Long-Term Field Application of a Plant Growth-Promoting Rhizobacterial Consortium Suppressed Root-Knot Disease by Shaping the Rhizosphere Microbiota.

Root-knot nematodes (Meloidogyne spp.) are one of the most economically important plant parasitic nematodes, infecting almost all cultivated plants and resulting in severe yield losses every year. Plant growth-promoting rhizobacteria (PGPR) have been extensively used to prevent and control root-knot diseases and increase yield. In this study, the effect of a consortium of three PGPR strains (Bacillus cereus AR156, B. subtilis SM21, and Serratia sp. XY21; hereafter "BBS") on root-knot disease of cucumber was evaluated. The application of BBS significantly reduced the severity of root-knot disease by 56 to 72%, increased yield by 36 to 55%, and improved fruit quality by 14 to 90% and soil properties by 1 to 90% relative to the control in the cucumber fields of the Nanjing suburb, Jiangsu Province, from 2015 to 2018. BBS altered the rhizosphere bacterial community. Compared with the control group, it significantly (false discovery rate, P < 0.05) increased the abundance of 14 bacterial genera that were negatively correlated with disease severity. Additionally, the redundancy analysis suggested that BBS-treated rhizosphere soil samples were dominated by disease-suppressive bacteria, including the genera Iamia, Kutzneria, Salinibacterium, Mycobacterium, Kribbella, Pseudonocardia, Sporichthya, Sphaerisporangium, Actinomadura, Flavisolibacter, Phenylobacterium, Bosea, Hyphomicrobium, Agrobacterium, Sphingomonas, and Nannocystis, which were positively related to total organic carbon, total nitrogen, total organic matter, dissolved organic carbon, [Formula: see text]-N, and available phosphorus contents. This suggests that BBS suppresses root-knot nematodes and improves the soil chemical properties of cucumber by altering the rhizosphere microbial community.

Kurstakin Triggers Multicellular Behaviors in Bacillus cereus AR156 and Enhances Disease Control Efficacy Against Rice Sheath Blight.

Kurstakin is the latest discovered family of lipopeptides secreted by Bacillus spp. In this study, the effects of kurstakin on the direct antagonism, multicellularity, and disease control ability of Bacillus cereus AR156 were explored. An insertion mutation in the nonribosomal peptide synthase responsible for kurstakin synthesis led to a significant reduction of antagonistic ability of AR156 against the plant-pathogenic fungi Rhizoctonia solani, Ascochyta citrullina, Fusarium graminearum, and F. oxysporum f. sp. cubense. The loss of kurstakin synthesis ability significantly impaired the swarming motility of AR156 and reduced biofilm formation and amyloid protein accumulation. Although the loss of kurstakin synthesis ability did not reduce the competitiveness of AR156 under laboratory conditions, the colonization and environmental adaptability of the mutant was significantly weaker than that of wild-type AR156 on rice leaves. The cell surface of wild-type AR156 colonizing the leaf surface was covered by a thick biofilm matrix under a scanning electron microscope, but not the mutant. The colonization ability on rice roots and control efficacy against rice sheath blight disease of the mutant were also impaired. Thus, kurstakin participates in the control of plant diseases by B. cereus AR156 through directly inhibiting the growth of pathogenic fungi and improving long-term environmental adaptability and colonization of AR156 on the host surface by triggering multicellularity. This study explored the multiple functions of kurstakin in plant disease control by B. cereus.

Bacillus-Secreted Oxalic Acid Induces Tomato Resistance Against Gray Mold Disease Caused by Botrytis cinerea by Activating the JA/ET Pathway.

