Pathogenesis-related Research Articles

Transcriptional, biochemical, and histochemical response of resistant and susceptible cultivars of Brassica juncea against Albugo candida infection.

White rust disease caused by a biotrophic oomycete Albugo candida is one of the most serious impediments in realizing the production potential of Brassica juncea. Due to the obligate nature of the pathogen, R-gene-based resistance is unstable as the newer virulent races emerge quickly. For this, a deep understanding of the molecular basis of resistance is essential for developing durable resistant varieties. In this study, we selected one susceptible cultivar, 'Pusa Jaikisan' and its single R gene based resistant NIL, 'Pusa Jaikisan WRR as the source of understanding the defense mechanism in B. juncea against A. candida. Comparative histochemical analysis at 12 dpi showed higher callose deposition in the resistant cultivar than in the susceptible which hints towards its possible role in defense mechanism. Based on the biochemical markers observation, total protein was found to have a negative correlation with the resistance. The antioxidant enzymes (POX, CAT, and SOD) and non-enzymatic ROS scavenging compounds such as polyphenols and proline showed a positive correlation with the white rust resistance. Polyphenol Oxidase (PPO) total chlorophyll and total carotenoids were also found to be more abundant in the 'Pusa Jaikisan WRR'. Based on the heat map analysis, PAL was identified to be the comparatively most induced enzyme involved in the defense mechanism. The polyphenol oxidase, total chlorophyll and total carotenoids were also found to show higher activity in the 'Pusa Jaikisan WRR'. Furthermore, to study the defense response of 'Pusa Jaikisan WRR' compared to 'Pusa Jaikisan' against A. candida infection, the gene expression analyses of salicylic acid (SA)-marker PR protein genes (PR1 and PR2) and jasmonic acid (JA)-marker PR protein genes (PR3 and PR12) were done by qRT-PCR. Based on the results, PR2 emerged as the best possible gene for defense against A. candida followed by PR1. PR3 and PR12 also showed positive correlation with the disease resistance which may be due to the JA pathway acting complementary to the SA pathway in case of B. juncea-A. candida interaction. This provides evidence for the JA-SA hormonal crosstalk to be synergistic in case of the white rust resistance.

A critical role of a plant-specific TFIIB-related protein, BRP1, in salicylic acid-mediated immune response.

An integral part of plant immunity is transcription reprogramming by concerted action of specific transcription factors that activate or repress genes through recruitment or release of RNA polymerase II (Pol II). Pol II is assembled into Pol II holoenzyme at the promoters through association with a group of general transcription factors including transcription factor IIB (TFIIB) to activate transcription. Unlike other eukaryotic organisms, plants have a large family of TFIIB-related proteins with 15 members in Arabidopsis including several plant-specific TFIIB-related proteins (BRPs). Molecular genetic analysis has revealed important roles of some BRPs in plant reproductive processes. In this study, we report that Arabidopsis knockout mutants for BRP1, the founding member of the BRP protein family, were normal in growth and development, but were hypersusceptible to the bacterial pathogen Psuedomonas syringae. The enhanced susceptibility of the brp1 mutants was associated with reduced expression of salicylic acid (SA) biosynthetic gene ISOCHORISMATE SYNTHASE 1 (ICS1) and SA-responsive PATHOGENESIS-RELATED (PR) genes. Pathogen-induced SA accumulation was reduced in the brp1 mutants and exogenous SA rescued the brp1 mutants for resistance to the bacterial pathogen. In uninfected plants, BRP1 was primarily associated with the plastids but pathogen infection induced its accumulation in the nucleus. BRP1 acted as a transcription activator in plant cells and binded to the promoter of ICS1. These results collectively indicate that BRP1 is a functionally specialized transcription factor that increasingly accumulates in the nucleus in response to pathogen infection to promote defense gene expression.

Elucidating β-1,3-Glucanase and Peroxidase Physicochemical Properties of Wheat Cell Wall Defense Mechanism against Diuraphis noxia Infestation.

