Hypersensitivity reaction to pegylated liposomal doxorubicin administration for Mullerian carcinoma in Japanese women.

AIM: PEGylated liposomal doxorubicin (PLD) is a therapeutic agent for gynecological malignancy. Hypersensitivity reaction (HSR) is a major adverse effect that usually disappears after halting administration of PLD. Premedication is usually not necessary before administration of PLD to prevent HSR. Here, we evaluated the frequency of HSR during administration of PLD following premedication in Japanese women. METHODS: We performed PLD administration in 78 patients (386 cycles) between 2013 and 2018. Granisetron hydrochloride and dexamethasone sodium phosphate were administered 30 min before PLD administration. Then, PLD (40 or 30 mg/m2 combined usage with carboplatin) was administered. We retrospectively reviewed the medical records of 78 patients and examined the frequency of HSR. RESULTS: Seven of 78 (9%) patients showed HSR by PLD administration following premedication. One patient showed cardiopulmonary arrest in 13 min after PLD administration (grade 4). The other six patients showed grade 2 HSR. All patients developed HSR in the first course. The incidence of HSR was significantly higher in patients with allergic history than in patients without allergic history (p = 0.0151). CONCLUSIONS: Clinicians should be aware of the potential for HSR in patients administered PLD, particularly those with allergic history and those receiving the first cycle of PLD, even following premedication.

Triggering receptor expressed on myeloid cells 1 and 2 in patients with chronic maxillary sinusitis.

PURPOSE: Chronic sinusitis can result from variable types of immune-mediated process, whose pathogenesis is not fully understood. Triggering receptors expressed on myeloid cells 1 and 2 (TREM-1, TREM-2) are involved in myeloid cell activation enabling these cells to fine-tune the inflammatory response, which may have an impact on subsequent adaptive immunity and may be the key factor in pathogenesis. The aim of the study was to analyse soluble TREM-1 and TREM-2 molecules in maxillary sinus lavage fluid and compare the defined subgroups selected from patients with chronic sinusitis with/without nasal polyps and allergy (asthma and allergic rhinitis). METHODS: The levels of soluble TREM-1 and TREM-2 were measured by Elisa test in a cohort of patients with chronic maxillary sinusitis (n=45). We compared subgroups of patients with nasal polyps (n=33) and allergy (n=25: inclusive of asthma (n=11) and allergic rhinitis (n=14)) with the control group of patients without nasal polyps (n=13), and without allergy (n=21). RESULTS: The study did not prove the difference between subgroups with and without nasal polyps. The levels of soluble TREM-1 did not differ significantly between patients with allergy (asthma and allergic rhinitis) and the control group without allergy (p=0.4804). The levels of soluble TREM-2 were significantly higher in patients with allergy (p=0.0028), asthma (p=0.0103) and allergic rhinitis (p=0.0137) as compared with the control group. CONCLUSION: Our results suggest the role of TREM-2­mediated activation of myeloid cells in chronic sinusitis accompanied by allergy, asthma, and allergic rhinitis (Tab. 6, Ref. 25).

The hypersensitive induced reaction 3 (HIR3) gene contributes to plant basal resistance via an EDS1 and salicylic acid-dependent pathway.

The hypersensitive-induced reaction (HIR) gene family is associated with the hypersensitive response (HR) that is a part of the plant defense system against bacterial and fungal pathogens. The involvement of HIR genes in response to viral pathogens has not yet been studied. We now report that the HIR3 genes of Nicotiana benthamiana and Oryza sativa (rice) were upregulated following rice stripe virus (RSV) infection. Silencing of HIR3s in N. benthamiana resulted in an increased accumulation of RSV RNAs, whereas overexpression of HIR3s in N. benthamiana or rice reduced the expression of RSV RNAs and decreased symptom severity, while also conferring resistance to Turnip mosaic virus, Potato virus X, and the bacterial pathogens Pseudomonas syringae and Xanthomonas oryzae. Silencing of HIR3 genes in N. benthamiana reduced the content of salicylic acid (SA) and was accompanied by the downregulated expression of genes in the SA pathway. Transient expression of the two HIR3 gene homologs from N. benthamiana or the rice HIR3 gene in N. benthamiana leaves caused cell death and an accumulation of SA, but did not do so in EDS1-silenced plants or in plants expressing NahG. The results indicate that HIR3 contributes to plant basal resistance via an EDS1- and SA-dependent pathway.

