Long-Term Fertilization Strategy Impacts Rhizoctonia solani–Microbe Interactions in Soil and Rhizosphere and Defense Responses in Lettuce

The long-term effects of agricultural management such as different fertilization strategies on soil microbiota and soil suppressiveness against plant pathogens are crucial. Therefore, the suppressiveness of soils differing in fertilization history was assessed using two Rhizoctonia solani isolates and their respective host plants (lettuce, sugar beet) in pot experiments. Further, the effects of fertilization history and the pathogen R. solani AG1-IB on the bulk soil, root-associated soil and rhizosphere microbiota of lettuce were analyzed based on amplicon sequencing of the 16S rRNA gene and ITS2 region. Organic fertilization history supported the spread of the soil-borne pathogens compared to long-term mineral fertilization. The fertilization strategy affected bacterial and fungal community composition in the root-associated soil and rhizosphere, respectively, but only the fungal community shifted in response to the inoculated pathogen. The potential plant-beneficial genus Talaromyces was enriched in the rhizosphere by organic fertilization and presence of the pathogen. Moreover, increased expression levels of defense-related genes in shoots of lettuce were observed in the soil with organic fertilization history, both in the absence and presence of the pathogen. This may reflect the enrichment of potential plant-beneficial microorganisms in the rhizosphere, but also pathogen infestation. However, enhanced defense responses resulted in retarded plant growth in the presence of R. solani (plant growth/defense tradeoff).

Distinct rhizomicrobiota assemblages and plant performance in lettuce grown in soils with different agricultural management histories

A better understanding of factors shaping the rhizosphere microbiota is important for sustainable crop production. We hypothesized that the effect of agricultural management on the soil microbiota is reflected in the assemblage of the rhizosphere microbiota with implications for plant performance. We designed a growth chamber experiment growing the model plant lettuce under controlled conditions in soils of a long-term field experiment with contrasting histories of tillage (mouldboard plough vs cultivator tillage), fertilization intensity (intensive standard nitrogen (N) + pesticides/growth regulators vs extensive reduced N without fungicides/growth regulators), and last standing field crop (rapeseed vs winter wheat). High-throughput sequencing of bacterial and archaeal 16S rRNA genes and fungal ITS2 regions amplified from total community DNA showed that these factors shaped the soil and rhizosphere microbiota of lettuce, however, to different extents among the microbial domains. Pseudomonas and Olpidium were identified as major indicators for agricultural management in the rhizosphere of lettuce. Long-term extensive fertilization history of soils resulted in higher lettuce growth and increased expression of genes involved in plant stress responses compared to intensive fertilization. Our work adds to the increasing knowledge on how soil microbiota can be manipulated by agricultural management practices which could be harnessed for sustainable crop production.

Effect of long-term organic and mineral fertilization strategies on rhizosphere microbiota assemblage and performance of lettuce

Long-term agricultural fertilization strategies gradually change soil properties including the associated microbial communities. Cultivated crops recruit beneficial microbes from the surrounding soil environment via root exudates. In this study, we aimed to investigate the effects of long-term fertilization strategies across field sites on the rhizosphere prokaryotic (Bacteria and Archaea) community composition and plant performance. We conducted growth chamber experiments with lettuce (Lactuca sativa L.) cultivated in soils from two long-term field experiments, each of which compared organic versus mineral fertilization strategies. 16S rRNA gene amplicon sequencing revealed the assemblage of a rhizosphere core microbiota shared in all lettuce plants across soils, going beyond differences in community composition depending on field site and fertilization strategies. The enhanced expression of several plant genes with roles in oxidative and biotic stress signalling pathways in lettuce grown in soils with organic indicates an induced physiological status in plants. Lettuce plants grown in soils with different fertilization histories were visibly free of stress symptoms and achieved comparable biomass. This suggests a positive aboveground plant response to belowground plant-microbe interactions in the rhizosphere. Besides effects of fertilization strategy and field site, our results demonstrate the crucial role of the plant in driving rhizosphere microbiota assemblage.

