Chethana et al., 2017). Virginia creeper, as an excellent host of C. vitis, will increase the transmission risk of the pathogens. To our knowledge, this is the first report of C. vitis causing white rot on Virginia creeper, and this finding will provide useful information for developing effective control strategies for white rot disease.

Comparative genomic and functional analyses of Paenibacillus peoriae ZBSF16 with biocontrol potential against grapevine diseases, provide insights into its genes related to plant growth-promoting and biocontrol mechanisms.

Paenibacillus peoriae is a plant growth-promoting rhizobacteria (PGPR) widely distributed in various environments. P. peoriae ZBFS16 was isolated from the wheat rhizosphere and significantly suppressed grape white rot disease caused by Coniella vitis. Here, we present the complete genome sequence of P. peoriae ZBFS16, which consists of a 5.83 Mb circular chromosome with an average G + C content of 45.62%. Phylogenetic analyses showed that ZBFS16 belongs to the genus P. peoriae and was similar to P. peoriae ZF390, P. peoriae HS311 and P. peoriae HJ-2. Comparative analysis with three closely related sequenced strains of P. peoriae identified the conservation of genes involved in indole-3-acetic acid production, phosphate solubilization, nitrogen fixation, biofilm formation, flagella and chemotaxis, quorum-sensing systems, two-component systems, antimicrobial substances and resistance inducers. Meanwhile, in vitro experiments were also performed to confirm these functions. In addition, the strong colonization ability of P. peoriae ZBFS16 was observed in soil, which provides it with great potential for use in agriculture as a PGPR. This study will be helpful for further studies of P. peoriae on the mechanisms of plant growth promotion and biocontrol.

Effect of Pathogenic Fungal Infestation on the Berry Quality and Volatile Organic Compounds of Cabernet Sauvignon and Petit Manseng Grapes.

The effect of pathogenic fungal infestation on berry quality and volatile organic compounds (VOCs) of Cabernet Sauvignon (CS) and Petit Manseng (PM) were investigated by using biochemical assays and gas chromatography-ion mobility spectrometry. No significant difference in diseases-affected grapes for 100-berry weight. The content of tannins and vitamin C decreased significantly in disease-affected grapes, mostly in white rot-affected PM, which decreased by 71.67% and 66.29%. The reduced total flavonoid content in diseases-affected grape, among which the least and most were anthracnose-affected PM (1.61%) and white rot-affected CS (44.74%). All diseases-affected CS had much higher titratable acid, a maximum (18.86 g/100 ml) was observed in the gray mold-affected grapes, while only anthracnose-affected grapes with a higher titratable acid level (21.8 g/100 mL) were observed in PM. A total of 61 VOCs were identified, including 14 alcohols, 13 esters, 12 aldehydes, 4 acids, 4 ketones, 1 ether, and 13 unknown compounds, which were discussed from different functional groups, such as C6-VOCs, alcohols, ester acetates, aldehydes, and acids. The VOCs of CS changed more than that of Petit Manseng's after infection, while gray mold-affected Cabernet Sauvignon had the most change. C6-VOCs, including hexanal and (E)-2-hexenal were decreased in all affected grapes. Some unique VOCs may serve as hypothetical biomarkers to help us identify specific varieties of pathogenic fungal infestation.

Suppression of Grape White Rot Caused by Coniella vitis Using the Potential Biocontrol Agent Bacillus velezensis GSBZ09.

Grape white rot caused by Coniella vitis is prevalent in almost all grapevines worldwide and results in a yield loss of 10-20% annually. Bacillus velezensis is a reputable plant growth-promoting bacterial. Strain GSBZ09 was isolated from grapevine cv. Red Globe (Vitis vinifera) and identified as B. velezensis according to morphological, physiological, biochemical characteristics and a multilocus gene sequence analysis (MLSA) based on six housekeeping genes (16S rRNA, gyrB, rpoD, atpD, rho and pgk). B. velezensis GSBZ09 was screened for antifungal activity against C. vitis under in vitro and in vivo conditions. GSBZ09 presented broad spectrum antifungal activity and produced many extracellular enzymes that remarkably inhibited the mycelial growth and spore germination of C. vitis. Furthermore, GSBZ09 had a high capacity for indole-3-acetic acid (IAA) production, siderophore production, and mineral phosphate solubilization. Pot experiments showed that the application of GSBZ09 significantly decreased the disease index of the grape white rot, directly promoted the growth of grapes, and upregulated defense-related enzymes. Overall, the features of B. velezensis GSBZ09 make it a potential strain for application as a biological control agent against C. vitis.

