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Svx proteins are virulence factors secreted by phytopathogenic bacteria of the Pectobacterium genus into the host plant cell wall. Svx-encoding genes are present in almost all species of the soft rot Pectobacteriaceae (Pectobacterium and Dickeya genera). The Svx of P. atrosepticum (Pba) has been shown to be a gluzincin metallopeptidase that presumably targets plant extensins, proteins that contribute to plant cell wall rigidity and participate in cell signaling. However, the particular “output” of the Pba Svx action in terms of plant-pathogen interactions and plant immune responses remained unknown. The Svx proteins are largely unexplored in Dickeya species, even though some of them have genes encoding two Svx homologs. Therefore, our study aims to compare the structural and catalytic properties of the Svx proteins of Pba and D. solani (Dso) and to test the phytoimmune properties of these proteins. Two assayed Dso Svx proteins, similar to Pba Svx, were gluzincin metallopeptidases with conservative tertiary structures. The two domains of the Svx proteins form electronegative clefts where the active centers of the peptidase domains are located. All three assayed Svx proteins possessed phytoimmunosuppressory properties and induced ethylene-mediated plant susceptible responses that play a decisive role in Pba-caused disease.

Phytopathogenic microorganisms, being able to cause plant diseases, usually interact with hosts asymptomatically, resulting in the development of latent infections. Knowledge of the mechanisms that trigger a switch from latent to typical, symptomatic infection is of great importance from the perspectives of both fundamental science and disease management. No studies to date have compared, at the systemic molecular level, the physiological portraits of plants when different infection types (typical and latent) are developed. The only phytopathogenic bacterium for which latent infections were not only widely described but also at least fluently characterized at the molecular level is Pectobacterium atrosepticum (Pba). The present study aimed at the comparison of plant transcriptome responses during typical and latent infections caused by Pba in order to identify and then experimentally verify the key molecular players that act as switchers, turning peaceful plant-Pba coexistence into a typical infection. Based on RNA-Seq, we predicted plant cell wall-, secondary metabolism-, and phytohormone-related genes whose products contributed to the development of the disease or provided asymptomatic plant—Pba interactions. By treatment tests, we confirmed that a switch from latent to typical Pba-caused infection is determined by the plant susceptible responses mediated by the joint action of ethylene and jasmonates.

Synchytrium endobioticum , the causal agent of potato wart disease, poses a major threat to commercial potato production. Understanding the roles of transcriptionally regulated genes following pathogen infection is necessary for understanding the system-level host response to pathogen. Although some understanding of defense mechanisms against S. endobioticum infection has been gained for incompatible interactions, the genes and signaling pathways involved in the compatible interaction remain unclear. Based on the collection of wart diseased tubers of a susceptible cultivar, we performed phenotypic and dual RNA-Seq analyses of wart lesions in seven stages of disease progression. We totally detected 5,052 differentially expressed genes (DEGs) by comparing the different stages of infection to uninfected controls. The tendency toward differential gene expression was active rather than suppressed under attack by the pathogen. The number of DEGs step-up along with the development of the disease and the first, third and seventh of the disease stages showed substantially increase of DEGs in comparison of the previous stage. The important functional groups identified via Gene ontology (GO) and KEGG enrichment were those responsible for plant-pathogen interaction, fatty acid elongation and phenylpropanoid biosynthesis. Gene coexpression networks, composed of 17 distinct gene modules that contained between 25 and 813 genes, revealed high interconnectivity of the induced response and led to the identification of a number of hub genes enriched at different stages of infection. These results provide a comprehensive perspective on the global response of potato to S. endobioticum infection and identify a potential transcriptional regulatory network underlying this susceptible response, which contribute to a better understanding of the potato– S. endobioticum pathosystem.

