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Background Cercospora zeina is a foliar pathogen responsible for maize grey leaf spot in southern Africa that negatively impacts maize production. Plants use a variety of chemical and structural mechanisms to defend themselves against invading pathogens such as C. zeina , including the production of secondary metabolites with antimicrobial properties. In maize, a variety of biotic and abiotic stressors induce the accumulation of the terpenoid phytoalexins, zealexins and kauralexins. Results C. zeina -susceptible line displayed pervasive rectangular grey leaf spot lesions, running parallel with the leaf veins in contrast to C. zeina -resistant line that had restricted disease symptoms. Analysis of the transcriptome of both lines indicated that genes involved in primary and secondary metabolism were up-regualted, and although different pathways were prioritized in each line, production of terpenoid compounds were common to both. Targeted phytoalexin analysis revealed that C. zeina- inoculated leaves accumulated zealexins and kauralexins. The resistant line shows a propensity toward accumulation of the kauralexin B series metabolites in response to infection, which contrasts with the susceptible line that preferentially accumulates the kauralexin A series. Kauralexin accumulation was correlated to expression of the kauralexin biosynthetic gene, ZmAn2 and a candidate biosynthetic gene, ZmKSL2 . We report the expression of a putative copalyl diphosphate synthase gene that is induced by C. zeina in the resistant line exclusively. Discussion This study shows that zealexins and kauralexins, and expression of their biosynthetic genes, are induced by C. zeina in both resistant and susceptible germplasm adapted to the southern African climate. The data presented here indicates that different forms of kauralexins accumulate in the resistant and susceptible maize lines in response to C. zeina , with the accumulation of kauralexin B compounds in a resistant maize line and kauralexin A compounds accumulating in the susceptible line.

Access to clean water, one of the United Nation's Sustainable Development Goals, is challenged by an increase in the presence of emerging microbial and other contaminants due to urbanization, among other factors. Traditionally, the presence of indicator microorganisms is determined using culturing methods. However, these classical methods cannot be used to determine the identities of 'unknown' bacteria and is limited to isolating the culturable state of microorganisms. Thus with culturing, the identities of many bacteria, particularly novel or non-culturable, may remain unknown. The use of a DNA-based method, 16S rRNA next-generation sequencing (NGS), can assist with determining the identities of bacterial populations in a water sample. The objective of this 16S rRNA NGS study was to investigate the bacterial community composition and diversity in a range of water sources. Water samples comprising of potable, surface, ground, marine, aquaculture, rain, wetland and swimming bath water matrices were subjected to 16S rRNA NGS using the Illumina 16S rRNA Metagenomics analysis pipeline. Operational taxonomic units were analysed and the identities of bacterial genera determined. In this study, genera of Acinetobacter, Mycobacterium, Pseudomonas, Legionella, Burkholderia, Yersinia, Staphylococcus and Vibrio were spread across the water matrices. Alpha (within sample) and beta (between samples) diversities for each bacterial community within the tested samples were also determined.

Maize is a globally important crop that is affected by fungal diseases causing yield losses annually. One fungus, Fusarium verticillioides, causes the disease Fusarium Ear Rot (FER), which reduces grain quality and produces mycotoxins called fumonisins that are harmful to animals and humans. As chemical fungicides are expensive and have negative environmental effects, the use of biological control agents (BCAs) has become favourable in recent years. A commonly used fungal BCA is Trichoderma spp., which has been effective in reducing disease incidence as well as enhancing crop growth. In this study, T. asperellum was isolated from an African maize line and was shown to significantly inhibit growth of F. verticillioides in an in vitro competition assay.