Wheat plants infested by Russian wheat aphids (RWA) induce a cascade of defense responses, including the hypersensitive responses (HR) and induction of pathogenesis-related (PR) proteins, such as β-1,3-glucanase and peroxidase (POD). This study aims to characterize the physicochemical properties of cell wall-associated POD and β-1,3-glucanase and determine their synergism on the cell wall modification during RWASA2-wheat interaction. The susceptible Tugela, moderately resistant Tugela-Dn1, and resistant Tugela-Dn5 cultivars were pregerminated and planted under greenhouse conditions, fertilized 14 days after planting, and irrigated every 3 days. The plants were infested with 20 parthenogenetic individuals of the same RWASA2 clone at the 3-leaf stage, and leaves were harvested at 1 to 14 days post-infestation. The Intercellular wash fluid (IWF) was extracted using vacuum filtration and stored at -20 °C. Leaf residues were crushed into powder and used for cell wall components. POD activity and characterization were determined using 5 mM guaiacol substrate and H2O2, monitoring change in absorbance at 470 nm. β-1,3-glucanase activity, pH, and temperature optimum conditions were demonstrated by measuring the total reducing sugars in the hydrolysate with DNS reagent using β-1,3-glucan and β-1,3-1,4-glucan substrates, measuring the absorbance at 540 nm, and using glucose standard curve. The pH optimum was determined between pH 4 to 9, temperature optimum between 25 and 50 °C, and thermal stability between 30 °C and 70 °C. β-1,3-glucanase substrate specificity was determined at 25 °C and 40 °C using curdlan and barley β-1,3-1,4-glucan substrates. Additionally, the β-1,3-glucanase mode of action was determined using laminaribiose to laminaripentaose. The oligosaccharide hydrolysis product patterns were qualitatively analyzed with thin-layer chromatography (TLC) and quantitatively analyzed with HPLC. The method presented in this study demonstrates a robust approach for infesting wheat with RWA, extracting peroxidase and β-1,3-glucanase from the cell wall region and their comprehensive biochemical characterization.

Proxitome profiling reveals a conserved SGT1-NSL1 signaling module that activates NLR-mediated immunity

Suppressor of G2 allele of skp1 (SGT1) is a highly conserved eukaryotic protein that plays a vital role in growth, development, and immunity in both animals and plants. Although some SGT1 interactors have been identified, the molecular regulatory network of SGT1 remains unclear. SGT1 serves as a co-chaperone to stabilize protein complexes such as the nucleotide-binding leucine-rich repeat (NLR) class of immune receptors, thereby positively regulating plant immunity. SGT1 has also been found to be associated with the SKP1-Cullin-F-box (SCF) E3 ubiquitin ligase complex. However, whether SGT1 targets immune repressors to coordinate plant immune activation remains elusive. In this study, we constructed a toolbox for TurboID- and split-TurboID-based proximity labeling (PL) assays in Nicotiana benthamiana and used the PL toolbox to explore the SGT1 interactome during pre- and post-immune activation. The comprehensive SGT1 interactome network we identified highlights a dynamic shift from proteins associated with plant development to those linked with plant immune responses. We found that SGT1 interacts with Necrotic Spotted Lesion 1 (NSL1), which negatively regulates salicylic acid-mediated defense by interfering with the nucleocytoplasmic trafficking of non-expressor of pathogenesis-related genes 1 (NPR1) during N NLR-mediated response to tobacco mosaic virus. SGT1 promotes the SCF-dependent degradation of NSL1 to facilitate immune activation, while salicylate-induced protein kinase-mediated phosphorylation of SGT1 further potentiates this process. Besides N NLR, NSL1 also functions in several other NLR-mediated immunity. Collectively, our study unveils the regulatory landscape of SGT1 and reveals a novel SGT1-NSL1 signaling module that orchestrates plant innate immunity.