Bacillus spp. are known for their ability to control plant diseases; however, the mechanism of disease control by Bacillus spp. is still unclear. Previously, bacterial organic acids have been implicated in the process of disease suppression. We extracted the total organic acid from Bacillus cereus AR156 culture filtrate and identified oxalic acid (OA) as the programmed cell death-inducing factor. OA strongly suppressed the lesion caused by Botrytis cinerea without significant antagonism against the fungus. Low concentration of OA produced by Bacillus spp. inhibited cell death caused by high concentrations of OA in a concentration- and time-dependent manner. Pretreatment with a low concentration of OA led to higher accumulation of active oxygen-scavenging enzymes in tomato leaves and provoked the expression of defense-related genes. The activation of gene expression relied on the jasmonic acid (JA) signaling pathway but not the salicylic acid (SA) pathway. The disease suppression capacity of OA was confirmed on wild-type tomato and its SA accumulation-deficient line, while the control effect was diminished in JA synthesis-deficient mutant, suggesting that the OA-triggered resistance relied on JA and ethylene (ET) signaling transduction. OA secretion ability was widely distributed among the tested Bacillus strains and the final environmental OA concentration was under strict regulation by a pH-sensitive degradation mechanism. This study provides the first systematic analysis on the role of low-concentration OA secreted and maintained by Bacillus spp. in suppression of gray mold disease and determines the dependence of OA-mediated resistance on the JA/ET signaling pathway. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 "No Rights Reserved" license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2022.

[Suprapubic lipectomy with a "Ω" incision for buried penis in obese adult men].

Objective: To investigate the application of suprapubic lipectomy with a "Ω" incision to removal of the prepubic fat pad for the management of buried penis in obese adult patients. METHODS: We retrospectively analyzed the clinical data on 20 obese adult patients with buried penis treated by suprapubic lipectomy via a "Ω" incision between August 2016 and September 2019. RESULTS: The operations were successfully completed in all the cases, with a mean operation time of 3.7 ± 0.6 hours and an average hospital stay of 8.3 ± 3.3 days. There were no such severe surgery-related complications as hematoma, urethral injury, or fat embolism in any of the cases. Fat liquefaction-related superficial wound infection developed in 1 patient postoperatively, which was cured by combined topical and systemic antibiotic therapy. A 3-month follow-up showed a 95% satisfaction of the patients with the postoperative appearance of the penis and suprapubic incision, but no complications such as ED, abnormal penile sensation, or penile retraction. CONCLUSIONS: Suprapubic lipectomy with a "Ω" incision to remove the prepubic fat pad is an effective surgical approach to the management of buried penis in obese adult males, which is an anatomy-based surgical correction and has the advantages of slight injury, rapid recovery and few complications./.

Staged male genital reconstruction with a local flap and free oral graft: a case report and literature review.

BACKGROUND: Male genital skin loss is a common disease in urology. However, male genital skin loss accompanying a penile urethra defect is rarely reported. Herein, we describe a novel surgical technique using a composite local flap and oral mucosal graft to reconstruct the penis, which may provide a new solution for patients with similar conditions. CASE PRESENTATION: A 36-year-old male with a penile urethra defect and a large area of genital skin loss required urethral reconstruction. The meatus had descended to the penoscrotal junction. This procedure was divided into three stages. The first stage of the surgery involved burying the nude penile shaft beneath the skin of the left anteromedial thigh for coverage of the skin defect. The second stage consisted of releasing the penis and expanding the size of the urethral plate for further urethroplasty. The third stage consisted of reconstruction of the anterior urethra 6 months later. Postoperatively, the patient reported satisfactory voiding. The maximal flow rate (MFR) was 22.2 ml/s with no postvoiding residual urine at the 24-month follow-up visit. No edema, infection, hemorrhage, or cicatricial retraction were observed. The patient's erectile function was satisfactory, and his international index of erectile function-5 score (IIEF-5 score) was 23 at the 24-month follow-up visit. Additionally, the presence of nocturnal penile tumescence demonstrated that he had normal erectile function. CONCLUSIONS: This procedure is an effective surgical option for men with complete foreskin and penile urethra defects. It could also be extended as a treatment strategy when composite local or pedicle transposition flaps and free grafts are needed for specific patients.

Biofilms Positively Contribute to Bacillus amyloliquefaciens 54-induced Drought Tolerance in Tomato Plants.