Conversion of Waste Cooking Oil to Rhamnolipid by a Newly Oleophylic Pseudomonas aeruginosa WO2.

The components of waste cooking oil (WCO) are complex and contain toxic substances, which are difficult to treat biologically. Pseudomonas aeruginosa WO2 was isolated from oily sludge by an anaerobic enrichment-aerobic screening method, which could efficiently utilize WCO and produce rhamnolipid. The effects of nutrients and culture conditions on bacterial growth and lipase activity were investigated to optimize the fermentation of WCO. The results showed that strain WO2 utilized 92.25% of WCO and produced 3.03 g/L of rhamnolipid at 120 h. Compared with inorganic sources, the organic nitrogen source stabilized the pH of fermentation medium, improved lipase activity (up to 19.98 U/mL), and promoted the utilization of WCO. Furthermore, the WO2 strain exhibited inferior utilization ability of the soluble starch contained in food waste, but superior salt stress up to 60 g/L. These unique characteristics demonstrate the potential of Pseudomonas aeruginosa WO2 for the utilization of high-salinity oily organic waste or wastewater.

Cotton CC-NBS-LRR Gene GbCNL130 Confers Resistance to Verticillium Wilt Across Different Species.

Verticillium wilt (VW) is a destructive disease in cotton caused by Verticillium dahliae and has a significant impact on yield and quality. In the absence of safe and effective chemical control, VW is difficult to manage. Thus, at present, developing resistant varieties is the most economical and effective method of controlling Verticillium wilt of cotton. The CC-NBS-LRR (CNL) gene family is an important class of plant genes involved in disease resistance. This study identified 141 GbCNLs in Gossypium barbadense genome, with 37.5% (53 genes) GbCNLs enriched in 12 gene clusters (GC01-GC12) based on gene distribution in the chromosomes. Especially, seven GbCNLs from two largest clusters (GC11 and GC12) were significantly upregulated in the resistant cultivar (Hai No. 7124) and the susceptible (Giza No. 57). Virus-induced gene silencing of GbCNL130 in G. barbadense, one typical gene in the gene cluster 12 (GC12), significantly altered the response to VW, compromising plant resistance to V. dahliae. In contrast, GbCNL130 overexpression significantly increased the resistance to VW in the wild-type Arabidopsis thaliana. Based on our research findings presented here, we conclude that GbCNL130 promotes resistance to VW by activating the salicylic acid (SA)-dependent defense response pathway resulting in strong accumulation of reactive oxygen species and upregulation of pathogenesis-related (PR) genes. In conclusion, our study resulted in the discovery of a new CNL resistance gene in cotton, GbCNL130, that confers resistance to VW across different hosts.

VvXYLP02 confers gray mold resistance by amplifying jasmonate signaling pathway in Vitis vinifera.

Xylogen-like proteins (XYLPs) are essential for plant growth, development, and stress responses. However, little is known about the XYLP gene family in grape and its protective effects against gray mold a destructive disease caused by Botrytis cinerea. We identified and characterized six common XYLPs in the Vitis vinifera genome (VvXYLPs). VvXYLP expression pattern analyses with B. cinerea infection showed that VvXYLP02 was significantly up-regulated in the resistant genotype but down-regulated or only slightly up-regulated in the susceptible genotype. VvXYLP02 overexpression in Arabidopsis thaliana significantly increased resistance to B. cinerea, indicating that the candidate gene has functional importance. Furthermore, JA treatment significantly up-regulated VvXYLP02 expression in V. vinifera. JA-responsive genes were also up-regulated in VvXYLP02 overexpression lines in A. thaliana under B. cinerea inoculation. These findings suggest that VvXYLP02, which is induced by JA upon the pathogen infection, enhances JA dependent response to enforce plant resistance against gray mold disease.