Attack modes and defence reactions in pathosystems involving Sclerotinia sclerotiorum, Brassica carinata, B. juncea and B. napus.

BACKGROUND AND AIMS: Sclerotinia stem rot (SSR, Sclerotinia sclerotiorum) is a damaging disease of oilseed brassicas world-wide. Host resistance is urgently needed to achieve control, yet the factors that contribute to stem resistance are not well understood. This study investigated the mechanisms of resistance to SSR. METHODS: Stems of 5-week-old Brassica carinata, B. juncea and B. napus of known resistance were infected via filter paper discs impregnated with S. sclerotiorum mycelium under controlled conditions. Transverse sections of the stem and portions of the stem surface were examined using optical and scanning electron microscopy. The association of anatomical features with the severity of disease (measured by mean lesion length) was determined. KEY RESULTS: Several distinct resistance mechanisms were recorded for the first time in these Brassica-pathogen interactions, including hypersensitive reactions and lignification within the stem cortex, endodermis and in tissues surrounding the lesions. Genotypes showing a strong lignification response 72 h post-infection (hpi) tended to have smaller lesions. Extensive vascular invasion by S. sclerotiorum was observed only in susceptible genotypes, especially in the vascular fibres and xylem. Mean lesion length was negatively correlated with the number of cell layers in the cortex, suggesting progress of S. sclerotiorum is impeded by more cell layers. Hyphae in the centre of lesions became highly vacuolate 72 hpi, reflecting an ageing process in S. sclerotiorum hyphal networks that was independent of host resistance. The infection process of S. sclerotiorum was analogous in B. carinata and B. napus. Infection cushions of the highly virulent isolate of S. sclerotiorum MBRS-1 were grouped together in dense parallel bundles, while hyphae in the infection cushions of a less aggressive isolate WW-3 were more diffuse, and this was unaffected by host genotype. CONCLUSIONS: A variety of mechanisms contribute to host resistance against S. sclerotiorum across the three Brassica species. These complex interactions between pathogen and host help to explain variable expressions of resistance often observed in the field.

Mla- and Rom1-mediated control of microRNA398 and chloroplast copper/zinc superoxide dismutase regulates cell death in response to the barley powdery mildew fungus.

• Barley (Hordeum vulgare L.) Mildew resistance locus a (Mla) confers allele-specific interactions with natural variants of the ascomycete fungus Blumeria graminis f. sp. hordei (Bgh), the causal agent of powdery mildew disease. Significant reprogramming of Mla-mediated gene expression occurs upon infection by this obligate biotrophic pathogen. • We utilized a proteomics-based approach, combined with barley mla, required for Mla12 resistance1 (rar1), and restoration of Mla resistance1 (rom1) mutants, to identify components of Mla-directed signaling. • Loss-of-function mutations in Mla and Rar1 both resulted in the reduced accumulation of chloroplast copper/zinc superoxide dismutase 1 (HvSOD1), whereas loss of function in Rom1 re-established HvSOD1 levels. In addition, both Mla and Rom1 negatively regulated hvu-microRNA398 (hvu-miR398), and up-regulation of miR398 was coupled to reduced HvSOD1 expression. Barley stripe mosaic virus (BSMV)-mediated over-expression of both barley and Arabidopsis miR398 repressed accumulation of HvSOD1, and BSMV-induced gene silencing of HvSod1 impeded Mla-triggered H2O2 and hypersensitive reaction (HR) at barley-Bgh interaction sites. • These data indicate that Mla- and Rom1-regulated hvu-miR398 represses HvSOD1 accumulation, influencing effector-induced HR in response to the powdery mildew fungus.