Drought stress is a major obstacle to agriculture. Although many studies have reported on plant drought tolerance achieved via genetic modification, application of plant growth-promoting rhizobacteria (PGPR) to achieve tolerance has rarely been studied. In this study, the ability of three isolates, including Bacillus amyloliquefaciens 54, from 30 potential PGPR to induce drought tolerance in tomato plants was examined via greenhouse screening. The results indicated that B. amyloliquefaciens 54 significantly enhanced drought tolerance by increasing survival rate, relative water content and root vigor. Coordinated changes were also observed in cellular defense responses, including decreased concentration of malondialdehyde and elevated concentration of antioxidant enzyme activities. Moreover, expression levels of stress-responsive genes, such as lea, tdi65, and ltpg2, increased in B. amyloliquefaciens 54-treated plants. In addition, B. amyloliquefaciens 54 induced stomatal closure through an abscisic acid-regulated pathway. Furthermore, we constructed biofilm formation mutants and determined the role of biofilm formation in B. amyloliquefaciens 54-induced drought tolerance. The results showed that biofilm-forming ability was positively correlated with plant root colonization. Moreover, plants inoculated with hyper-robust biofilm (ΔabrB and ΔywcC) mutants were better able to resist drought stress, while defective biofilm (ΔepsA-O and ΔtasA) mutants were more vulnerable to drought stress. Taken altogether, these results suggest that biofilm formation is crucial to B. amyloliquefaciens 54 root colonization and drought tolerance in tomato plants.

The ClpY-ClpQ protease regulates multicellular development in Bacillus subtilis.

ATP-dependent proteases play essential roles in both protein quality control and the regulation of protein activities in bacteria. ClpYQ (also known as HslVU) is one of several highly conserved ATP-dependent proteases in bacteria. The regulation and biological function of ClpYQ have been well studied in Gram-negative bacteria, but are poorly understood in Gram-positive species. In this study, we showed that in the Gram-positive bacterium Bacillus subtilis, the ΔclpYQ deletion mutant formed early and robust biofilms, while swarming motility was severely impaired. Colonies of the ΔclpYQ mutant were also much less mucoid on agar plates, indicating the loss of the production of secreted γ-poly-dl-glutamic acid (γ-PGA). Global proteomic analysis using isobaric tags for relative and absolute quantification (iTRAQ) confirmed that a number of proteins involved in motility, chemotaxis and the production of γ-PGA were less abundant in the ΔclpYQ mutant. The results from both iTRAQ and Western immunoblotting showed that levels of the biofilm master repressor SinR were modestly reduced in the ΔclpYQ mutant, but probably significantly enough to alter biofilm regulation due to the ultrasensitivity of the expression of biofilm genes to SinR protein levels. Western immunoblotting also showed that the abundance of CodY, whose gene is clustered with clpYQ in the same operon, was not impacted on by ΔclpYQ. Lastly, our results suggested that, unlike in Escherichia coli, ClpYQ does not play an essential role in heat-shock response in both B. subtilis and Bacillus cereus. In conclusion, we propose that the ClpYQ protease is primarily involved in multicellular development in B. subtilis.

Selecting Bacterial Antagonists for Cucurbit Downy Mildew and Developing an Effective Application Method.

To identify new bacterial antagonists for cucurbit downy mildew (CDM) caused by Pseudoperonospora cubensis, 163 bacterial isolates were recovered from different microenvironments of field-grown cucumber plants. In the greenhouse, 19 representative isolates were applied to cucumber plants as a foliar spray (FS); 7 isolates achieved the efficacy over 60% against CDM, with 5 (DS22, HS10, DP14, HP4, and DS57) identified as Bacillus pumilus, B. licheniformis, Enterobacter sp., Bacillus sp., and Stenotrophomonas maltophilia, respectively. Strains DP14, DS22, and HS10 were assessed for their biocontrol effect on naturally occurring CDM in 2-year field trials (2010 and 2011), in which their overall efficacy relative to that of propamocarb was 106.25 to 117.17% with foliar spray plus root drench (FS+RD) but only 70.98 to 84.03% with FS. Coincidently, DP14 and HS10 applied as root drench (RD) alone also significantly reduced CDM. Under field conditions, DP14, DS22, and HS10 all successfully colonized cucumber leaves and the rhizosphere, and also significantly increased fruit yield by 37.60 to 51.03%, as well as nutrient levels. Taken together, Enterobacter sp. DP14, B. licheniformis HS10, and B. pumilus DS22 are plant-growth-promoting rhizobacteria effective in controlling CDM in the field, whose efficacy increased with FS+RD compared with FS alone.

Genome-Wide Investigation of Biofilm Formation in Bacillus cereus.