The Use of Features from Fluorescence, Thermography, and NDVI Imaging to Detect Biotic Stress in Lettuce

Fluorescence, normalized difference vegetation index, and thermal imaging are three frequently used nondestructive methods to detect biotic stress in plants. Due, in part, to the inconsistent results reported in the literature and the lack of measurements on the whole-plant scale, we tested the suitability of a wide variety of variables obtained using these three imaging methods to classify young plants into biotically stressed and nonstressed plants. To this end, we applied the model plant-pathogen system lettuce-Rhizoctonia solani. The relevant data from each image and plant (healthy and diseased) was extracted semiautomatically using sophisticated image processing algorithms. This method enabled us to identify the most appropriate variables via discriminant function and logistic regression analysis: photosystem II maximum quantum yield (Fv/Fm) and fluorescence decline ratio can be used to classify variables with an error ≤0.052. Lettuce seedlings with an Fv/Fm ratio > 0.73 were consistently healthy. In some cases, it was possible to detect infection prior to the appearance of symptoms. Possibilities to transfer the method to horticultural practice are discussed.

Arbuscular Mycorrhiza Alleviates Restrictions to Substrate Water Flow and Delays Transpiration Limitation to Stronger Drought in Tomato

Arbuscular mycorrhizal fungi (AMF) proliferate in soil pores, on the surface of soil particles and affect soil structure. Although modifications in substrate moisture retention depend on structure and could influence plant water extraction, mycorrhizal impacts on water retention and hydraulic conductivity were rarely quantified. Hence, we asked whether inoculation with AMF affects substrate water retention, water transport properties and at which drought intensity those factors become limiting for plant transpiration. Solanum lycopersicum plants were set up in the glasshouse, inoculated or not with Funneliformis mosseae, and grown for 35 days under ample water supply. After mycorrhizal establishment, we harvested three sets of plants, one before (36 days after inoculation) and the second (day 42) and third (day 47) within a sequential drying episode. Sampling cores were introduced into pots before planting. After harvest, moisture retention and substrate conductivity properties were assessed and water retention and hydraulic conductivity models were fitted. A root water uptake model was adopted in order to identify the critical substrate moisture that induces soil derived transpiration limitation. Neither substrate porosity nor saturated water contents were affected by inoculation, but both declined after substrates dried. Drying also caused a decline in pot water capacity and hydraulic conductivity. Plant available water contents under wet (pF 1.8-4.2) and dry (pF 2.5-4.2) conditions increased in mycorrhizal substrates and were conserved after drying. Substrate hydraulic conductivity was higher in mycorrhizal pots before and during drought exposure. After withholding water from pots, higher substrate drying rates and lower substrate water potentials were found in mycorrhizal substrates. Mycorrhiza neither affected leaf area nor root weight or length. Consistently with higher substrate drying rates, AMF restored the plant hydraulic status, and increased plant transpiration when soil moisture declined. The water potential at the root surface and the resistance to water flow in the rhizosphere were restored in mycorrhizal pots although the bulk substrate dried more. Finally, substrates colonized by AMF can be more desiccated before substrate water flux quantitatively limits transpiration. This is most pronounced under high transpiration demands and complies with a difference of over 1,000 hPa in substrate water potential.

Soil type dependent rhizosphere competence and biocontrol of two bacterial inoculant strains and their effects on the rhizosphere microbial community of field-grown lettuce

Rhizosphere competence of bacterial inoculants is assumed to be important for successful biocontrol. Knowledge of factors influencing rhizosphere competence under field conditions is largely lacking. The present study is aimed to unravel the effects of soil types on the rhizosphere competence and biocontrol activity of the two inoculant strains Pseudomonas jessenii RU47 and Serratia plymuthica 3Re4-18 in field-grown lettuce in soils inoculated with Rhizoctonia solani AG1-IB or not. Two independent experiments were carried out in 2011 on an experimental plot system with three soil types sharing the same cropping history and weather conditions for more than 10 years. Rifampicin resistant mutants of the inoculants were used to evaluate their colonization in the rhizosphere of lettuce. The rhizosphere bacterial community structure was analyzed by denaturing gradient gel electrophoresis of 16S rRNA gene fragments amplified from total community DNA to get insights into the effects of the inoculants and R. solani on the indigenous rhizosphere bacterial communities. Both inoculants showed a good colonization ability of the rhizosphere of lettuce with more than 10(6) colony forming units per g root dry mass two weeks after planting. An effect of the soil type on rhizosphere competence was observed for 3Re4-18 but not for RU47. In both experiments a comparable rhizosphere competence was observed and in the presence of the inoculants disease symptoms were either significantly reduced, or at least a non-significant trend was shown. Disease severity was highest in diluvial sand followed by alluvial loam and loess loam suggesting that the soil types differed in their conduciveness for bottom rot disease. Compared to effect of the soil type of the rhizosphere bacterial communities, the effects of the pathogen and the inoculants were less pronounced. The soil types had a surprisingly low influence on rhizosphere competence and biocontrol activity while they significantly affected the bottom rot disease severity.

