Translatome analysis in acute ischemic stroke: Astrocytes and microglia exhibit differences in poststroke alternative splicing of expressed transcripts.

Astrocytes and microglia undergo dynamic and complex morphological and functional changes following ischemic stroke, which are instrumental in both inflammatory responses and neural repair. While gene expression alterations poststroke have been extensively studied, investigations into posttranscriptional regulatory mechanisms, specifically alternative splicing (AS), remain limited. Utilizing previously reported Ribo-Tag-seq data, this study analyzed AS alterations in poststroke astrocytes and microglia from young adult male and female mice. Our findings reveal that in astrocytes, compared to the sham group, 109 differential alternative splicing (DAS) events were observed at 4 h poststroke, which increased to 320 at day 3. In microglia, these numbers were 316 and 266, respectively. Interestingly, the disparity between DAS genes and differentially expressed genes is substantial, with fewer than 10 genes shared at both poststroke time points in astrocytes and microglia. Gene ontology enrichment analysis revealed the involvement of these DAS genes in diverse functions, encompassing immune response (Adam8, Ccr1), metabolism (Acsl6, Pcyt2, Myo5a), and developmental cell growth (App), among others. Selective DAS events were further validated by semiquantitative RT-PCR. Overall, this study comprehensively describes the AS alterations in astrocytes and microglia during the hyperacute and acute phases of ischemic stroke and underscores the significance of certain hub DAS events in neuroinflammatory processes.

A Survey of Xylella fastidiosa in the U.S. State of Virginia Reveals Wide Distribution of Both Subspecies fastidiosa and multiplex in Grapevine.

Global travel and trade in combination with climate change are expanding the geographic distribution of plant pathogens. The bacterium Xylella fastidiosa is a prime example. Native to the Americas, it has spread to Europe, Asia, and the Middle East. To assess the risk that pathogen introductions pose to crops in newly invaded areas, it is key to survey their diversity, host range, and disease incidence in relation to climatic conditions where they are already present. We performed a survey of X. fastidiosa in grapevine in Virginia using a combination of quantitative PCR, multilocus sequencing, and metagenomics. We also analyzed samples from deciduous trees with leaf scorch symptoms. X. fastidiosa subspecies fastidiosa was identified in grapevines in all regions of the state, even in Northern Virginia, where the temperature was below -9°C for 10 days per year on average in the years preceding sampling. Unexpectedly, we also found for the first time grapevine samples infected with X. fastidiosa subspecies multiplex (Xfm). The Xfm lineage found in grapevines had been previously isolated from blueberries in the Southeastern United States and was distinct from that found in deciduous trees in Virginia. The obtained results will be important for risk assessment of X. fastidiosa introductions in other parts of the world.

Genotypic and Phenotypic Analyses Show Ralstonia solanacearum Cool Virulence is a Quantitative Trait Not Restricted to "Race 3 biovar 2".

Most Ralstonia solanacearum species complex strains cause bacterial wilts in tropical or subtropical zones, but the group known as Race 3 biovar 2 (R3bv2) is cool virulent and causes potato brown rot at lower temperatures. R3bv2 has invaded potato-growing regions around the world but is not established in the United States. Phylogenetically, R3bv2 corresponds to a subset of the R. solanacearum phylotype IIB clade, but little is known about the distribution of the cool virulence phenotype within phylotype IIB. Therefore, genomes of 76 potentially cool virulent phylotype IIB strains and 30 public genomes were phylogenetically analyzed. A single clonal lineage within the sequevar 1 subclade of phylotype IIB that originated in South America has caused nearly all brown rot outbreaks worldwide. To correlate genotypes with relevant phenotypes, we quantified virulence of ten Ralstonia strains on tomato and potato at both 22°C and 28°C. Cool virulence on tomato did not predict cool virulence on potato. We found that cool virulence is a quantitative trait. Strains in the sequevar 1 pandemic clonal lineage caused the most disease, while other R3bv2 strains were only moderately cool virulent. However, some non-R3bv2 strains were highly cool virulent and aggressively colonized potato tubers. Thus, cool virulence is not consistently correlated with strains historically classified as R3bv2 group. To aid detection of sequevar 1 strains, this group was genomically delimited in the LINbase web server and a sequevar 1 diagnostic primer pair was developed and validated. We discuss implications of these results for the R3bv2 definition.