Bacillus cereus is a soil-dwelling Gram-positive bacterium capable of forming structured multicellular communities, or biofilms. However, the regulatory pathways controlling biofilm formation are less well understood in B. cereus In this work, we developed a method to study B. cereus biofilms formed at the air-liquid interface. We applied two genome-wide approaches, random transposon insertion mutagenesis to identify genes that are potentially important for biofilm formation, and transcriptome analyses by RNA sequencing (RNA-seq) to characterize genes that are differentially expressed in B. cereus when cells were grown in a biofilm-inducing medium. For the first approach, we identified 23 genes whose disruption by transposon insertion led to altered biofilm phenotypes. Based on the predicted function, they included genes involved in processes such as nucleotide biosynthesis, iron salvage, and antibiotic production, as well as genes encoding an ATP-dependent protease and transcription regulators. Transcriptome analyses identified about 500 genes that were differentially expressed in cells grown under biofilm-inducing conditions. One particular set of those genes may contribute to major metabolic shifts, leading to elevated production of small volatile molecules. Selected volatile molecules were shown to stimulate robust biofilm formation in B. cereus Our studies represent a genome-wide investigation of B. cereus biofilm formation.IMPORTANCE In this work, we established a robust method for B. cereus biofilm studies and applied two genome-wide approaches, transposon insertion mutagenesis and transcriptome analyses by RNA-seq, to identify genes and pathways that are potentially important for biofilm formation in B. cereus We discovered dozens of genes and two major metabolic shifts that seem to be important for biofilm formation in B. cereus Our study represents a genome-wide investigation on B. cereus biofilm formation.

[Effects of different medications with tadalafil on erectile dysfunction in males with primary sexual failure].

OBJECTIVE: To evaluate the effects of three different medications with tadalafil on erectile dysfunction (ED) in young men with primary sexual failure. METHODS: This study included 76 male ED patients aged 21－35 years who had primary sexual failure but normal nocturnal penile tumescence and rigidity and failed to respond to psychotherapy. We randomly assigned them to receive oral tadalafil once daily, on demand, or once-daily + on-demand. After 2－3 months of treatment, we evaluated the effects based on the scores of the patients in the five domains of the International Index of Erectile Function (IIEF-5). RESULTS: After medication, all the patients showed significantly increased scores in the four domains of IIEF-5, namely, erectile function, orgasmic function, intercourse satisfaction, and overall satisfaction. The on-demand group achieved even higher scores in erectile and orgasmic functions but a lower score in sexual desire than the once-daily group. However, the patients in the once-daily + on-demand group exhibited more significant improvement than those in the other two in all the five domains. CONCLUSIONS: Once-daily + on-demand medication with tadalafil can significantly enhance the therapeutic effect on psychogenic ED in young men with primary sexual failure.

Transcription factors WRKY70 and WRKY11 served as regulators in rhizobacterium Bacillus cereus AR156-induced systemic resistance to Pseudomonas syringae pv. tomato DC3000 in Arabidopsis.

The activation of both the SA and JA/ETsignalling pathways may lead to more efficient general and broad resistance to Pst DC3000 by non-pathogenic rhizobacteria. However, the mechanisms that govern this simultaneous activation are unclear. Using Arabidopsis as a model system, two transcription factors, WRKY11 and WRKY70, were identified as important regulators involved in Induced Systemic Resistance (ISR) triggered by Bacillus cereus AR156. The results revealed that AR156 treatment significantly stimulated the transcription of WRKY70, but suppressed that of WRKY11 in Arabidopsis leaves. Furthermore, they were shown to be required for AR156 enhancing the activation of cellular defence responses and the transcription level of the plant defence response gene. Overexpression of the two transcription factors in Arabidopsis also showed that they were essential for AR156 to elicit ISR. AR156-triggered ISR was completely abolished in the double mutant of the two transcription factors, but still partially retained in the single mutants, indicating that the regulation of the two transcription factors depend on two different pathways. The target genes of the two transcription factors and epistasis analysis suggested that WRKY11 regulated AR156-triggered ISR through activating the JA signalling pathway, and WRKY70 regulated the ISR through activating the SA signalling pathway. In addition, both WRKY11 and WRKY70 modulated AR156-triggered ISR in a NPR1-dependent manner. In conclusion, WRKY11 and WRKY70 played an important role in regulating the signalling transduction pathways involved in AR156-triggered ISR. This study is the first to illustrate the mechanism by which a single rhizobacterium elicits ISR by simultaneously activating both the SA and JA/ET signalling pathways.