PVT Measurements on 4-n-Pentyl-4´-Cyano-Biphenyl (5CB) and trans-4-(4´-Octyl-Cyclohexyl)-Benzonitrile (8PCH) up to 300 MPa

Specific volumes are presented for 4-n-pentyl-4´-cyanobiphenyl (5CB) and trans-4-(4´-octyl-cyclo-hexyl)-benzonitrile (8PCH) for temperatures between 300 and 370 K up to 300 MPa. The p,Vm ,T data were determined for the liquid crystalline and isotropic phases, and partly also for the solid phase adjacent to the melting curve. Stable and metastable crystal phases can be distinguished. The density and melting temperature of the metastable form are lower than for the stable one. Volume and enthalpy changes accompanying the phase transitions are reported as well. The p,Vm ,T data allow to calculate the entropy change for a hypothetical transition at constant volume. The molar volumes along the nematic-isotropic phase transition TNI (p) allow to determine the molecular field parameter γ = ∂In TNI /∂ In VNI.

Differential Thermal Analysis and PVT Measurements on 2,2,2-Trichloro-ethanol Under High Pressure

The phase behaviour, the calorimetric and volumetric properties of 2,2,2-trichloro-ethanol (TCE) have been studied with differential thermal analysis (DTA) and pVT measurements in the pressure range 1 atm to 300 MPa and temperatures between 250 K to 355 K. TCE displays a metastable plastic phase (solid I') and a non-plastic solid phase II at atmospheric pressure. At least two pressure-induced solid phases have been detected: a stable plastic phase (solid I') and a non-plastic phase (solid III). There are two sets of triple points: a) 123 MPa and 308 K with the phases solid I, solid II and the liquid, b) 243 MPa and 316 K for solid I, II, III. Furthermore a metastable low-temperature brittle form (solid II') has been found, which transforms to solid I at a considerably lower temperature than solid II. The melting curve of solid I' can be pursued to higher pressures up to 260 MPa. On the other hand, the melting curve of the stable plastic phase solid I can be extrapolated beyond the triple point to pressures below 123 MPa. Volume and enthalpy changes are reported for all phase transitions.

Effect of the soil type on the microbiome in the rhizosphere of field-grown lettuce

The complex and enormous diversity of microorganisms associated with plant roots is important for plant health and growth and is shaped by numerous factors. This study aimed to unravel the effects of the soil type on bacterial communities in the rhizosphere of field-grown lettuce. We used an experimental plot system with three different soil types that were stored at the same site for 10 years under the same agricultural management to reveal differences directly linked to the soil type and not influenced by other factors such as climate or cropping history. Bulk soil and rhizosphere samples were collected 3 and 7 weeks after planting. The analysis of 16S rRNA gene fragments amplified from total community DNA by denaturing gradient gel electrophoresis and pyrosequencing revealed soil type dependent differences in the bacterial community structure of the bulk soils and the corresponding rhizospheres. The rhizosphere effect differed depending on the soil type and the plant growth developmental stage. Despite the soil type dependent differences in the bacterial community composition several genera such as Sphingomonas, Rhizobium, Pseudomonas, and Variovorax were significantly increased in the rhizosphere of lettuce grown in all three soils. The number of rhizosphere responders was highest 3 weeks after planting. Interestingly, in the soil with the highest numbers of responders the highest shoot dry weights were observed. Heatmap analysis revealed that many dominant operational taxonomic units were shared among rhizosphere samples of lettuce grown in diluvial sand, alluvial loam, and loess loam and that only a subset was increased in relative abundance in the rhizosphere compared to the corresponding bulk soil. The findings of the study provide insights into the effect of soil types on the rhizosphere microbiome of lettuce.