Formation, immunomodulatory activities, and enhancement of glucosinolates and sulforaphane in broccoli sprouts: a review for maximizing the health benefits to human.

Broccoli sprouts have been considered as functional foods which have received increasing attention because they have been highly prized for glucosinolates, phenolics, and vitamins in particular glucosinolates. One of hydrolysates-sulforaphane from glucoraphanin is positively associated with the attenuation of inflammatory, which could reduce diabetes, cardiovascular and cancer risk. In recent decades, the great interest in natural bioactive components especially for sulforaphane promotes numerous researchers to investigate the methods to enhance glucoraphanin levels in broccoli sprouts and evaluate the immunomodulatory activities of sulforaphane. Therefore, glucosinolates profiles are different in broccoli sprouts varied with genotypes and inducers. Physicochemical, biological elicitors, and storage conditions were widely studied to promote the accumulation of glucosinolates and sulforaphane in broccoli sprouts. These inducers would stimulate the biosynthesis pathway gene expression and enzyme activities of glucosinolates and sulforaphane to increase the concentration in broccoli sprouts. The immunomodulatory activity of sulforaphane was summarized to be a new therapy for diseases with immune dysregulation. The perspective of this review served as a potential reference for customers and industries by application of broccoli sprouts as a functional food and clinical medicine.

Genetically predicted effects of physical activity and sedentary behavior on myasthenia gravis: evidence from mendelian randomization study.

BACKGROUND: Myasthenia gravis (MG) is an autoimmune disorder affecting the neuromuscular junction. Despite the potential benefits of higher physical activity and lower sedentary behavior in MG patients, evidence from observational studies for the effect of physical activity on the risk of MG is limited and inconclusive. METHODS: We employed linkage disequilibrium score (LDSC) regression, two-sample Mendelian randomization (MR), and its multivariable extension analyses (MVMR) to assess the relationship between leisure screen time (LST), moderate-to-vigorous intensity physical activity during leisure time (MVPA) and the risk of MG using genome-wide association studies (GWAS) summary datasets. MR analyses were performed using the inverse-variance-weighted (IVW), weighted-median, and MR-Egger regression. Sensitivity analyses were further performed using alternative instruments to test the robustness of our findings. RESULTS: We found evidence of genetic overlap between LST (rg = 0.113, P = 0.023) and MG, as well as between MVPA (rg=-0.220, P = 0.0001) and MG, using LDSC method. The results of the MR suggested an association between genetic liability to LST and increased risk of MG (IVW OR = 1.609, 95% CI = 1.153 to 2.244; P = 0.005). This association was particularly notable for late-onset MG (IVW OR = 1.698, 95% CI = 1.145 to 2.518; P = 0.008), but not for early-onset MG. Consistent findings were obtained in the MVMR analysis using BMI as covariate (IVW OR = 1.593, 95% CI 1.167 to 2.173, P = 0.003). However, the MR analysis does not support a substantial causal effect of MVPA on the risk of MG. CONCLUSION: Our findings support a causal effect of sedentary behavior as measured by LST on MG, indicating that lack of exercise may play a role in the development of MG. Longitudinal and interventional studies of this association are warranted.

Practical continuous-variable quantum secret sharing using plug-and-play dual-phase modulation.