The interaction between ornamental succulents and the root-knot nematode (Meloidogyne spp.) is poorly known. Morpho-anatomical modifications induced by M. incognita to roots of Echeveria cimette and Pachyphytum compactum (Crassulaceae) were analyzed. The affected roots of both taxa showed: numerous galls with egg masses, hyperplastic reactions, cell suberization, disorganized vascular tissues, and development of multinucleated giant cells. Although both hosts were shown to be susceptible, certain characteristics evidenced plant defense reactions. In E. cimette, in those zones of the gall cortex that had great accumulation of tannins no females or egg masses were observed and this compound would be playing a role of a natural defense barrier. Suberized cells surrounding the egg masses could limit the movement of hatched juveniles. In P. compactum, the presence of branched roots with excessive atypical short extensions was noticeable. They were highly suberized and would act as a barrier preventing the loss of water and solutes; they might also be related to a defense mechanism, since they had tannins. Root cell studies of E. cimette and P. compactum parasitized by M. incognita are described for the first time. These results show the importance of commercializing ornamental plants with an adequate sanitary control to avoid the dispersal of this polyphagous nematode. Vegetative propagation of succulents is highlighted, since when they are affected by nematodes, the cuttings can be used as a resource for the conservation of plants.

The transmission of seed-borne pathogens by the germinating seed is responsible for major crop diseases. The immune responses of the seed facing biotic invaders are poorly documented so far. The Arabidopsis thaliana/Alternaria brassicicola patho-system was used to describe at the transcription level the responses of germinating seeds and young seedling stages to infection by the necrotrophic fungus. RNA-seq analyses of healthy versus inoculated seeds at 3 days after sowing (DAS), stage of radicle emergence, and at 6 and 10 DAS, two stages of seedling establishment, identified thousands of differentially expressed genes by Alternaria infection. Response to hypoxia, ethylene and indole pathways were found to be induced by Alternaria in the germinating seeds. However, surprisingly, the defense responses, namely the salicylic acid (SA) pathway, the response to reactive oxygen species (ROS), the endoplasmic reticulum-associated protein degradation (ERAD) and programmed cell death, were found to be strongly induced only during the latter post-germination stages. We propose that this non-canonical immune response in early germinating seeds compared to early seedling establishment was potentially due to the seed-to-seedling transition phase. Phenotypic analyses of about 14 mutants altered in the main defense pathways illustrated these specific defense responses. The unexpected germination deficiency and insensitivity to Alternaria in the glucosinolate deficient mutants allow hypothesis of a trade-off between seed germination, necrosis induction and Alternaria transmission to the seedling. The imbalance of the SA and jasmonic acid (JA) pathways to the detriment of the JA also illustrated a non-canonical immune response at the first stages of the seedling.

Opisthorchis viverrini is a carcinogenic parasite that can cause bile duct cancer called cholangiocarcinoma. A study of the immune response of this parasite in susceptible and non-susceptible hosts may provide a clue to develop vaccines and immunodiagnostic markers, which are currently not available. Here, we compared the antibody response in susceptible Golden Syrian hamsters and non-susceptible BALB/c mice infected by the liver fluke. In mice, the antibody was detected between 1 and 2 weeks post-infection, whereas it was positive between 2 and 4 weeks post-infection in hamsters. Immunolocalization revealed that the antibody from mice reacts strongly with the tegumental surface and gut epithelium of the worm, while hamster antibody showed a weak signal in the tegument and a comparable signal in the gut of the worm. Immunoblot of the tegumental proteins demonstrated that while hamster antibody showed a broad specificity, mice strongly reacted with a single protein band. Mass spectrometry revealed these immunogenic targets. Recombinant proteins of the reactive targets were produced in the bacterial expression system. The immunoblot of these recombinant proteins confirm the reactivity of their native form. In summary, there is a different antibody response against O. viverrini infection in susceptible and non-susceptible hosts. The non-susceptible host reacts quicker and stronger than the susceptible host.