Application of the OTSC system for the closure of fistulas, anastomosal leakages and perforations within the gastrointestinal tract

Until recently there has been no technique available which reproducibly and safely allowed endoscopic closures of penetrating defects within the digestive tract. With the new "over the scope clipping system" (OTSC system®), which regarding design and function is similar to a bear-trap, a method is available for the endoscopic closure of fistulas and perforations. Here, we present a series of 10 patients, in whom different penetrating defects within the digestive tract could be closed in 9 of 10 cases successfully by the OTSC system®: fistulas (esophagotracheal, esophagopleural, gastrocutaneous and colovesical), perforations (after mucosectomy, after papillotomy and PEG misplacement) and anastomosal leakages (after gastrotomy and gastrectomy). In another case we demonstrate our first experience with the OTSC system® for the prevention of perforations during deep endoscopic R 0 resection of a T 1(sm1)G1 sigmoideal cancer after initial R 1 resection.

Removal of over the scope clips (OTSC) with an Nd:YAG Laser

Until recently there has been no technique available which reproducibly and safely allows endoscopic closures of penetrating defects within the digestive tract. With the new "over the scope clipping system" (OTSC system), which regarding design and function is similar to a bear-trap, a method is available for the endoscopic closure of fistulas and perforations. The OTSC-systems are designed for permanent placement. However, in the case of misplacement or the need to remove the clip after healing of the defect, a technique for destroying and removing the clip should be available. We demonstrate for the first time the successful removal of the deeply penetrating OTSC system by using the Nd:YAG-Laser in 3 cases: (i) after closure of an oesophageal fistula, (ii) after closure of a perforation of the distal common bile duct in the roof of the papilla and (iii) after clip misplacement in a case of a wide oesophagomediastinal fistula resulting in a severe oesophageal stenosis. Clinically relevant thermal lesions were not observed after the procedure. If clinically necessary, the OTSC-system can be safely removed by the Nd:YAG Laser in centres for interventional endoscopy. Because of the small number of cases the method must still be considered as experimental and requires further validation. This will be possible with the help of a newly established OTSC registry ( www.endodo.de ).

[Gangliocytic paraganglioma--a rare cause of an upper gastrointestinal bleeding]

INTRODUCTION

Gangliocytic paraganglioma is a rare tumour, occurring nearly exclusively in the descending part of the duodenum. It is regarded as a mostly benign tumour but of unknown malignant potential, which rarely metastasises to local lymph nodes or distantly.

CASE REPORT

Here we report on a 62-year-old female patient with a marked microcytic anaemia with a haemoglobin concentration of 3.4 mg/dL. Oesophagogastroduodenoscopy showed an ulcerous periampullary tumour in the duodenum with a diameter of approximately 5 cm. Endoscopic ultrasonography showed no evidence of tumour infiltration of the tunica muscularis and of locoregional lymph node metastasis. Therefore, complete endoscopic resection of the tumour was achieved after ligating the tumour base by an endoloop using a dual channel endoscope. In a second step, the tumour base was resected by endoscopic submucosal dissection (ESD) and revealed no residual tumour. The histological evaluation showed a gangliocytic paranganglioma consisting of three specific cell types: epithelioid cells arranged in typical carcinoid-like patterns, spindle cells wrapped around nests of epithelioid cells and ganglion cells. All cell types expressed neuron-specific enolase (NSE) as a neuroendocrine marker. Synaptophysine was expressed mainly by the epithelioid and ganglion cells while the protein S 100 was expressed mainly by the spindle cells, which surround the epithelioid cell nests as a sustentacular network. The proliferation rate determined by Ki67 staining was only < 5 %.

CONCLUSION

Gangliocytic gangliocytomas of the duodenum can be safely removed by endoscopic submucosal dissection as long as there is no evidence of infiltration of the tunica muscularis or of local lymph node metastasis. Because of the unknown malignant potential, these patients have to be controlled by regular ultrasonographic and endosonographic procedures.