Continuous-variable quantum secret sharing (CVQSS) allows a legitimate user, i.e., the dealer, to share a string of secret keys with multiple distant users. These users cannot individually recover the dealer's secret key unless they work cooperatively. Although the theoretical security proof of CVQSS has been well established, its practical security and implementation still face challenges. In this paper, we suggest a practical scheme for CVQSS using plug-and-play (P&P) configuration and dual-phase-modulated coherent state (DPMCS). The proposed scheme, called P&P DPM-based CVQSS, waives the necessity that each user has to prepare respective coherent states with their own lasers, thereby eliminating synchronous loopholes caused by different lasers and reducing the complexity of deployment of the user's stations. Moreover, the local oscillator (LO) can be generated locally by the dealer so that the whole CVQSS system could be naturally immune to all LO-aimed attacks. We derive the security bounds for P&P DPM-based CVQSS by properly making most of the existing security analysis techniques of continuous-variable quantum key distribution (CVQKD). In addition, an experimental concept of P&P DPM-based CVQSS is also presented, which can be deemed a guideline for future implementation.

Effect of plasma vitamin C levels on Parkinson's disease and age at onset: a Mendelian randomization study.

BACKGROUND: Until now, epidemiological evidence regarding the association between vitamin C intake (both diet and supplements) and Parkinson's disease (PD) remains inconsistent. Hence, it is necessary to establish the causal link between vitamin C levels and PD, and further develop effective therapies or prevention. METHODS: We selected 11 newly identified plasma vitamin C genetic variants from a large-scale plasma vitamin C GWAS dataset (n = 52,018) as the effective instrumental variables, and extracted their corresponding GWAS summary statistics from PD (33,674 PD cases and 449,056 controls) and PD age at onset (AAO) (n = 28,568). We then performed a Mendelian randomization (MR) study to evaluate the causal association of plasma vitamin C levels with PD and PD AAO using inverse-variance weighted (IVW), the weighted median, MR-Egger, and MR-PRESSO test. RESULTS: We did not observe any significant association between genetically increased vitamin C levels and PD. Interestingly, we found a reduced trend of PD AAO (1.134 years) with 1 SD genetically increased vitamin C levels using IVW (beta = - 1.134, 95% CI: [- 2.515, 0.248], P = 0.108). Importantly, this trend was further successfully verified using both weighted median and MR-Egger. Each 1 SD genetically increased vitamin C levels could reduce PD AAO 1.75 and 2.592 years using weighted median (beta = - 1.750, 95% CI: [- 3.396, - 0.105], P = 0.037) and MR-Egger (beta = - 2.592, 95% CI: [- 4.623, - 0.560], P = 0.012). CONCLUSIONS: We demonstrated the causal association between genetically increased plasma vitamin C levels and reduced PD AAO in people of European descent. Randomized controlled trials are required to clarify whether diet intake or supplement, or both could reduce the AAO of PD.

SERPINA1 gene expression in whole blood links the rs6647 variant G allele to an increased risk of large artery atherosclerotic stroke.

The rs6647 variant G allele in SERPINA1 gene was reported to be associated with the risk of large artery atherosclerotic stroke (LAS), however, the mechanism remains unclear. Here, we performed a functional annotation of the rs6647 variant by using the software HaploReg version 4.1 (HaploReg v4.1). Next, the expression quantitative trait loci (eQTLs) analysis of multiple datasets was conducted for determining the association between the rs6647 and SERPINA1 expression in various tissues. Then, a case-control gene expression analysis was done using two independent ischemic stroke (IS) gene expression datasets. Finally, SERPINA1 expression in whole blood samples from 8 LAS patients and 14 healthy persons were compared. The functional annotation suggested that the rs6647 regulates gene expression in multiple human tissues especially in brain and blood. The eQTLs analysis revealed a significant association of the rs6647 G allele with increased expression of SERPINA1 gene only in whole blood. Compared with the controls, there was an increased expression of SERPINA1 gene in whole blood in both IS patients and LAS patients. SERPINA1 gene expression in whole blood bridges the rs6647 variant G allele with increased LAS risk, providing new insights into the mechanisms underlying role of the rs6647 in determining LAS risk.