In Silico Structural and Functional Characterization of the Thaumatin‐Like Gene Family in Phaseolus lunatus Reveals the Potential for Microbial and Antiviral Activity

ABSTRACTThaumatin‐like proteins (TLPs) are part of the pathogenesis‐related (PR) proteins that are important in host plant defense. TLPs have multiple defense functions against pathogens (bacteria, viruses, and fungi) and are involved in other biological processes of several living organisms. However, the biological role of TLPs must be elucidated for other species, such as Phaseolus lunatus, popularly known as lima bean. In this study, we propose to investigate the biological activity of TLPs in P. lunatus, which can help develop a detailed functional characterization of the TLP gene in other crop cultures. As a result, a total of 31 PlTPLs genes and 16 highly conserved cysteine residues for each family member were identified in the lima bean genome. Regarding phylogenetic analysis, 128 TLPs from different plant species, including P. lunatus, were used, and the phenetic tree revealed that the TLPs could be divided into six groups. The leading group was Group 4, containing 34 TLPs; the smallest was Group 7, containing only a single TLP. The analysis of antimicrobial and antiviral activity revealed that 27 PlTLPs have antimicrobial activity and 7 PlTLPs have potential antiviral activity. For chromosomal distribution of the PlTLPs, 8 of 11 chromosomes presented at least one PlTLs on one of the chromosomes. Finally, molecular modeling was carried out between two TLPs (PlTLP5 and PlTLP14), which presented antimicrobial and antiviral activity and did not have allergenic activity. The results showed that the two candidates presented ≥90% of their residues in the favorable regions and ∼10% in the permitted regions, demonstrating that the two PlTLPs are considered promising targets for biotechnological applications, especially those related to the genetic improvement of agricultural crops and the development of antimicrobial agents.

Comparative Proteomic Analysis of Floral Buds before and after Opening in Walnut (Juglans regia L.).

The walnut (Juglans regia L.) is a typical and an economically important tree species for nut production with heterodichogamy. The absence of female and male flowering periods seriously affects both the pollination and fruit setting rates of walnuts, thereby affecting the yield and quality. Therefore, studying the characteristics and processes of flower bud differentiation helps in gaining a deeper understanding of the regularity of the mechanism of heterodichogamy in walnuts. In this study, a total of 3540 proteins were detected in walnut and 885 unique differentially expressed proteins (DEPs) were identified using the isobaric tags for the relative and absolute quantitation (iTRAQ)-labeling method. Among all DEPs, 12 common proteins were detected in all four of the obtained contrasts. GO and KEGG analyses of 12 common DEPs showed that their functions are distributed in the cytoplasm metabolic pathways, photosynthesis, glyoxylate and dicarboxylate metabolism, and the biosynthesis of secondary metabolites, which are involved in energy production and conversion, synthesis, and the breakdown of proteomes. In addition, a function analysis was performed, whereby the DEPs were classified as involved in photosynthesis, morphogenesis, metabolism, or the stress response. A total of eight proteins were identified as associated with the morphogenesis of stamen development, such as stamen-specific protein FIL1-like (XP_018830780.1), putative leucine-rich repeat receptor-like serine/threonine-protein kinase At2g24130 (XP_018822513.1), cytochrome P450 704B1-like isoform X2 (XP_018845266.1), ervatamin-B-like (XP_018824181.1), probable glucan endo-1,3-beta-glucosidase A6 (XP_018844051.1), pathogenesis-related protein 5-like (XP_018835774.1), GDSL esterase/lipase At5g22810-like (XP_018833146.1), and fatty acyl-CoA reductase 2 (XP_018848853.1). Our results predict several crucial proteins and deepen the understanding of the biochemical mechanism that regulates the formation of male and female flower buds in walnuts.

Ripening and rot: How ripening processes influence disease susceptibility in fleshy fruits.