["Endoscopy in a stone quarry"--multiple pigment stones 6 weeks after delivery]

A 29-year-old African woman without any history of diseases was referred to our clinic because of recurrent abdominal pain. 6 weeks earlier she had delivered a healthy baby. Laboratory data revealed hypochromic microcytic anemia, elevated cholestatic liver enzymes, and an elevated bilirubin level of 2.2 mg/dl. Abdominal sonography showed choledocholithiasis. The endoscopic retrograde cholangiography showed the presence of more than 100 small stones in the intra- and extrahepatic bile ducts. An endoscopic papillotomy was performed and multiple small black stones were removed from the bile duct by basket into the duodenum. Because of the hypochromic microcytic anemia, the detection of pigment stones and the ethnic background of the patient we suspected a hemoglobinopathy. Hemoglobin electrophoresis showed 97 % HbC. The molecular genetic analysis revealed a homozygous mutation in codon 6 GAG > AAG for the beta globin chain (HbCC). HbC is a structurally abnormal hemoglobin with typical aggregates and tetragonal crystal formation which results in mild chronic hemolytic anemia. The cholezystectomy after 6 weeks was performed without complications.

A facilitated method for endoscopic interventions at the bile duct after Roux-en-Y reconstruction using double balloon enteroscopy

Endoscopic retrograde cholangiography (ERC) after Roux-en-Y reconstruction and modified BII surgery or duodenopancreatectomy is considerably more difficult than ERC under normal anatomic conditions. If the common bile in the afferent loop cannot be reached by a common lateral-viewing duodenoscope because of excessive intestinal length, it has recently become possible to use double balloon enteroscopy (DBE) for ERC to reach the common bile duct. Cannulating the bile duct via DBE in these postoperative settings remains one of the most difficult ERCP manipulations because of the lack of an Albarran lever and the use of extra long ERCP accessories. Here, we report on a facilitated method for endoscopic interventions at the bile duct in postoperative settings with a long afferent loop using DBE. For facilitation of interventions the enteroscope can be exchanged for a 110-cm-long conventional gastroscope after incision of the overtube in three quarters of its circumference. Care has to be taken that the pressure line for the balloon remains intact. The huge benefit of this facilitated method is the use of standard endoscopic material like guides, catheters and papillotomes.

[Pancreaticomediastinal fistula as a rare cause of recurrent pleural effusions]

A 45-year-old male with chronic alcoholism was transferred to our hospital with progressive dyspnoea, bilateral pleural effusions and ascites. Serum concentrations of lipase and CRP were increased. Pleural effusions recurred despite repeated thoracentesis, antibiotic therapy and total parenteral nutrition. A CT scan of chest and abdomen showed a lipomatous pancreas without signs of necrosis. Endosonography (EUS) demonstrated as signs of chronic pancreatitis an increased lobularity of the parenchyma without calcifications and two small cystic lesions in the pancreatic head. The pleural fluid lipase levels were markedly increased compared to a low lipase concentration in ascites. As an explanation for the pleural effusions ERCP showed a retroperitoneal fistula in the head/body region into the mediastinum and a stenosis of the pancreatic duct in the pancreatic head. For the ascites an inflammatory pathogenesis due to the exacerbation of chronic pancreatitis had to be assumed because the analysis showed an exudate with leukocytosis. After papillotomy via the pancreatic duct a 10 French wide 9 cm long stent was inserted into the pancreatic duct bridging the pancreatic fistula. Within 10 days pleural effusions had completely receded. After three weeks pancreaticography showed a total regression of the fistula and the stent was exchanged. After 6 weeks the pancreatic stent was removed with a lasting remission of the pleural effusions.

[Acute generalized cat scratch disease in myelodysplastic syndrome]

In patients with normal immunity, cat scratch disease typically develop a papule at the portal of entry and no other cutaneous features. A 73 year old male patient with a myelodysplastic syndrome developed generalized petechial, papular and, vasculitic skin lesions in association with cat scratch disease. After the diagnosis was established by identifying the causative organism in a lymph node biopsy, the patient was treated with erythromycin for three weeks resulting in progressive clearance of the skin lesions. Apart from the soluble IL-2 receptor, no other serologic inflammatory parameters were elevated. IgG antibodies against Bartonella henselae and Bartonella quintana increased only slightly during acute exacerbation of the disease, but significantly increased some months later. The diagnosis was established by the positive staining of the lymph node biopsy using the Warthin-Starry stain.