Estimating the structure of sarcoplasmic proteins extracted from pork tenderloin thawed by a high-voltage electrostatic field.

The application of high-voltage electrostatic field (HVEF) is a novel method of thawing. To determine if HVEF thawing could lead to sarcoplasmic proteins denaturation, and to provide a theoretical estimation of the structure of the sarcoplasmic proteins, pork tenderloin was thawed by traditional and HVEF methods. The results from protein solubility analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimeter showed that HVEF thawing did not result in more protein denaturation than those thawed under air or running water. From the principal component analysis of FTIR raw spectra (1700-1600 cm-1, Amide I region), we observed some separations of samples with different thawing treatments. It was found that the proportions of α-helix (1650-1640 cm-1 spectral bands in the original data) could lead to the differences on the PC2 axis of score plots.

Breath Qigong Improves Recognition in Seniors With Vascular Cognitive Impairment.

CONTEXT: Vascular cognitive impairment (VCI) or vascular dementia is widely considered to be the second-most-common cause of dementia after Alzheimer's disease, accounting for 20% of cases. Little is known about the effectiveness of breath qigong for seniors suffering from VCI or dementia. OBJECTIVES: For seniors with VCI, the study aimed to compare the benefits of qigong practice, cognitive training, and qigong practice + cognitive training in improving cognitive function, memory, executive function, and daily problem-solving ability. DESIGN: The study was a randomized, controlled pilot study that used a prospective design with repeated measures. SETTING: The study took place at the Tianjin Medical University General Hospital (Tianjin, China). PARTICIPANTS: Participants were 93 patients with VCI at a clinic at the hospital. INTERVENTION: The participants were randomly assigned to 1 of 3 groups: (1) qigong practice, an intervention group; (2) cognitive training, a positive control group; or (3) a combination of qigong practice and cognitive training, an intervention group. Participants received the treatments for 3 mo. OUTCOME MEASURES: All outcome measures were undertaken at baseline and postintervention. The measures included (1) the Montreal cognitive assessment, (2) the Loewenstein occupational therapy cognitive assessment, and (3) the Barthel activities of daily living index. RESULTS: All 3 groups showed significant improvements in general cognitive function, memory, executive function, and daily problem-solving ability (P < .05). CONCLUSION: Qigong practice is an easy and convenient exercise performed at no cost and has the potential to improve the cognitive functions of older adults with mild VCI.

Partially Hydrolyzed Guar Gum Attenuates d-Galactose-Induced Oxidative Stress and Restores Gut Microbiota in Rats.

Partially hydrolyzed guar gum (PHGG) has received considerable attention for its various bioactive functions. The injection of d-galactose can cause aging-related injury which is usually resulted from oxidative stress on tissues and cells. In this study, d-galactose (200 mg/kg/day) was injected into rats, and the protective effects of PHGG (500, 1000, and 1500 mg/kg/day) against oxidative damages, as well as its probiotic functions, were analyzed. The results showed that PHGG treatment at a concentration of 1500 mg/kg/day greatly reduced the levels of lactic acid, nitric oxide, inducible nitric oxide synthase, advanced glycation end products, and increased the telomerase activity, by 7.60%, 9.25%, 12.28%, 14.58%, and 9.01%, respectively. Moreover, PHGG significantly elevated the activities of antioxidant enzymes and decreased the content of malondialdehyde in rat serum and brain. The oxidative damage was also significantly alleviated in the liver and hippocampus and the expressions of brain-derived neurotrophic factor and choline acetyltransferase also increased. Furthermore, PHGG treatment could significantly regulated the expression of sirtuin 1, forkhead box O1, and tumor protein p53 in the hippocampus. It also increased the levels of organic acids and improved the composition of intestinal microbiota. These findings demonstrated that PHGG treatment could effectively alleviate the oxidative damage and dysbacteriosis.

Class I PI3K inhibitor ZSTK474 attenuates experimental autoimmune neuritis by decreasing the frequency of Th1/Th17 cells and reducing the production of proinflammatory cytokines.