Phytoplasmas are cell wall-less plant pathogenic bacteria responsible for major crop losses throughout the world. In grapevine they cause grapevine yellows, a detrimental disease associated with a variety of symptoms. The high economic impact of this disease has sparked considerable interest among researchers to understand molecular mechanisms related to pathogenesis. Increasing evidence exist that a class of small non-coding endogenous RNAs, known as microRNAs (miRNAs), play an important role in post-transcriptional gene regulation during plant development and responses to biotic and abiotic stresses. Thus, we aimed to dissect complex high-throughput small RNA sequencing data for the genome-wide identification of known and novel differentially expressed miRNAs, using read libraries constructed from healthy and phytoplasma-infected Chardonnay leaf material. Furthermore, we utilised computational resources to predict putative miRNA targets to explore the involvement of possible pathogen response pathways. We identified multiple known miRNA sequence variants (isomiRs), likely generated through post-transcriptional modifications. Sequences of 13 known, canonical miRNAs were shown to be differentially expressed. A total of 175 novel miRNA precursor sequences, each derived from a unique genomic location, were predicted, of which 23 were differentially expressed. A homology search revealed that some of these novel miRNAs shared high sequence similarity with conserved miRNAs from other plant species, as well as known grapevine miRNAs. The relative expression of randomly selected known and novel miRNAs was determined with real-time RT-qPCR analysis, thereby validating the trend of expression seen in the normalised small RNA sequencing read count data. Among the putative miRNA targets, we identified genes involved in plant morphology, hormone signalling, nutrient homeostasis, as well as plant stress. Our results may assist in understanding the role that miRNA pathways play during plant pathogenesis, and may be crucial in understanding disease symptom development in aster yellows phytoplasma-infected grapevines.

The Arabidopsis constitutive induced resistance 1 (cir1) mutant displays salicylic acid (SA)-dependent constitutive expression of defence genes and enhanced resistance to biotrophic pathogens. To further characterise the role of CIR1 in plant immunity we conducted epistasis analyses with two key components of the SA-signalling branch of the defence network, ENHANCED DISEASE SUSCEPTIBILITY1 (EDS1) and PHYTOALEXIN DEFICIENT4 (PAD4). We demonstrate that the constitutive defence phenotypes of cir1 require both EDS1 and PAD4, indicating that CIR1 lies upstream of the EDS1-PAD4 regulatory node in the immune signalling network. In light of this finding we examined EDS1 expression in cir1 and observed increased protein, but not mRNA levels in this mutant, suggesting that CIR1 might act as a negative regulator of EDS1 via a posttranscriptional mechanism. Finally, as environmental temperature is known to influence the outcome of plant-pathogen interactions, we analysed cir1 plants grown at 18, 22 or 25uC. We found that susceptibility to Pseudomonas syringae pv. tomato (Pst) DC3000 is modulated by temperature in cir1. Greatest resistance to this pathogen (relative to PR-1:LUC control plants) was observed at 18uC, while at 25uC no difference in susceptibility between cir1 and control plants was apparent. The increase in resistance to Pst DC3000 at 18uC correlated with a stunted growth phenotype, suggesting that activation of defence responses may be enhanced at lower temperatures in the cir1 mutant.

Maize (Zea mays L.) is a staple crop providing food security to millions of people in sub Saharan Africa. Fusarium verticillioides, an important fungal pathogen, infects maize causing ‘Fusarium Ear Rot’ disease, which decreases maize kernel yield and the quality of the crop harvested. Currently, no African maize line is completely resistant to infection by F. verticillioides. This study investigated an African maize line, Zea mays CML144, infected with F. verticillioides. Analysis of morphological characteristics showed significant differences between mock-infected and infected plants. RNA-sequencing (RNA-seq) was conducted on plants 14 days post-inoculation to identify differentially expressed genes (DEGs) involved in F. verticillioides infection. Analysis of RNA-seq data revealed DEGs that were both significantly up- and down-regulated in the infected samples compared to the mock-infected control. The maize TPS1 and cytochrome P450 genes were up-regulated, suggesting that kauralexins were involved in the CML144 defense response. This was substantiated by kauralexin analyses, which showed that kauralexins, belonging to class A and B, accumulated in infected maize tissue. Gene ontology terms relating to response to stimulus, chemical stimulus and carbohydrate metabolic processes were enriched, and the genes belonging to these GO-terms were down-regulated. Quantitative real-time PCR was performed on selected DEGs and measurement of phytoalexin accumulation validated the RNA-seq data and GO-analysis results. A comparison of DEGs from this study to DEGs found in F. verticillioides (ITEM 1744) infected susceptible (CO354) and resistant (CO441) maize genotypes in a previous study, matched 18 DEGs with 17 up-regulated and one down-regulated, respectively. This is the first transcriptomic study on the African maize line, CML144, in response to F. verticillioides infection.