Assessment of satisfaction with the communication process during consultation of cancer patients with potentially curable disease, cancer patients on palliative care, and HIV-positive patients

The aim of this study was to evaluate the attitudes of cancer patients towards the medical interview and to determine their psychosocial satisfaction subsequent to the dialogue. The answers given by patients with curable cancer were compared to those given by cancer patients whose treatment intent was palliative and to the replies of patients infected with the human immunodeficiency virus (HIV), a nonmalignant but also incurable state. The subject population comprised a total of 139 patients. Patients had to complete a questionnaire with a total of 34 items. The answers to the questions were rated on a 5-point scale with response options ranging from 1 to 5 or consisting of true-false statements. Cancer patients, palliative and curative, and HIV-positive patients considered their physicians to be honest (x = 4.34, x = 4.58, and x = 4.30, respectively; p = 0.104), and they emphasized that he/she took enough time answering their questions (x = 4.00, x = 4.30 and x = 4391, respectively; p = 0.12). Cancer patients treated with potentially curable disease were more frequently afraid of being informed about additional diagnostic examinations and about the disclosure of results as compared to cancer patients on palliative care (p < 0.05 for both questions). Patients with HIV-infection considered themselves less informed about the treatment they received as compared to curative cancer patients (x = 3.73 and x = 4.28, respectively; p < 0.046). Only 8.0% of the tumor patients on palliative care, but 63.6% of the HIV-positive patients realized that their medication was given with the objective to relieve symptoms (p < 0.001). When asked about additional goals of treatment, 48% of the palliative cancer patients and 15.1% of the HIV-positive patients checked "cure" (p < 0.002). In conclusion, particularly patients with curable cancer were afraid of information they might receive during the medical interview. Cancer patients considered themselves better informed compared to patients with HIV-infection. This is in significant contrast with the actual, measurable knowledge about their disease in the latter group. It is indeed surprising that only a small minority of incurable cancer patients realized that the goal of the medical care they received was relief of symptoms, the principle objective of palliation.

Campylobacter pylori: prospective analysis of clinical and histological factors associated with colonization of the upper gastrointestinal tract

The association of Campylobacter pylori (C.p.) colonization of the upper gastrointestinal tract with five predefined anamnestic variables, seven symptoms of dyspepsia, and various blindly evaluated histological criteria, was prospectively investigated in a consecutive series of 149 patients submitted to upper gastrointestinal tract endoscopy. Colonization was determined by biopsy urease tests and histological searches. Significant differences (P less than 0.05) between C.p.-positive and C.p.-negative patients were found for smoker status and the frequency of therapy with ulcer-healing drugs (positive association with C.p.) and antibiotics (negative association), but not for any other of the anamnestic data or symptoms. These data were further submitted to stepwise multiple logistic regression analyses. Concerning histological findings, C.p. colonization was significantly associated with the degree of antrum and body gastritis (P less than 0.01), and also with lymphocellular infiltration in antrum and body biopsies and neutrophil cellular grading in gastric antra. We conclude that C.p. colonization of the upper gastrointestinal tract is associated with gastritic change of the antrum and, albeit to a lesser extent, of the body mucosa. However, a specific pattern of symptoms to predict C.p. colonization could not be established.

Comparison of biopsy urease test and histologic examination for detection of campylobacter pylori in duodenal, antral and fundic biopsies

The presence of Campylobacter pylori was investigated in duodenal, antral and fundic biopsies of 149 consecutive patients undergoing upper gastrointestinal tract endoscopy by biopsy urease tests (CLOtest; "CLO test") and histologic examination ("HIST") after modified Giemsa staining. Positive results were obtained rarely in the duodenum (4.7% and 12.8% by CLO test and HIST, respectively), but equally frequently in antral (48.3% and 62.4%) and fundic biopsies (55.0% and 54.4%). Using combined evaluations ("COMB") of both CLO test and HIST results, and disregarding isolated positive histologic grades "1" as C. pylori negative, the detection rates were 6.0, 53.0 and 56.4% in the above order and 63.1% overall at any of the biopsy sites. There was no close correlation between the rapidity of the color conversion of the biochemical test and the microscopic grading of C. pylori density. A positive CLO test in single antral biopsy specimens was an accurate predictor of the presence of C. pylori as compared with HIST (predictive value positive PVpos 0.97), while negative antral BUT results did not rule out C. pylori colonization of the upper GI tract (PVneg 0.52 compared with HIST). An additional negative CLO test from fundic biopsies increases the PVneg to 0.58.