Phosphate functionalized iron based nanomaterials coupled with phosphate solubilizing bacteria as an efficient remediation system to enhance lead passivation in soil.

Bioremediation technology has attracted increasing interest due to it efficient, economical and eco-friendly to apply to heavy metal contaminated soil. This study presents a new biological remediation system with phosphate functionalized iron-based nanomaterials and phosphate solubilizing bacterium strain Leclercia adecarboxylata. Different phosphate content functionalized iron-based nanomaterials were prepared, and nZVI@C/P1 (nP: nFe: nC=1:10:200) with high passivation efficiency was selected to combine with PSB for the remediation experiments. The change in lead fraction and microbial community under five conditions (CK, PSB, nZVI@C, nZVI@C/P1, nZVI@C/P1 + PSB) during 10 days incubation were investigate. The results indicated that nZVI@C/P1 + PSB increased the residual fraction of lead by 93.94% compared with the control group. Meanwhile, inoculation of Leclercia adecarboxylata became the dominant microflora in the soil microbial community during the remediation time, improving the utilization rate of phosphate in nZVI@C/P1 and enhancing the passivation efficiency of lead. Experimental findings demonstrated that combining nZVI@C/P1 with PSB could be considered as an efficient strategy for the lead contaminated soil remediation.

Removal characteristics of dissolved organic matter and membrane fouling in ultrafiltration and reverse osmosis membrane combined processes treating the secondary effluent of wastewater treatment plant.

The widespread implementation of municipal wastewater treatment and reuse must first ensure the safety of reused wastewater. The effluent of the municipal wastewater treatment plant contains a large amount of dissolved organic matter (DOM), which adversely affects the reuse of wastewater. In this study, the ultrafiltration (UF) + reverse osmosis (RO) process was used to treat the secondary effluent from wastewater treatment plants. The relationship between the removal performance, membrane fouling of the UF + RO process, and DOM removal characteristics of influent were studied. The results show that DOM can be removed effectively by UF + RO process. The UF mainly removes DOM with a molecular weight greater than 10 kDa, while RO has a significant removal effect on low-molecular-weight DOM, which mainly causes UF and RO membrane fouling. The UF + RO process has a significant removal rate on fulvic acid, humic acid, tyrosine, and tryptophan, and the order is humic acid > fulvic acid > tyrosine > tryptophan. Fulvic acid contributed the most to the UF membrane fouling, while fulvic acid and protein-like proteins contributed mainly to the RO membrane fouling.

Functional analyses of small secreted cysteine-rich proteins identified candidate effectors in Verticillium dahliae.

Secreted small cysteine-rich proteins (SCPs) play a critical role in modulating host immunity in plant-pathogen interactions. Bioinformatic analyses showed that the fungal pathogen Verticillium dahliae encodes more than 100 VdSCPs, but their roles in host-pathogen interactions have not been fully characterized. Transient expression of 123 VdSCP-encoding genes in Nicotiana benthamiana identified three candidate genes involved in host-pathogen interactions. The expression of these three proteins, VdSCP27, VdSCP113, and VdSCP126, in N. benthamiana resulted in cell death accompanied by a reactive oxygen species burst, callose deposition, and induction of defence genes. The three VdSCPs mainly localized to the periphery of the cell. BAK1 and SOBIR1 (associated with receptor-like protein) were required for the immunity triggered by these three VdSCPs in N. benthamiana. Site-directed mutagenesis showed that cysteine residues that form disulphide bonds are essential for the functioning of VdSCP126, but not VdSCP27 and VdSCP113. VdSCP27, VdSCP113, and VdSCP126 individually are not essential for V. dahliae infection of N. benthamiana and Gossypium hirsutum, although there was a significant reduction of virulence on N. benthamiana and G. hirsutum when inoculated with the VdSCP27/VdSCP126 double deletion strain. These results illustrate that the SCPs play a critical role in the V. dahliae-plant interaction via an intrinsic virulence function and suppress immunity following infection.