Maize is a socially and economically important crop in Africa (and worldwide) that is severely affected by many fungal pathogens. The pathogen Fusarium verticillioides can infect all maize tissue and causes Fusarium ear rot (FER), a disease that greatly reduces quantity and quality of annual maize yields. In response to fungal infection, maize produces kauralexins and zealexins, which are antimicrobial terpenoid phytoalexins that directly reduce the growth of many fungal pathogens including F. verticillioides. This research evaluates the induction of kauralexins and zealexins in F. verticillioides-inoculated sub-tropical maize lines. CML444 (moderately-resistant to FER) and CML144 (susceptible to FER) accumulated both phytoalexin types in seedling roots in response to seed inoculation with F. verticillioides. CML444 control roots also had higher kauralexin levels in comparison to CML144, suggesting that kauralexin accumulation may be primed for rapid up-regulation in CML444 following fungal infection. The an2 maize mutant, which displays reduced expression of the key kauralexin biosynthetic gene ZmAn2, accumulated decreased root levels of kauralexins and zealexins following F. verticillioides inoculation in comparison to wildtype line W22, confirming that both kauralexins and zealexins play a role in the resistance response to seedling disease caused by F. verticillioides.

Lay SummaryAlmost all patients with SLE experience joint problems and arthritis, 12% suffer permanent joint damage. The wide variability in SLE arthritis and the limitations of existing assessment tools make it difficult to identify joint involvement in clinical care and clinical trials. Here we describe preliminary data on comparisons between optical imaging that uses light to pass through the joint and ultrasound evaluations of lupus in affected and unaffected finger joints. OT imaging of 20 SLE patients were evaluated, 8 finger joints/patient were imaged, with a total of 160 images. Optical imaging correlated with ultrasound findings in 160 evaluated fingers affected by lupus arthritis. The system, which will take the form of an ergonomic glove, will allow the investigators to image lupus arthritis, both in the office and at home, to diagnose and monitor arthritis progress.Background/PurposeAlmost all patients with SLE experience joint problems and arthritis, 12% suffer permanent joint damage. The wide variability in SLE arthritis and the limitations of existing assessment tools make it difficult to identify musculoskeletal involvement in clinical care and clinical trials. Identifying lupus arthritis based on physical exam remains challenging. Clinicians need a robust, easy-to-use imaging technique to diagnose and monitor arthritis in SLE. Ultrasound (US) and magnetic resonance (MRI) allow for more objective assessments but are plagued by operator dependence and high cost. With the support of a DoD award, we are developing a prototype imaging system that uses lasers and light detectors to evaluate finger joints in SLE. Here we describe preliminary data on comparisons between optical imaging and US evaluations of affected and unaffected proximal interphalangeal (PIP) joints.Methods20 SLE patients were evaluated, 8 PIP joints (bilateral PIP 2–5)/patient were imaged, with a total of 160 images. A systematic multiplanar grey-scale (GS) and power doppler (PD) examination of PIP joints was performed using the Outcome Measures in Rheumatology (OMERACT) consensus definitions for joint pathologies, and a combined PDGS score was calculated. Immediately after the US, joints were examined using optical imaging. The instrumentation uses a 670nm, 8mW laser with a 1 mm diameter beam modulated at 300 MHz as light source. The laser beam is focused on the dorsal surface of each finger and scans across the PIP joints (as shown in figure 1a). The transmitted light is collected by an intensified charge-coupled device camera and the absorption and scattering distributions inside the finger are reconstructed (figure 1b shows absorption) using a radiative transfer equation model. Amplitude AUC divided by finger thickness (mm) was calculated and is displayed in figure 2.ResultsWhen comparing OT images of a total of 48 PIPs from healthy volunteers and 160 PIPs from SLE patients, an AUC of 0.79 is obtained (figure 3) with corresponding sensitivity and specificity of 77% and 71% respectively.The PDGS scored 34 joints 0, 44 – 1, 20 – 2 and 22 – 3 (120 joints). The absorption and scattering data were obtained from the reconstructed images. Figure 1c shows a cross section through an unaffected joint (PDGS=0) on the left and an affected joint (PDGS=3) on the right. The average absorption coefficient of joints with PDGS = 0 or 1 was 0.52±0.19 cm-1, while joints with PDGS = 2 or 3 the absorption was 0.60±0.19 cm-1, p < 0.05. Similarly, we found that the difference in the scattering coefficients between the two groups was also statistically significant (10.8±1.9 cm-1 versus 11.8±2.1 cm-1, p< 0.01).ConclusionOptical imaging correlated with PDGS findings in 120 evaluated lupus arthritis PIP joints. Further examination of SLE arthritis using the new US OMERACT criteria that includes a tenosynovitis score and MRI will allow for better definitions of PIP arthritis and improve the correlations with optical imaging.The system, which will take the form of an ergonomic glove (figure 4), will allow the investigators to image lupus arthritis, both in the office and at home, to diagnose and monitor arthritis progress. The goal is to create a portable, wearable, imaging device that permits real-time monitoring of SLE arthritis to improve patient care and outcomes.Abstract 616 Figure 1Reconstruction of absorption and scattering distributionsAbstract 616 Figure 2Boxplot of Amplitude AUC divided by finger thicknessAbstract 616 Figure 3ROC CurveAbstract 616 Figure 4OT Glove