Heterometallic Alkaline Earth-Lanthanide Ba(II)-La(III) Microporous Metal-Organic Framework as Bifunctional Luminescent Probes of Al(3+) and MnO4(.).

In this work a rigid asymmetrical tricarboxylate ligand p-terphenyl-3,4″,5-tricarboxylic acid (H3L) has been employed, and a unique heterometallic alkaline earth-lanthanide microporous luminescent metal-organic framework (MOF) {[Ba3La0.5(µ3-L)2.5(H2O)3(DMF)]·(3DMF)}n (1·3DMF) (DMF = dimethylformamide) has been isolated under solvothermal conditions. Single-crystal X-ray structural analysis demonstrates that 2D inorganic Ba-O-La connectivity can be observed in 1, which are further bridged via rigid terphenyl backbones of L(3-), forming a unique I(2)O(1)-type microporous luminescent framework. A 1D microporous channel with dimensionality of 9.151(3) Å × 10.098(1) Å can be observed along the crystallographic a axis. PXRD patterns have been investigated indicating pure phases of 1. The luminescence explorations demonstrated that 1 exhibits highly selective and sensitive sensing for Al(3+) over other cations with high quenching efficiency Ksv value of 1.445 × 10(4) L·mol(-1) and low detection limit (1.11 µM (S/N = 3)). Meanwhile 1 also exhibits highly selective and sensitive sensing for MnO4(-) over other anions with quenching efficiency Ksv = 7.73 × 10(3) L·mol(-1) and low detection limit (0.28 µM (S/N = 3)). It is noted that, when different concentrations of MnO4(-) solutions (0.5 to 100 µM) were dropped into the suspension of 1, the bright blue luminescence of the suspension observed under UV light can gradually change into pink color, indicating visually luminescent sensing, which makes the detection process of MnO4(-) more convenient in practical. The result also reveals that 1 represents the first example of bifunctional heterometallic alkaline earth-lanthanide MOF-based luminescent probes for selectively detecting Al(3+) and MnO4(-) in the water solutions.

Comparative Transcriptome Analysis between Low- and High-Cadmium-Accumulating Genotypes of Pakchoi (Brassica chinensis L.) in Response to Cadmium Stress.

To reduce cadmium (Cd) pollution of food chains, screening and breeding of low-Cd-accumulating cultivars are the focus of much study. Two previously identified genotypes, a low-Cd-accumulating genotype (LAJK) and a high-Cd-accumulating genotype (HAJS) of pakchoi (Brassica chinesis L.), were stressed by Cd (12.5 µM) for 0 h (T0), 3 h (T3) and 24 h (T24). By comparative transcriptome analysis for root tissue, 3005 and 4343 differentially expressed genes (DEGs) were identified in LAJK at T3 (vs T0) and T24 (vs T3), respectively, whereas 8677 and 5081 DEGs were detected in HAJS. Gene expression pattern analysis suggested a delay of Cd responded transcriptional changes in LAJK compared to HAJS. DEG functional enrichments proposed genotype-specific biological processes coped with Cd stress. Cell wall biosynthesis and glutathione (GSH) metabolism were found to involve in Cd resistance in HAJS, whereas DNA repair and abscisic acid (ABA) signal transduction pathways played important roles in LAJK. Furthermore, the genes participating in Cd efflux such as PDR8 were overexpressed in LAJK, whereas those responsible for Cd transport such as YSL1 were more enhanced in HAJS, exhibiting different Cd transport processes between two genotypes. These novel findings should be useful for molecular assisted screening and breeding of low-Cd-accumulating genotypes for pakchoi.

Biological control of wheat root diseases by the CLP-producing strain Pseudomonas fluorescens HC1-07.