Co-occurrence of Idiopathic Hypereosinophilic Syndrome in End-Stage Renal Disease Patients Undergoing Maintenance Hemodialysis.

Hypereosinophilic syndrome (HES) is defined as the presence of (1) peripheral blood eosinophilia >1.5 x 109/L for at least one month, (2) evidence of eosinophil-mediated organ damage and/or dysfunction, and (3) exclusion of other potential causes of eosinophilia. In hemodialysis patients, HES has been associated with manifestations because of low blood pressure or gastrointestinal symptoms that result in dialysis intolerance. Very few cases of HES co-occurrence in dialysis patients have been reported in the literature, and their clinical characteristics are not fully understood. Here, we report two end-stage renal disease patients diagnosed with idiopathic HES while undergoing maintenance hemodialysis. The first patient presented with unexplained persistent pruritus and intradialytic hypotension, which started 10 minutes after the dialysis session initiation. Hematologic studies revealed hypereosinophilia which remarkably improved on steroid therapy. The second patient was accidentally discovered with asymptomatic persistent hypereosinophilia. His blood counts improved initially on interferon treatment before achieving full remission on steroid therapy. Neither of the two patients reported any history of allergy or atopic manifestations. Our case report sheds light on the possible occurrence of HES in hemodialysis patients which may be confused with other dialysis-related complications. Although steroids remain the mainstay of treatment, the optimal dose and duration of treatment remain unknown.

Drug-Induced Acute Eosinophilic Pneumonia With Pneumomediastinum: An Unusual Presentation.

A 27-year-old female, with no significant past medical history, presented to the casualty department with a two-week history of progressive dyspnea, cough, and fever. She reported that she had recently started taking a non-conventional alternative medication for her irregular menstrual cycles. Chest radiography demonstrated bilateral alveolar opacities, and computed tomography (CT) of the chest revealed bilateral ground-glass opacities and pneumomediastinum. Laboratory testing showed peripheral blood eosinophilia, and bronchoscopy with bronchoalveolar lavage confirmed an elevated eosinophil count. Based on the clinical presentation, radiographic and laboratory findings, and exclusion of other etiologies, a diagnosis of drug-induced eosinophilic lung disease with pneumomediastinum was made. The alternative non-conventional drug was immediately discontinued and the patient was treated with systemic corticosteroids, leading to a rapid improvement in her symptoms and radiographic abnormalities. A repeat CT of the chest after 15 days revealed significant resolution of the ground-glass opacities and complete resolution of pneumomediastinum. This case highlights the importance of thorough medication history and vigilance for potential adverse effects of non-conventional treatments.

A Novel Effector, FSE1, Regulates the Pathogenicity of Fusarium oxysporum f. sp. cubense Tropical Race 4 to Banana by Targeting the MYB Transcription Factor MaEFM-Like.

Phytopathogenic fungi secretes a range of effectors to manipulate plant defenses. Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is a soil-borne pathogen that causes destructive banana wilt disease. Understanding the molecular mechanisms behind Foc TR4 effectors and their regulation of pathogenicity is helpful for developing disease control strategies. In the present study, we identified a novel effector, Fusarium special effector 1 (FSE1), in Foc TR4. We constructed FSE1 knock-out and overexpression mutants and investigated the functions of this effector. In vitro assays revealed that FSE1 was not required for vegetative growth and conidiation of Foc TR4. However, inoculation analysis of banana plantlets demonstrated that knock-out of FSE1 increased the disease index, while overexpression of FSE1 decreased it. Microscope analysis suggested that FSE1 was distributed in the cytoplasm and nuclei of plant cells. Furthermore, we identified an MYB transcription factor, MaEFM-like, as the target of FSE1, and the two proteins physically interacted in the nuclei of plant cells. In addition, Transient expression of MaEFM-like induced cell death in tobacco leaves. Our findings suggest that FSE1 is involved in the pathogenicity of Foc TR4 by targeting MaEFM-like.