The ZaP-HD Flow Z-Pinch device has shown that sheared-flow can stabilize a plasma in a simple Z pinch configuration for times well over that of a static Z pinch. The plasma is stabilized when the shear flow passes the threshold of dVz/dr ≥ 0.1kVA mitigating the 'kink' instability. The ZaP-HD research project shows promise as both a compact fusion device and as a hypothetical in-space propulsion device. Impurity line radiation from the plasma allows for noninvasive spectroscopic techniques that can provide measurements for various plasma parameters of interest. Time-resolved spectroscopy measurements have been taken on the device in the past, however a new setup with a different high speed camera is used, resulting in measurements with over twice the spatial resolution. Ion Doppler spectroscopy (IDS) is used to measure temperature and velocity of carbon III ions in the plasma. Improved signal due to erosion of the graphite nose cone increases the amount of data collected, allowing for a more complete picture of the pinch behavior over the plasma lifetime. Sheared-flow passing the threshold for stability is found for much of the pulse duration with speeds up to 150 km/s and temperatures up to 500 eV. Time resolved temperature and velocity profiles indicate plasma reflecting off the end wall and propagating upstream as a stagnation wave, causing jump conditions comparable to that of a normal shock in the plasma. An upper limit of thruster performance is found using IDS data in conjunction with typical plasma parameters to yield an effective thrust of 0.216 N and specific impulse of 5.76 x 104 s.

In order to identify components of the defense signaling network engaged following attempted pathogen invasion, we generated a novel PR-1∷luciferase (LUC) transgenic line that was deployed in an imaging-based screen to uncover defense-related mutants. The recessive mutant designated cir1 exhibited constitutive expression of salicylic acid (SA), jasmonic acid (JA)/ethylene, and reactive oxygen intermediate-dependent genes. Moreover, this mutation conferred resistance against the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 and a virulent oomycete pathogen Peronospora parasitica Noco2. Epistasis analyses were undertaken between cir1 and mutants that disrupt the SA (npr1, nahG), JA (jar1), and ethylene (ET) (ein2) signaling pathways. While resistance against both P. syringae pv. tomato DC3000 and Peronospora parasitica Noco2 was partially reduced by npr1, resistance against both of these pathogens was lost in an nahG genetic background. Hence, cir1-mediated resistance is established via NPR1-dependent and -independent signaling pathways and SA accumulation is essential for the function of both pathways. While jar1 and ein2 reduced resistance against P. syringae pv. tomato DC3000, these mutations appeared not to impact cir1-mediated resistance against Peronospora parasitica Noco2. Thus, JA and ET sensitivity are required for cir1-mediated resistance against P. syringae pv. tomato DC3000 but not Peronospora parasitica Noco2. Therefore, the cir1 mutation may define a negative regulator of disease resistance that operates upstream of SA, JA, and ET accumulation.