The Class I phosphatidylinositol 3-kinase inhibitor, 2-(2-difluoromethy lbenzimidazol-1-yl)-4,6-dimorpholino-1,3,5-triazine (ZSTK474), has anti-inflammatory and immunoregulatory properties. However, whether it can be used to treat Guillain-Barré syndrome (GBS)-a neuroinflammatory disorder-is unknown. We induced experimental autoimmune neuritis (EAN) in Lewis rats, an established model of GBS. Orally administered ZSTK474 decreased neurological deficits in the GBS model, as demonstrated by diminished inflammatory cell infiltration, and ameliorated demyelination of sciatic nerves. Additionally, ZSTK474 decreased the number of Th1/Th17 cells and levels of the proinflammatory cytokines interleukin (IL)-1α, IL-1ß, IL-17, IL-23, interferon-γ, and tumor necrosis factor-α. We propose that the phosphoinositide 3-kinase/AKT/mammalian target of rapamycin complex 1 (PI3K/AKT/mTORC1) pathway likely contributed to the neuroprotective effect of ZSTK474. ZSTK474 effectively decreases the frequency of Th1/Th17 cells, thereby reducing the production of proinflammatory cytokines and successfully alleviating the symptoms of EAN. Thus, the neuroprotective effect of ZSTK474 indicates its potential utility as anti-inflammatory therapy for GBS.

PR-957, a selective inhibitor of immunoproteasome subunit low-MW polypeptide 7, attenuates experimental autoimmune neuritis by suppressing Th17-cell differentiation and regulating cytokine production.

Experimental autoimmune neuritis (EAN) is a CD4+ T-cell-mediated autoimmune inflammatory demyelinating disease of the peripheral nervous system. It has been replicated in an animal model of human inflammatory demyelinating polyradiculoneuropathy, Guillain-Barré syndrome. In this study, we evaluated the therapeutic efficacy of a selective inhibitor of the immunoproteasome subunit, low-MW polypeptide 7 (PR-957) in rats with EAN. Our results showed that PR-957 significantly delayed onset day, reduced severity and shortened duration of EAN, and alleviated demyelination and inflammatory infiltration in sciatic nerves. In addition to significantly regulating expression of the cytokine profile, PR-957 treatment down-regulated the proportion of proinflammatory T-helper (Th)17 cells in sciatic nerves and spleens of rats with EAN. Data presented show the role of PR-957 in the signal transducer and activator of transcription 3 (STAT3) pathway. PR-957 not only decreased expression of IL-6 and IL-23 but also led to down-regulation of STAT3 phosphorylation in CD4+ T cells. Regulation of the STAT3 pathway led to a reduction in retinoid-related orphan nuclear receptor γ t and IL-17 production. Furthermore, reduction of STAT3 phosphorylation may have directly suppressed Th17-cell differentiation. Therefore, our study demonstrates that PR-957 could potently alleviate inflammation in rats with EAN and that it may be a likely candidate for treating Guillain-Barré syndrome.-Liu, H., Wan, C., Ding, Y., Han, R., He, Y., Xiao, J., Hao, J. PR-957, a selective inhibitor of immunoproteasome subunit low-MW polypeptide 7, attenuates experimental autoimmune neuritis by suppressing Th17-cell differentiation and regulating cytokine production.

Programmed Death Ligand 1 Plays a Neuroprotective Role in Experimental Autoimmune Neuritis by Controlling Peripheral Nervous System Inflammation of Rats.