Several studies have investigated soil microbial biodiversity, but understanding of the mechanisms underlying plant responses to soil microbiota remains in its infancy. Here, we focused on tomato (Solanum lycopersicum), testing the hypothesis that plants grown on native soils display different responses to soil microbiotas. Using transcriptomics, proteomics, and biochemistry, we describe the responses of two tomato genotypes (susceptible or resistant to Fusarium oxysporum f. sp. lycopersici) grown on an artificial growth substrate and two native soils (conducive and suppressive to Fusarium). Native soils affected tomato responses by modulating pathways involved in responses to oxidative stress, phenol biosynthesis, lignin deposition, and innate immunity, particularly in the suppressive soil. In tomato plants grown on steam-disinfected soils, total phenols and lignin decreased significantly. The inoculation of a mycorrhizal fungus partly rescued this response locally and systemically. Plants inoculated with the fungal pathogen showed reduced disease symptoms in the resistant genotype in both soils, but the susceptible genotype was partially protected from the pathogen only when grown on the suppressive soil. The ‘state of alert’ detected in tomatoes reveals novel mechanisms operating in plants in native soils and the soil microbiota appears to be one of the drivers of these plant responses.

Major environmental and genetic factors determining stress-related protein abundance are discussed.Major aspects of protein biological function including protein isoforms and PTMs, cellular localization and protein interactions are discussed.Functional diversity of protein isoforms and PTMs is discussed. Abiotic stresses reveal profound impacts on plant proteomes including alterations in protein relative abundance, cellular localization, post-transcriptional and post-translational modifications (PTMs), protein interactions with other protein partners, and, finally, protein biological functions. The main aim of the present review is to discuss the major factors determining stress-related protein accumulation and their final biological functions. A dynamics of stress response including stress acclimation to altered ambient conditions and recovery after the stress treatment is discussed. The results of proteomic studies aimed at a comparison of stress response in plant genotypes differing in stress adaptability reveal constitutively enhanced levels of several stress-related proteins (protective proteins, chaperones, ROS scavenging- and detoxification-related enzymes) in the tolerant genotypes with respect to the susceptible ones. Tolerant genotypes can efficiently adjust energy metabolism to enhanced needs during stress acclimation. Stress tolerance vs. stress susceptibility are relative terms which can reflect different stress-coping strategies depending on the given stress treatment. The role of differential protein isoforms and PTMs with respect to their biological functions in different physiological constraints (cellular compartments and interacting partners) is discussed. The importance of protein functional studies following high-throughput proteome analyses is presented in a broader context of plant biology. In summary, the manuscript tries to provide an overview of the major factors which have to be considered when interpreting data from proteomic studies on stress-treated plants.

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Leptospirosis is a neglected tropical zoonosis caused by pathogenic spirochetes of the genus . Infected reservoir animals, typically mice and rats, are asymptomatic, carry the pathogen in their renal tubules, and shed pathogenic spirochetes in their urine, contaminating the environment. Humans are accidental hosts of pathogenic . Most human infections are mild or asymptomatic. However, 10% of human leptospirosis cases develop into severe forms, including high leptospiremia, multi-organ injuries, and a dramatically increased mortality rate, which can relate to a sepsis-like phenotype. During infection, the triggering of the inflammatory response, especially through the production of cytokines, is essential for the early elimination of pathogens. However, uncontrolled cytokine production can result in a cytokine storm process, followed by a state of immunoparalysis, which can lead to sepsis and associated organ failures. In this review, the involvement of cytokine storm and subsequent immunoparalysis in the development of severe leptospirosis in susceptible hosts will be discussed. The potential contribution of major pro-inflammatory cytokines in the development of tissue lesions and systemic inflammatory response, as well as the role of anti-inflammatory cytokines in contributing to the onset of a deleterious immunosuppressive cascade will also be examined. Data from studies comparing susceptible and resistant mouse models will be included. Lastly, a concise discussion on the use of cytokines for therapeutic purposes or as biomarkers of leptospirosis severity will be provided.