Fleshy fruits become more susceptible to pathogen infection when they ripen; for example, changes in cell wall properties related to softening make it easier for pathogens to infect fruits. The need for high-quality fruit has driven extensive research on improving pathogen resistance in important fruit crops such as tomato (Solanum lycopersicum). In this review, we summarize current progress in understanding how changes in fruit properties during ripening affect infection by pathogens. These changes affect physical barriers that limit pathogen entry, such as the fruit epidermis and its cuticle, along with other defenses that limit pathogen growth, such as preformed and induced defense compounds. The plant immune system also protects ripening fruit by recognizing pathogens and initiating defense responses involving reactive oxygen species production, mitogen-activated protein kinase signaling cascades, and jasmonic acid, salicylic acid, ethylene, and abscisic acid signaling. These phytohormones regulate an intricate web of transcription factors (TFs) that activate resistance mechanisms, including the expression of pathogenesis-related genes. In tomato, ripening regulators, such as RIPENING INHIBITOR and NON_RIPENING, not only regulate ripening but also influence fruit defenses against pathogens. Moreover, members of the ETHYLENE RESPONSE FACTOR (ERF) family play pivotal and distinct roles in ripening and defense, with different members being regulated by different phytohormones. We also discuss the interaction of ripening-related and defense-related TFs with the Mediator transcription complex. As the ripening processes in climacteric and non-climacteric fruits share many similarities, these processes have broad applications across fruiting crops. Further research on the individual contributions of ERFs and other TFs will inform efforts to diminish disease susceptibility in ripe fruit, satisfy the growing demand for high-quality fruit and decrease food waste and related economic losses.

Volatiles emitted by Pseudomonas aurantiaca ST-TJ4 trigger systemic plant resistance to Verticillium dahliae

Verticillium dahliae is among the most devastating fungal pathogens, causing significant economic harm to agriculture and forestry. To address this problem, researchers have focused on eliciting systemic resistance in host plants through utilizing volatile organic compounds (VOCs) produced by biological control agents. Herein, we meticulously measured the quantity of V. dahliae pathogens in plants via RTqPCR, as well as the levels of defensive enzymes and pathogenesis-related (PR) proteins within plants. Finally, the efficacy of VOCs in controlling Verticillium wilt in cotton was evaluated. Following treatment with Pseudomonas aurantiaca ST-TJ4, the expression of specific VdEF1-α genes in cotton decreased significantly. The incidence and disease indices also decreased following VOC treatment. In cotton, the salicylic acid (SA) signal was strongly activated 24 h posttreatment; then, hydrogen peroxide (H2O2) levels increased at 48 h, and peroxidase (POD) and catalase (CAT) activities increased to varying degrees at different time points. The malondialdehyde (MDA) content and electrolyte leakage in cotton treated with VOCs were lower than those in the control group, and the expression levels of chitinase (CHI) and PR genes (PR10 and PR17), increased at various time points under the ST-TJ4 treatment. The activity of phenylalanine ammonia lyase (PAL) enzymes in cotton treated with VOCs was approximately 1.26 times greater than that in control plants at 24 h，while the contents of phenols and flavonoids increased significantly in the later stage. Additionally, 2-undecanone and 1-nonanol can induce a response in plants that enhances disease resistance. Collectively, these findings strongly suggest that VOCs from ST-TJ4 act as elicitors of plant defence and are valuable natural products for controlling Verticillium wilt.

Food-Pollen Cross-Reactivity and its Molecular Diagnosis in China.

Plant-derived foods are one of the most common causative sources of food allergy in China, with a significant relationship to pollinosis. This review aims to provide a comprehensive overview of this food-pollen allergy syndrome and its molecular allergen diagnosis to better understand the cross-reactive basis. Food-pollen cross-reactivity has been mainly reported in Northern China, Artemisia pollen is the major related inhalant source, followed by tree pollen (Betula), while grass pollen plays a minor role. Pollen allergy is relatively low in Southern China, with allergies to grass pollen being more important than weed and tree pollens. Rosaceae fruits and legume seeds stand out as major related allergenic foods. Non-specific lipid transfer protein (nsLTP) has been found to be the most clinically relevant cross-reacting allergenic component, able to induce severe reactions. PR-10, profilin, defensin, chitinase, and gibberellin-regulated proteins are other important cross-reactive allergen molecules. Artemisia pollen can induce allergenic cross-reactions with a wide range of plant-derived foods in China, and spring tree pollens (Betula) are also important. nsLTP found in both pollen and plant-derived food is considered the most significant allergen in food pollen cross-reactivity. Component-resolved diagnosis with potential allergenic proteins is recommended to improve diagnostic accuracy and predict the potential risk of causing allergic symptoms.