New insights of enhanced anaerobic degradation of refractory pollutants in coking wastewater: Role of zero-valent iron in metagenomic functions.

Coking wastewater (CWW) has long been a serious challenge for anaerobic treatment due to its high concentrations of phenolics and nitrogen-containing heterocyclic compounds (NHCs). Herein, we proposed and validated a new strategy of using zero-valent iron (ZVI) to strengthen the anaerobic treatment of CWW. Results showed that COD removal efficiencies was increased by 9.5-13.7% with the assistance of ZVI. GC-MS analysis indicated that the removal of phenolics and NHCs was improved, and the intermediate 2(1H)-Quinolinone of quinoline degradation was further removed by ZVI addition. High-throughput sequencing showed that phenolics and NHCs degraders, such as Levilinea and Sedimentibacter were significantly enriched, and the predicted gene abundance of xenobiotic degradation and its downstream metabolic pathways was also increased by ZVI. Network and redundancy analysis indicated that the decreased oxidation-reduction potential (ORP) by ZVI was the main driver for microbial community succession. This study provided an alternative strategy for strengthening CWW anaerobic treatment.

The Gossypium hirsutum TIR-NBS-LRR gene GhDSC1 mediates resistance against Verticillium wilt.

Improving genetic resistance is a preferred method to manage Verticillium wilt of cotton and other hosts. Identifying host resistance is difficult because of the dearth of resistance genes against this pathogen. Previously, a novel candidate gene involved in Verticillium wilt resistance was identified by a genome-wide association study using a panel of Gossypium hirsutum accessions. In this study, we cloned the candidate resistance gene from cotton that encodes a protein sharing homology with the TIR-NBS-LRR receptor-like defence protein DSC1 in Arabidopsis thaliana (hereafter named GhDSC1). GhDSC1 expressed at higher levels in response to Verticillium wilt and jasmonic acid (JA) treatment in resistant cotton cultivars as compared to susceptible cultivars and its product was localized to nucleus. The transfer of GhDSC1 to Arabidopsis conferred Verticillium resistance in an A. thaliana dsc1 mutant. This resistance response was associated with reactive oxygen species (ROS) accumulation and increased expression of JA-signalling-related genes. Furthermore, the expression of GhDSC1 in response to Verticillium wilt and JA signalling in A. thaliana displayed expression patterns similar to GhCAMTA3 in cotton under identical conditions, suggesting a coordinated DSC1 and CAMTA3 response in A. thaliana to Verticillium wilt. Analyses of GhDSC1 sequence polymorphism revealed a single nucleotide polymorphism (SNP) difference between resistant and susceptible cotton accessions, within the P-loop motif encoded by GhDSC1. This SNP difference causes ineffective activation of defence response in susceptible cultivars. These results demonstrated that GhDSC1 confers Verticillium resistance in the model plant system of A. thaliana, and therefore represents a suitable candidate for the genetic engineering of Verticillium wilt resistance in cotton.

Population genomics demystifies the defoliation phenotype in the plant pathogen Verticillium dahliae.