Programmed death 1 (PD-1; CD279), a member of the CD28 family, is an inhibitory receptor on T cells and is responsible for T cell dysfunction in infectious diseases and cancers. The ligand for PD-1, programmed death ligand 1 (PD-L1; also known as B7-H1, CD274), is a member of the B7 family. The engagement of PD-1 with programmed death ligand can downregulate autoreactive T cells that participate in multiple autoimmune diseases. Experimental autoimmune neuritis (EAN) is an animal model of Guillain-Barré syndrome, and the pathogenesis of EAN is mediated principally through T cells and macrophages. In this study, we investigated the effects of PD-L1 in EAN rats. For preventative and therapeutic management, we administered PD-L1, which successfully decreased the severity of EAN; it alleviated the neurologic course of EAN, as well as inhibited the infiltration of inflammatory cells and demyelination of sciatic nerves. Our data revealed that PD-L1 treatment inhibited lymphocyte proliferation and altered T cell differentiation by inducing decreases in IFN-γ+CD4+ Th1 cells and IL-17+CD4+ Th17 cells and increases in IL-4+CD4+ Th2 cells and Foxp3+CD4+ regulatory T cells. The expression levels of p-STAT3 and Foxp3 were significantly different in PD-L1-treated groups compared with the control group. Additionally, PD-L1 regulated the expression of Foxp3 and p-STAT3 in EAN, probably by inhibiting PI3K/AKT/mTOR signaling expression. In summary, PD-L1 is a potentially useful agent for the treatment of EAN because of its anti-inflammatory and neuroprotective effects.

Network Reorganization for Neurophysiological and Behavioral Recovery Following Stroke.

Stroke continues to be the main cause of motor disability worldwide. While rehabilitation has been promised to improve recovery after stroke, efficacy in clinical trials has been mixed. We need to understand the cortical recombination framework to understand how biomarkers for neurophysiological reorganized neurotechnologies alter network activity. Here, we summarize the principles of the movement network, including the current evidence of changes in the connections and function of encephalic regions, recovery from stroke and the therapeutic effects of rehabilitation. Overall, improvements or therapeutic effects in limb motor control following stroke are correlated with the effects of interhemispheric competition or compensatory models of the motor supplementary cortex. This review suggests that future research should focus on cross-regional communication and provide fundamental insights into further treatment and rehabilitation for post-stroke patients.

Transcriptome Analysis Reveals the Mechanisms of Accumulation and Conversion of Folate Derivatives during Germination of Quinoa (Chenopodium quinoa Willd.) Seeds.

Folate was enriched during quinoa germination, while molecular mechanisms were not well understood. In this study, three quinoa varieties were selected for germination, and changes in substrate content and enzyme activity of the folate biosynthesis pathway were monitored. 5-Methyltetrahydrofolate (5-CH3-THF) and 5-formyltetrahydrofolate (5-CHO-THF) were significantly enriched in quinoa sprouts. Among the selected varieties, QL-2 exhibited the lowest content of the oxidation product MeFox and the highest total folate content. Based on transcriptome analysis, the p-ABA branch was found to be crucial for folate accumulation, while the pterin branch served as a key control point for the one carbon pool by folate pathway, which limited further folate biosynthesis. In the one carbon pool by folate pathway, genes CqMTHFR and CqAMT significantly contributed to the enrichment of 5-CH3-THF and 5-CHO-THF. Findings gained here would facilitate the potential application of quinoa sprouts as an alternative strategy for folate supplementation.

Simultaneous improvement of thermostability and maltotriose-forming ability of a fungal α-amylase for bread making by directed evolution.

For applications in food industries, a fungal α-amylase from Malbranchea cinnamomea was engineered by directed evolution. Through two rounds of screening, a mutant α-amylase (mMcAmyA) was obtained with higher optimal temperature (70 °C, 5 °C increase) and better hydrolysis properties (18.6 % maltotriose yield, 2.5-fold increase) compared to the wild-type α-amylase (McAmyA). Site-directed mutations revealed that Threonine (Thr) 226 Serine (Ser) substitution was the main reason for the property evolution of mMcAmyA. Through high cell density fermentation, the highest expression level of Thr226Ser was 3951 U/mL. Thr226Ser was further used for bread baking with a dosage of 1000 U/kg flour, resulting in a 17.8 % increase in specific volume and a 35.6 % decrease in hardness compared to the control. The results were a significant improvement on those of McAmyA. Moreover, the mutant showed better anti-staling properties compared to McAmyA, as indicated by the improved sensory evaluation after 4 days of storage at 4 and 25 °C. These findings provide insights into the structure-function relationship of fungal α-amylase and introduce a potential candidate for bread-making industry.