Expression of Genes Involved in Anthracnose Resistance in Chili (Capsicum baccatum) 'PBC80'-Derived Recombinant Inbred Lines.

Chili anthracnose has long been a threat to chili production worldwide. Capsicum baccatum 'PBC80' has been identified as a source of resistance to anthracnose. Recently, a QTL for ripe fruit resistance from 'PBC80'-derived RILs was located on chromosome 4 (123 Mb) and contained over 80 defense-related genes. To identify the genes most related to anthracnose resistance, a fine map of the QTL region was developed using single-marker analysis. Nine genes were selected from the new QTL (1.12 Mb) to study their expression after being challenged with Colletotrichum scovillei 'MJ5' in two different RIL genotypes (Resistance/Resistance or R/R and Susceptible/Susceptible or S/S) at 0, 6 and 12 h. Of the nine genes, LYM2, CQW23_09597, CLF, NFXL1, and PR-14 were significantly up-regulated, compared to the control, in the R/R genotype. ERF was up-regulated in both chili genotypes. However, the expression was relatively and constantly low in the S/S genotype. Most up-regulated genes reached the highest peak (2.3-4.5 fold) at 6 h, except for ERF, which had the highest peak at 12 h (6.4 fold). The earliest and highest expressed gene was a pathogen receptor, LYM2.

Kounis Syndrome: Bee Sting-Induced Acute Myocardial Infarction.

Acute coronary syndrome or ST-elevation myocardial infarction that develops as a hypersensitive reaction following exposure to an allergen, such as chemicals or bee or wasp stings, is known as Kounis syndrome (KS). Based on angiographic characteristics, three kinds of KS have been identified. Multiple bee stings typically result in localized allergic reactions and anaphylaxis, but they can also occasionally induce severe systemic toxic reactions. Here, a case of KS in a 50-year-old male presented with swelling on the face and upper limbs and breathing difficulties resulting from bee stings which led to myocardial infarction. The risk of KS should be considered by the physician at the primary level in all situations involving multiple bee bites.

Assessing the Sensitivity of Plasmopara halstedii Isolates to Mefenoxam through Host Responses.

Downy mildew caused by Plasmopara halstedii is responsible for significant economic losses in cultivated sunflowers. Field isolates of sunflower downy mildew resistant to mefenoxam, a previously effective active ingredient against the pathogen, have been found across Europe. The main goal of this study was to assess the sensitivity of P. halstedii isolates to mefenoxam through host responses to infection, such as symptoms measured by disease severity and growth reduction, and host tissue reactions, such as hypersensitive reaction and necrosis of invaded cells. Sunflower seeds were treated with Apron XL 350 FS at the European registered rate (3 mg/kg seeds). Seedlings were inoculated using the soil drench method with eight Hungarian P. halstedii isolates. Disease rates and plant heights were measured twice. Histological examinations of cross-sections of sunflower hypocotyls were performed using a fluorescence microscope. In our study, cluster analyses of sunflowers based on macroscopic and microscopic variables showed differentiation of groups of mefenoxam-treated sunflowers inoculated with different P. halstedii isolates. We first revealed a clear difference in host responses of mefenoxam-treated susceptible sunflowers. In addition, examining tissue reactions (e.g., hypersensitive reaction, necrosis) seems more accurate to estimate the sensitivity of P. halstedii isolates to mefenoxam than macroscopic symptoms.

Removal of Polymer Clips From the Gallbladder Fossa in a Patient With Ehlers-Danlos Syndrome (EDS) to Treat Mast Cell Activation Syndrome (MCAS): A Case Report.

Ehlers-Danlos syndrome (EDS) is a group of hereditary disorders characterized by fragility of connective tissue. Clinical manifestations of the disorder involve the skin, joints, blood vessels, and other internal organs. We report the case of a 29-year-old female suffering from EDS and mast cell activation syndrome (MCAS). Her history includes multiple orthopedic surgeries leading to the worsening of her symptoms. This was determined to be due to medical implants placed during her multiple procedures predisposing her to severe immunological reactions. This case report emphasizes the importance of meticulous surgical intervention when managing patients with EDS.