Verticillium dahliae is a broad host-range pathogen that causes vascular wilts in plants. Interactions between three hosts and specific V. dahliae genotypes result in severe defoliation. The underlying mechanisms of defoliation are unresolved. Genome resequencing, gene deletion and complementation, gene expression analysis, sequence divergence, defoliating phenotype identification, virulence analysis, and quantification of V. dahliae secondary metabolites were performed. Population genomics previously revealed that G-LSR2 was horizontally transferred from the fungus Fusarium oxysporum f. sp. vasinfectum to V. dahliae and is exclusively found in the genomes of defoliating (D) strains. Deletion of seven genes within G-LSR2, designated as VdDf genes, produced the nondefoliation phenotype on cotton, olive, and okra but complementation of two genes restored the defoliation phenotype. Genes VdDf5 and VdDf6 associated with defoliation shared homology with polyketide synthases involved in secondary metabolism, whereas VdDf7 shared homology with proteins involved in the biosynthesis of N-lauroylethanolamine (N-acylethanolamine (NAE) 12:0), a compound that induces defoliation. NAE overbiosynthesis by D strains also appears to disrupt NAE metabolism in cotton by inducing overexpression of fatty acid amide hydrolase. The VdDfs modulate the synthesis and overproduction of secondary metabolites, such as NAE 12:0, that cause defoliation either by altering abscisic acid sensitivity, hormone disruption, or sensitivity to the pathogen.

Factors affecting performance and functional stratification of membrane-aerated biofilms with a counter-diffusion configuration.

Membrane-aerated biofilms (MABs) developed with a novel counter-diffusion configuration in oxygen and substrate supply were examined for the effect of biofilm thickness on the functional activity and microbial community structure of the biofilm with the simultaneous degradation of acetonitrile, and nitrification and denitrification. Results demonstrated that different biofilm thicknesses under different surface loading rates (SLRs) caused substantially varied profiles of the microbial activities with distinct functions in the biofilm. Both thick and thin MABs achieved high-rate performance in terms of acetonitrile removal (>99%), but the performance differed in the removal efficiencies of total nitrogen (TN), which was 1.3 times higher in the thick MAB (85%) than in the thin MAB (36.3%). The specific ammonia-oxidizing rate (SAOR) and the specific acetonitrile-degrading rate (SADR) exhibited similar declining and ascending trends in both the thin and thick MABs, respectively. In contrast, the specific denitrifying rate (SDNR) was relatively uniform at a concentration near the detection limit in the thin MAB but exhibited a hump-shaped variation with the highest rate occurring in an intermediate region in the thick MAB. Microbial community analysis revealed a dramatic shift in the dominant bacteria of the community composition with low diversity across the biofilm. This study suggests that the biofilm thickness developed under SLRs, which controls the mass transfer of oxygen and substrates into biofilms, is an important factor affecting the structural and functional stratification of bacterial populations in a single MAB treating organonitrile wastewater.

Characterization and genome analysis of a butanol-isopropanol-producing Clostridium beijerinckii strain BGS1.

BACKGROUND: One of the main challenges of acetone-butanol-ethanol fermentation is to reduce acetone production with high butanol yield. Converting acetone into isopropanol is an alternative pathway to reduce fermentation by-products in the fermentation broth. Here, we aimed to cultivate a wild-type Clostridium strain with high isopropanol and butanol production and reveal its genome information. RESULTS: Clostridium beijerinckii strain BGS1 was found to be capable of producing 10.21 g/L butanol and 3.41 g/L isopropanol, higher than previously known wild-type isopropanol-butanol-producing Clostridium species. Moreover, culture BGS1 exhibited a broad carbon spectrum utilizing diverse sugars such as arabinose, xylose, galactose, cellobiose, and sucrose, with 9.61 g/L butanol and 2.57 g/L isopropanol generated from 60 g/L sucrose and less amount from other sugars. Based on genome analysis, protein-based sequence of strain BGS1 was closer to C. beijerinckii NCIMB 8052, reaching 90.82% similarity, while compared to C. beijerinckii DSM 6423, the similarity was 89.53%. In addition, a unique secondary alcohol dehydrogenase (sAdhE) was revealed in the genome of strain BGS1, which distinguished it from other Clostridium species. Average nucleotide identity analysis identified strain BGS1 belonging to C. beijerinckii. The transcription profile and enzymatic activity of sAdhE proved its function of converting acetone into isopropanol. CONCLUSIONS: Clostridium beijerinckii strain BGS1 is a potential candidate for industrial isopropanol and butanol production. Its genome provides unique information for genetic engineering of isopropanol-butanol-producing microorganisms.