Genome-wide Characterization of Small Secreted Peptides in Nicotiana tabacum and Functional Assessment of NtLTP25 in Plant Immunity.

Small secreted peptides (SSPs), serving as signaling molecules for intercellular communication, play significant regulatory roles in plant growth, development, pathogen immunity, and responses to abiotic stress. Despite several SSPs, such as PIP, PSK, and PSY having been identified to participate in plant immunity, the majority of SSPs remain understudied, necessitating the exploration and identification of SSPs regulating plant immunity from vast genomic resources. Here we systematically characterized 756 putative SSPs across the genome of Nicotiana tabacum. 173 SSPs were further annotated as established SSPs, such as nsLTP, CAPE, and CEP. Furthermore, we detected the expression of 484 putative SSP genes in five tissues, with 83 SSPs displaying tissue-specific expression. Transcriptomic analysis of tobacco roots under plant defense hormones revealed that 46 SSPs exhibited specific responsiveness to salicylic acid (SA), and such response was antagonistically regulated by methyl jasmonate. It's worth noting that among these 46 SSPs, 16 members belong to nsLTP family, and one of them, NtLTP25, was discovered to enhance tobacco's resistance against Phytophthora nicotianae. Overexpression of NtLTP25 in tobacco enhanced the expression of ICS1, subsequently stimulating the biosynthesis of SA and the expression of NPR1 and pathogenesis-related genes. Concurrently, NtLTP25 overexpression activated genes associated with ROS scavenging, consequently mitigating the accumulation of ROS during the subsequent phases of pathogenesis. These discoveries indicate that these 46 SSPs, especially the 16 nsLTPs, might have a vital role in governing plant immunity that relies on SA signaling. This offers a valuable source for pinpointing SSPs involved in regulating plant immunity.

Genome-wide characterization and expression analysis of the cultivated peanut AhPR10 gene family mediating resistance to Aspergillusflavus L.

The pathogenesis-related protein PR10 is essential for plant growth, development, and stress responses. In this study, PR10 genes in cultivated peanut (Arachis hypogaea L.) were systematically identified, after which their phylogenetic relationships, conserved motifs, gene structures, and syntenic relationships were analyzed. A total of 54 AhPR10 genes were identified. They were then divided into eight groups according to their phylogenetic relationships, which were supported by the characterization of gene structures and conserved motifs. Analyses of chromosomal distribution and synteny revealed that segmental duplications were critical for the expansion of the AhPR10 gene family. In addition, the identified AhPR10 genes had constitutive and inducible expression patterns. Notably, AhPR10-7, AhPR10-33, and AhPR10-41 may have crucial functions affecting the resistance of peanut to A. flavus. In vitro fungistatic experiments indicated that recombinant AhPR10-33 can effectively inhibit A. flavus mycelial growth. The study results provide useful insights for future research on AhPR10 functions that protect peanut from the detrimental effects of A. flavus.

Genome-wide analysis of the family 10 plant pathogenesis-related proteins in Pyrus bretschneideri and functional analysis of PbrMLP for Colletotrichum fructicola resistance