A Chronological Study on Grapevine Leafroll-Associated Virus 2 in Australia.

Grapevine leafroll disease affects the health status of grapevines worldwide. Most studies in Australia have focused on grapevine leafroll-associated viruses 1 and 3, while little attention has been given to other leafroll virus types, in particular, grapevine leafroll-associated virus 2 (GLRaV-2). A chronological record of the temporal occurrence of GLRaV-2 in Australia since 2001 is reported. From a total of 11,257 samples, 313 tested positive, with an overall incidence of 2.7%. This virus has been detected in 18 grapevine varieties and Vitis rootstocks in different regions of Australia. Most varieties were symptomless on their own roots, while Chardonnay showed a decline in virus-sensitive rootstocks. An isolate of GLRaV-2, on own-rooted Vitis vinifera cv. Grenache, clone SA137, was associated with severe leafroll symptoms after veraison with abnormal leaf necrosis. The metagenomic sequencing results of the virus in two plants of this variety confirmed the presence of GLRaV-2, as well as two inert viruses, grapevine rupestris stem pitting-associated virus (GRSPaV) and grapevine rupestris vein feathering virus (GRVFV). No other leafroll-associated viruses were detected. Among the viroids, hop stunt viroid and grapevine yellow speckle viroid 1 were detected. Of the six phylogenetic groups identified in GLRaV-2, we report the presence of four groups in Australia. Three of these groups were detected in two plants of cv. Grenache, without finding any recombination event. The hypersensitive reaction of certain American hybrid rootstocks to GLRaV-2 is discussed. Due to the association of GLRaV-2 with graft incompatibility and vine decline, the risk from this virus in regions where hybrid Vitis rootstocks are used cannot be overlooked.

A Marine Bacterium with Animal-Pathogen-Like Type III Secretion Elicits the Nonhost Hypersensitive Response in a Land Plant.

Active plant immune response involving programmed cell death called the hypersensitive response (HR) is elicited by microbial effectors delivered through the type III secretion system (T3SS). The marine bacterium Hahella chejuensis contains two T3SSs that are similar to those of animal pathogens, but it was able to elicit HR-like cell death in the land plant Nicotiana benthamiana. The cell death was comparable with the transcriptional patterns of H. chejuensis T3SS-1 genes, was mediated by SGT1, a general regulator of plant resistance, and was suppressed by AvrPto1, a type III-secreted effector of a plant pathogen that inhibits HR. Thus, type III-secreted effectors of a marine bacterium are capable of inducing the nonhost HR in a land plant it has never encountered before. This suggests that plants may have evolved to cope with a potential threat posed by alien pathogen effectors. Our work documents an exceptional case of nonhost HR and provides an expanded perspective for studying plant nonhost resistance.

The apple FERONIA receptor-like kinase MdMRLK2 negatively regulates Valsa canker resistance by suppressing defence responses and hypersensitive reaction.

Valsa canker, caused by the fungus Valsa mali, is one of the most destructive diseases of apple trees in China and other East Asian countries. The plant receptor-like kinase FERONIA is involved in plant cell growth, development, and immunity. However, little is known about the function of FERONIA in apple defence against V. mali. In this study, we found that MdMRLK2 was highly induced by V. mali in twigs of V. mali-susceptible Malus mellana but not in those of the resistant species Malus yunnaensis. 35S:MdMRLK2 apple plants showed compromised resistance relative to wild-type (WT) plants. Further analyses indicated that 35S:MdMRLK2 apple plants had enhanced abscisic acid (ABA) levels and reduced salicylic acid (SA) levels relative to the WT on V. mali infection. MdMRLK2 overexpression also suppressed polyphenol accumulation and inhibited the activities of phenylalanine ammonia-lyase (PAL), ß-1,3-glucanase (GLU), and chitinase (CHT) during V. mali infection. Moreover, MdMRLK2 interacted with MdHIR1, a hypersensitive-induced response protein, and suppressed the MdHIR1-mediated hypersensitive reaction (HR), probably by impairing MdHIR1 self-interaction. Collectively, these findings demonstrate that overexpression of MdMRLK2 compromises Valsa canker resistance, probably by (a) altering ABA and SA levels, (b) suppressing polyphenol accumulation, (c) inhibiting PAL, GLU, and CHT activities, and (d) blocking MdHIR1-mediated HR by disrupting MdHIR1 self-interaction.