An EEG motor imagery dataset for brain computer interface in acute stroke patients.

The brain-computer interface (BCI) is a technology that involves direct communication with parts of the brain and has evolved rapidly in recent years; it has begun to be used in clinical practice, such as for patient rehabilitation. Patient electroencephalography (EEG) datasets are critical for algorithm optimization and clinical applications of BCIs but are rare at present. We collected data from 50 acute stroke patients with wireless portable saline EEG devices during the performance of two tasks: 1) imagining right-handed movements and 2) imagining left-handed movements. The dataset consists of four types of data: 1) the motor imagery instructions, 2) raw recording data, 3) pre-processed data after removing artefacts and other manipulations, and 4) patient characteristics. This is the first open dataset to address left- and right-handed motor imagery in acute stroke patients. We believe that the dataset will be very helpful for analysing brain activation and designing decoding methods that are more applicable for acute stroke patients, which will greatly facilitate research in the field of motor imagery-BCI.

The plant pathogen Pseudomonas syringae pv. tomato is genetically monomorphic and under strong selection to evade tomato immunity.

Recently, genome sequencing of many isolates of genetically monomorphic bacterial human pathogens has given new insights into pathogen microevolution and phylogeography. Here, we report a genome-based micro-evolutionary study of a bacterial plant pathogen, Pseudomonas syringae pv. tomato. Only 267 mutations were identified between five sequenced isolates in 3,543,009 nt of analyzed genome sequence, which suggests a recent evolutionary origin of this pathogen. Further analysis with genome-derived markers of 89 world-wide isolates showed that several genotypes exist in North America and in Europe indicating frequent pathogen movement between these world regions. Genome-derived markers and molecular analyses of key pathogen loci important for virulence and motility both suggest ongoing adaptation to the tomato host. A mutational hotspot was found in the type III-secreted effector gene hopM1. These mutations abolish the cell death triggering activity of the full-length protein indicating strong selection for loss of function of this effector, which was previously considered a virulence factor. Two non-synonymous mutations in the flagellin-encoding gene fliC allowed identifying a new microbe associated molecular pattern (MAMP) in a region distinct from the known MAMP flg22. Interestingly, the ancestral allele of this MAMP induces a stronger tomato immune response than the derived alleles. The ancestral allele has largely disappeared from today's Pto populations suggesting that flagellin-triggered immunity limits pathogen fitness even in highly virulent pathogens. An additional non-synonymous mutation was identified in flg22 in South American isolates. Therefore, MAMPs are more variable than expected differing even between otherwise almost identical isolates of the same pathogen strain.

Nonagricultural reservoirs contribute to emergence and evolution of Pseudomonas syringae crop pathogens.

While the existence of environmental reservoirs of human pathogens is well established, less is known about the role of nonagricultural environments in emergence, evolution, and spread of crop pathogens. Here, we analyzed phylogeny, virulence genes, host range, and aggressiveness of Pseudomonas syringae strains closely related to the tomato pathogen P. syringae pv. tomato (Pto), including strains isolated from snowpack and streams. The population of Pto relatives in nonagricultural environments was estimated to be large and its diversity to be higher than that of the population of Pto and its relatives on crops. Ancestors of environmental strains, Pto, and other genetically monomorphic crop pathogens were inferred to have frequently recombined, suggesting an epidemic population structure for P. syringae. Some environmental strains have repertoires of type III-secreted effectors very similar to Pto, are almost as aggressive on tomato as Pto, but have a wider host range than typical Pto strains. We conclude that crop pathogens may have evolved through a small number of evolutionary events from a population of less aggressive ancestors with a wider host range present in nonagricultural environments.