Pseudomonas fluorescens HC1-07, previously isolated from the phyllosphere of wheat grown in Hebei province, China, suppresses the soilborne disease of wheat take-all, caused by Gaeumannomyces graminis var. tritici. We report here that strain HC1-07 also suppresses Rhizoctonia root rot of wheat caused by Rhizoctonia solani AG-8. Strain HC1-07 produced a cyclic lipopeptide (CLP) with a molecular weight of 1,126.42 based on analysis by electrospray ionization mass spectrometry. Extracted CLP inhibited the growth of G. graminis var. tritici and R. solani in vitro. To determine the role of this CLP in biological control, plasposon mutagenesis was used to generate two nonproducing mutants, HC1-07viscB and HC1-07prtR2. Analysis of regions flanking plasposon insertions in HC1-07prtR2 and HC1-07viscB revealed that the inactivated genes were similar to prtR and viscB, respectively, of the well-described biocontrol strain P. fluorescens SBW25 that produces the CLP viscosin. Both genes in HC1-07 were required for the production of the viscosin-like CLP. The two mutants were less inhibitory to G. graminis var. tritici and R. solani in vitro and reduced in ability to suppress take-all. HC1-07viscB but not HC-07prtR2 was reduced in ability to suppress Rhizoctonia root rot. In addition to CLP production, prtR also played a role in protease production.

A Bacillus subtilis sensor kinase involved in triggering biofilm formation on the roots of tomato plants.

The soil bacterium Bacillus subtilis is widely used in agriculture as a biocontrol agent able to protect plants from a variety of pathogens. Protection is thought to involve the formation of bacterial communities - biofilms - on the roots of the plants. Here we used confocal microscopy to visualize biofilms on the surface of the roots of tomato seedlings and demonstrated that biofilm formation requires genes governing the production of the extracellular matrix that holds cells together. We further show that biofilm formation was dependent on the sensor histidine kinase KinD and in particular on an extracellular CACHE domain implicated in small molecule sensing. Finally, we report that exudates of tomato roots strongly stimulated biofilm formation ex planta and that an abundant small molecule in the exudates, (L) -malic acid, was able to stimulate biofilm formation at high concentrations in a manner that depended on the KinD CACHE domain. We propose that small signalling molecules released by the roots of tomato plants are directly or indirectly recognized by KinD, triggering biofilm formation.

Biocontrol of tomato wilt disease by Bacillus subtilis isolates from natural environments depends on conserved genes mediating biofilm formation.

Bacillus subtilis and other Bacilli have long been used as biological control agents against plant bacterial diseases but the mechanisms by which the bacteria confer protection are not well understood. Our goal in this study was to isolate strains of B. subtilis that exhibit high levels of biocontrol efficacy from natural environments and to investigate the mechanisms by which these strains confer plant protection. We screened a total of 60 isolates collected from various locations across China and obtained six strains that exhibited above 50% biocontrol efficacy on tomato plants against the plant pathogen Ralstonia solanacearum under greenhouse conditions. These wild strains were able to form robust biofilms both in defined medium and on tomato plant roots and exhibited strong antagonistic activities against various plant pathogens in plate assays. We show that plant protection by those strains depended on widely conserved genes required for biofilm formation, including regulatory genes and genes for matrix production. We provide evidence suggesting that matrix production is critical for bacterial colonization on plant root surfaces. Finally, we have established a model system for studies of B. subtilis-tomato plant interactions in protection against a plant pathogen.

Rhizocompetence and antagonistic activity towards genetically diverse Ralstonia solanacearum strains--an improved strategy for selecting biocontrol agents.

Bacterial wilt caused by Ralstonia solanacearum is a serious threat for agricultural production in China. Eight soil bacterial isolates with activity against R. solanacearum TM15 (biovar 3) were tested in this study for their in vitro activity towards ten genetically diverse R. solanacearum isolates from China. The results indicated that each antagonist showed remarkable differences in its ability to in vitro antagonize the ten different R. solanacearum strains. Strain XY21 (based on 16S rRNA gene sequencing affiliated to Serratia) was selected for further studies based on its in vitro antagonistic activity and its excellent rhizocompetence on tomato plants. Under greenhouse conditions XY21 mediated biocontrol of tomato wilt caused by seven different R. solanacearum strains ranged from 19 to 70 %. The establishment of XY21 and its effects on the bacterial community in the tomato rhizosphere were monitored by denaturing gradient gel electrophoresis of 16S rRNA gene fragments PCR-amplified from total community DNA. A positive correlation of the in vitro antagonistic activities of XY21 and the actual biocontrol efficacies towards seven genetically different R. solanacearum strains was found and further confirmed by the efficacy of XY21 in controlling bacterial wilt under field conditions.