Pathogenesis-related (PR) genes are key regulators of plant adaptation responses to biotic and abiotic stresses. Family 10 PRs (PR10s, also known as major latex proteins) are usually induced by pathogens and environmental stresses. However, the evolutionary trajectory and functional divergence of the PR10 gene family in Chinese white pear (Pyrus bretschneideri ‘Dangshan Suli’) remain uncharacterized. The presence of 61 PR10s was detected across six Rosaceae species. The PR10 gene family was classified into two distinct groups by employing phylogenetic analysis and the taxonomic criteria of model plants. Interspecies synchrony revealed an ancient origin of the PR10 family in the six Rosaceae species, with 18 synchronic gene pairs. The expansion and evolution of the PR10 family were driven by various types of gene duplication events, with whole-genome duplication (WGD) being the primary mechanism. A candidate Colletotrichum fructicola (C. fructicola) resistance gene Pyrusbretschneiderimajor latex-like proteins (PbrMLP) belonging to the PR10 family was screened through transcriptomics and qRT-PCR. In addition, PbrMLP-silenced pear seedlings were more sensitive to C. fructicola than the controls. These results showed that PbrMLP is a candidate gene vital for anthracnose resistance in pears. These findings offer novel insights into the molecular mechanisms underlying the resistance to pear anthracnose infection in Rosaceae species and identify potential target genes for developing disease-resistant cultivars through genetic engineering.

Comparative expression profile of selected genes in Venturia inaequalis Cooke (Wint.) infecting apple fruits and leaves

Scab is a noxious fungal disease of apples (Malus domestica Borkh) in all apple producing regions caused by a host-specific phytopathogen Venturia inaequalis Cooke (Wint.). Its symptoms include black or brown lesions on leaves as well as on fruits, and causes fruit deformation. In this study, V. inaequalis was isolated from infected fruit samples and expression level of selected pathogenesis related genes in scab infected fruits and leaves was studied. The isolated fungus formed a brown coloured mat-like colony having septate mycelium and produced acute ovoid shaped conidia. Molecular characterization of the fungus was done by amplification and sequencing of internal transcribed spacer (ITS) and Cytochrome (CYP51A1) regions of the isolate. The Sanger sequencing of amplicons and sequence analysis using BLAST tool of the NCBI against GenBank database confirmed that the obtained sequence of ITS and CYP51A1 regions had 99.6 % and 98 % sequence identity with the reference V. inaequalis, respectively. The isolated strain of V. inaequalis was submitted in the fungal repository of Microbial Type Culture Collection (MTCC), India. The phylogenetic analysis of ITS region of the isolate revealed that the isolated strain of V. inaequalis was more closely related to Fusicladium eriobotryae compared to other Venturia species. The expression levels of pathogenesis related genes viz. CIN1, CE5 and VICE16 were higher in infected leaves as compared to infected fruits. Whereas expression of VICE12 and GH28 were higher in infected fruits compared to infected leaves. VICE4 gene showed equal level of expression during infection in both fruits and leaves, which was also maximum as compared to the control treatment. The transcript analysis of aforementioned genes of V. inaequalis gives the insights of the pathogen's expression profile during pathogenesis in fruits and leaves. This expression analysis can form a basis selecting pathogenesis related genes as targets for developing dsRNA expressing constructs with an aim to reduce RNAi mediated silencing of specific genes, in a futuristic biotechnological based solution to deal with apple scab disease.

Experience of allergen-specific immunotherapy in the patient with oral and systemic manifestations of birch pollen allergy

Introduction. Allergy to birch pollen is a common allergic disease. The main allergen of birch pollen is Bet v 1. The Bet v 1 protein structure is the similar to proteins of hazel, alder and elm pollen, as well as fruits proteins (apples, apricots, peaches, cherries) and vegetables ones (carrots, celery). Therefore, children with an allergy to the Bet v 1 protein may experience oral allergy syndrome (OAS) and even anaphylaxis when eating these foods. Allergen-specific immunotherapy (ASIT) is the indication for the pollen allergy treatment.Presentation of the clinical case. A 11 years old child was observed with a diagnosis of bronchial asthma, allergic form, moderate persistent clinical course. Pollinosis. Allergic rhinitis. Allergic conjunctivitis. Allergy to birch pollen (Bet v 1). Cross food hypersensitivity: oral syndrome (PR-10 proteins) and anaphylaxis (hazelnuts, peanuts). Systemic manifestations of pollen allergy limit immunotherapy due to the possible development of adverse reactions.The child was prescribed sublingual immunotherapy (SLIT) with the medication “Staloral birch pollen allergen”. Baseline therapy was chosen for the child to achieve control of asthma and rhinitis, a hypoallergenic diet with the exclusion of significant food allergens was prescribed. Asthma and rhinitis exacerbation and OAS was observed during the 1st and 2nd treatment courses. Against the background of baseline therapy, SLIT was continued. The full maintenance dose was achieved during the 3rd SLIT course. Immunotherapy contributed to the reduction of symptoms of rhinitis and asthma, reduction of disease clinical course severity, reduction of baseline medications doses and OAS relief.