Hypersensitive reaction to praziquantel in a clonorchiasis patient.

Praziquantel is the drug of choice for clonorchiasis. Since clonorchiasis is endemic in most river basins, praziquantel has been widely used for 30 years in Korea. A 54-year-old Korean woman suffered from hypersensitive reactions, such as nausea, dyspnea, rash, and urticaria after taking the first dose of praziquantel to treat clonorchiasis. She ingested one dose again and the same symptoms appeared, and she was treated at a clinic with anti-histamines. She tried one more dose with anti-histamines but found the same symptoms. Later, she was found to pass eggs of Clonorchis sinensis and medicated with flubendazole. The hypersensitive reaction to praziquantel is rare but occurs. This is the 5th case report in the world.

Plant Cell Wall as a Key Player During Resistant and Susceptible Plant-Virus Interactions.

The cell wall is a complex and integral part of the plant cell. As a structural element it sustains the shape of the cell and mediates contact among internal and external factors. We have been aware of its involvement in both abiotic (like drought or frost) and biotic stresses (like bacteria or fungi) for some time. In contrast to bacterial and fungal pathogens, viruses are not mechanical destructors of host cell walls, but relatively little is known about remodeling of the plant cell wall in response to viral biotic stress. New research results indicate that the cell wall represents a crucial active component during the plant's response to different viral infections. Apparently, cell wall genes and proteins play key roles during interaction, having a direct influence on the rebuilding of the cell wall architecture. The plant cell wall is involved in both susceptibility as well as resistance reactions. In this review we summarize important progress made in research on plant virus impact on cell wall remodeling. Analyses of essential defensive wall associated proteins in susceptible and resistant responses demonstrate that the components of cell wall metabolism can affect the spread of the virus as well as activate the apoplast- and symplast-based defense mechanisms, thus contributing to the complex network of the plant immune system. Although the cell wall reorganization during the plant-virus interaction remains a challenging task, the use of novel tools and methods to investigate its composition and structure will greatly contribute to our knowledge in the field.

Serum CD203c+ Extracellular Vesicle Serves as a Novel Diagnostic and Prognostic Biomarker for Succinylated Gelatin Induced Perioperative Hypersensitive Reaction.

Background: Perioperative hypersensitivity reaction (HR) is an IgE-FcϵRI-mediated hypersensitivity reaction with degranulation and activation of mast cells and basophils. Several studies have focused on assessing the degranulation and activation of mast cells and basophils to diagnose and predict the prognosis of drug induced HR. However, it is challenging to isolate sufficiently pure mast cells and basophils from human sources to investigate. Effective biomarkers to assess mast cells and basophils activation in vivo could potentially have high diagnostic and prognostic values. In the present study, we investigated EVs pelleted from serum in patients with succinylated gelatin induced HR. Methods: Extracellular vesicles (EVs) were isolated using a total exosome isolation kit and ultracentrifugation, characterized by Western blot, transmission electron microscopy, and nanoparticle tracking analysis. Basophils were isolated from fresh peripheral blood by negative selection using Basophil Isolation Kit II. Human mast cell line was stimulated with IL4. The expression levels of proteins related to the hypersensitive response were evaluated by Western blotting and flow Cytometer. Histamine and tryptase levels were tested using a commercial ELISA kit, and gene expression of inflammatory mediators was evaluated by qRT-PCR. The receiver operating characteristic (ROC) curve was used to evaluate the specificity and sensitivity of biomarker in predicting HR. Results: The concentration of EVs and protein expression level of CD63, FcϵRI, CD203c and tryptase were significantly (p< 0.05) increased in HR samples. The expression level of mast cell/basophil specific CD203c were significantly increased in EVs derived from serum and basophils of HR patients, and the CD203c+-EVs production in mast cells is dramatically increased in the presence of IL4, which positively correlated with histamine, tryptase and inflammatory mediators. Moreover, the ROC curve of EVs concentration and CD203c expression indicated that CD203c+-EVs had a strong diagnostic ability for HR. Conclusion: Serum CD203c+-EVs serves as a novel diagnostic and prognostic biomarker for HR.