Evidence for cyclic Di-GMP-mediated signaling in Bacillus subtilis.

Cyclic di-GMP (c-di-GMP) is a second messenger that regulates diverse cellular processes in bacteria, including motility, biofilm formation, cell-cell signaling, and host colonization. Studies of c-di-GMP signaling have chiefly focused on Gram-negative bacteria. Here, we investigated c-di-GMP signaling in the Gram-positive bacterium Bacillus subtilis by constructing deletion mutations in genes predicted to be involved in the synthesis, breakdown, or response to the second messenger. We found that a putative c-di-GMP-degrading phosphodiesterase, YuxH, and a putative c-di-GMP receptor, YpfA, had strong influences on motility and that these effects depended on sequences similar to canonical EAL and RxxxR-D/NxSxxG motifs, respectively. Evidence indicates that YpfA inhibits motility by interacting with the flagellar motor protein MotA and that yuxH is under the negative control of the master regulator Spo0A∼P. Based on these findings, we propose that YpfA inhibits motility in response to rising levels of c-di-GMP during entry into stationary phase due to the downregulation of yuxH by Spo0A∼P. We also present evidence that YpfA has a mild influence on biofilm formation. In toto, our results demonstrate the existence of a functional c-di-GMP signaling system in B. subtilis that directly inhibits motility and directly or indirectly influences biofilm formation.

Geographic Distribution of Trichothecene Chemotypes of the Fusarium graminearum Species Complex in Major Winter Wheat Production Areas of China.

Fusarium head blight, caused by members of the Fusarium graminearum species complex (FGSC), is among the most destructive and economically important diseases of small grain crops, including wheat. To determine the phylogenetic species and mycotoxin (trichothecene) chemotypes of the FGSC in the major winter-wheat-producing areas of China, 530 isolates were collected from diseased wheat during the years 2008, 2009, and 2010, and typed using a polymerase chain reaction-based trichothecene genotype assay. Virulence of isolates with different chemotypes was also compared. Of the 530 isolates typed, 348 were F. asiaticum and 182 were F. graminearum. Subdividing the 530 isolates by the trichothecene predicted to be expressed, 482 were of the deoxynivalenol (DON) chemotype and 48 were nivalenol (NIV). Acetylated derivatives of DON included 3-acetyldeoxynivalenol (3-AcDON; 300 isolates), and 15-acetyldeoxynivalenol (15-AcDON; 182 isolates). Chemotypes of the F. asiaticum isolates were either 3-AcDON or NIV, with 3-AcDON being predominant. F. graminearum isolates were all of the 15-AcDON chemotype. F. asiaticum was the predominant phylogenetic species in the Yangtze River Basin and F. graminearum was dominant in the north of China. Two areas of co-occurrence of trichothecene chemotypes were found. The 3-AcDON and 15-AcDON isolates had similar levels of virulence. The DON isolates were significantly more virulent than those of the NIV. The 3-AcDON and 15-AcDON chemotypes were predominant in the Yangtze River Basin and areas north of the Yangtze River Basin, respectively, and it is suggested that geographic distribution is associated with differences in temperature as well as crop rotation systems.

Metal complexes with chloride and triazole-based ligands: investigation of a well-resolved up-up-down-down (uudd) cyclic water tetramer and X-H...Cl (X = O and C) hydrogen-bonding interactions.

The crystal structure of the title complex, trans-dichloridotetrakis[1-phenyl-3-(1H-1,2,4-triazol-1-yl-κN(4))propan-1-one]copper(II) hexahydrate, [CuCl(2)(C(11)H(11)N(3)O)(4)]·6H(2)O, is isomorphous with that of the corresponding nickel and cobalt compounds. The complex has crystallographic inversion symmetry with the Cu(II) atom on an inversion centre. Each Cu(II) atom is six-coordinated by one N atom from each of the four 1-phenyl-3-(1H-1,2,4-triazol-1-yl)propan-1-one ligands in the equatorial plane and by two chloride ligands in axial positions. The structure includes a centrosymmetric irregular up-up-down-down (uudd) water tetramer cluster and O-H...Cl hydrogen bonds. Intermolecular C-H...Cl hydrogen bonds exist between adjacent molecules, resulting in a three-dimensional supramolecular network.