Synergistic interaction between the type III secretion system of the endophytic bacterium Pantoea agglomerans DAPP-PG 734 and the virulence of the causal agent of olive knot Pseudomonas savastanoi pv. savastanoi DAPP-PG 722.

The endophytic bacterium Pantoea agglomerans DAPP-PG 734 was previously isolated from olive knots caused by infection with Pseudomonas savastanoi pv. savastanoi DAPP-PG 722. Whole-genome analysis of this P. agglomerans strain revealed the presence of a Hypersensitive response and pathogenicity (Hrp) type III secretion system (T3SS). To assess the role of the P. agglomerans T3SS in the interaction with P. savastanoi pv. savastanoi, we generated independent knockout mutants in three Hrp genes of the P. agglomerans DAPP-PG 734 T3SS (hrpJ, hrpN, and hrpY). In contrast to the wildtype control, all three mutants failed to cause a hypersensitive response when infiltrated in tobacco leaves, suggesting that P. agglomerans T3SS is functional and injects effector proteins in plant cells. In contrast to P. savastanoi pv. savastanoi DAPP-PG 722, the wildtype strain P. agglomerans DAPP-PG 734 and its Hrp T3SS mutants did not cause olive knot disease in 1-year-old olive plants. Coinoculation of P. savastanoi pv. savastanoi with P. agglomerans wildtype strains did not significantly change the knot size, while the DAPP-PG 734 hrpY mutant induced a significant decrease in knot size, which could be complemented by providing hrpY on a plasmid. By epifluorescence microscopy and confocal laser scanning microscopy, we found that the localization patterns in knots were nonoverlapping for P. savastanoi pv. savastanoi and P. agglomerans when coinoculated. Our results suggest that suppression of olive plant defences mediated by the Hrp T3SS of P. agglomerans DAPP-PG 734 positively impacts the virulence of P. savastanoi pv. savastanoi DAPP-PG 722.

Polyamine Oxidation Is Indispensable for Wheat (Triticum aestivum L.) Oxidative Response and Necrotic Reactions during Leaf Rust (Puccinia triticina Eriks.) Infection.

Hydrogen peroxide is a signal and effector molecule in the plant response to pathogen infection. Wheat resistance to Puccinia triticina Eriks. is associated with necrosis triggered by oxidative burst. We investigated which enzyme system dominated in host oxidative reaction to P. triticina infection. The susceptible Thatcher cultivar and isogenic lines with defined resistance genes were inoculated with P. triticina spores. Using diamine oxidase (DAO) and polyamine oxidase (PAO) inhibitors, accumulation of H2O2 was analyzed in the infection sites. Both enzymes participated in the oxidative burst during compatible and incompatible interactions. Accumulation of H2O2 in guard cells, i.e., the first phase of the response, depended on DAO and the role of PAO was negligible. During the second phase, the patterns of H2O2 accumulation in the infection sites were more complex. Accumulation of H2O2 during compatible interaction (Thatcher and TcLr34 line) moderately depended on DAO and the reaction of TcLr34 was stronger than that of Thatcher. Accumulation of H2O2 during incompatible interaction of moderately resistant plants (TcLr24, TcLr25 and TcLr29) was DAO-dependent in TcLr29, while the changes in the remaining lines were not statistically significant. A strong oxidative burst in resistant plants (TcLr9, TcLr19, TcLr26) was associated with both enzymes' activities in TcLr9 and only with DAO in TcLr19 and TcLr26. The results are discussed in relation to other host oxidative systems, necrosis, and resistance level.