Local manifestations of cross food allergy in children with clinical symptoms of respiratory allergy to birch pollen: solutions

Introduction. According to modern data, Oral Allergy Syndrome (OAS) is most often formed by patients sensitized to the birch family: up to 73% of patients allergic to birch experienced OAS. 86% of them experience their oral symptoms year-round, which significantly affects the quality of life of these patients. The effectiveness of AIT in the treatment of respiratory allergy symptoms is beyond doubt, while the effect on the manifestations of cross-food allergies requires additional study.Objective. To study the clinical effectiveness of the formation of oral tolerance to fruits and vegetables under the influence of allergen-specific immunotherapy (ASIT) with the allergen Staloral® “Birch pollen allergen” (Stallergenes Greer, France).Material and methods. The study (prospective open comparative longitudinal) included 184 patients with respiratory allergy to birch pollen aged 5 to 16 years with confirmed sensitization to the major molecule (Bet v 1). Children of the main group (n = 134, 7.0 [5.0; 9.0] years) had OAS. Children from the comparison group (n = 50, 7.0 [6.0; 10.0] years) did not have OAS. A clinical examination, general clinical and allergological examinations were carried out for each child. Component allergy diagnostics was performed using a multiplex panel (ISAC-112, ImmunoCAP) for children with OAS (n = 40) who had multiple manifestations of cross-food allergies. Patients of both groups (n = 184) received a three-year course of AIT with the allergen Staloral® “Birch pollen allergen”.Results. In patients with OAS, it was possible to achieve the formation of oral tolerance (total or partial) to fresh vegetables and fruits in 88.81% (n = 119, p = 0.000). There was a decrease in the intensity and duration of respiratory allergy symptoms during the pollination season, and the need for pharmacotherapy after a three-year course of AIT Staloral® “Birch pollen allergen” in children of both groups.Conclusions: three-year AIT with the allergen Staloral® “Birch pollen allergen” is able to form oral tolerance in children with cross food allergies to PR-10 proteins of vegetables and fruits.

Pathogenicity and induced resistance in Larix kaempferi and Larix olgensis inoculated with Endoconidiophora fujiensis.

With climate warming and economic globalization, insect-microbe assemblages are becoming increasingly responsible for various devastating forest diseases worldwide. Japanese larch (Larix kaempferi) is extensively cultivated in China because of its high survival rate, rapid maturation and robust mechanical properties. Endoconidiophora fujiensis, an ophiostomatoid fungus associated with Ips subelongatus, has been identified as a lethal pathogen of L. kaempferi in Japan. However, there is a dearth of research on the pathogenicity of E. fujiensis in larches in China. Therefore, we investigated the pathogenicity of E. fujiensis in introduced L. kaempferi and indigenous larch (Larix olgensis) trees and compared the induced resistance responses to the pathogen in both tree species in terms of physiology and gene expression. Five-year-old saplings and 25-year-old adult trees of L. olgensis and L. kaempferi were inoculated in parallel during the same growing season. Endoconidiophora fujiensis exhibited high pathogenicity in both larch species, but particularly in L. kaempferi compared with L. olgensis adult trees; adult L. olgensis was more resistant to E. fujiensis than adult L. kaempferi, which was reflected in higher accumulation of defensive monoterpenes, such as myrcene, 3-carene and limonene and the earlier induction of defense genes catalase (CAT) and pathogenesis-related protein 1 (PR1). This study contributes to our understanding of the interactions between bark beetle-associated ophiostomatoid fungi and host larches, from phenotypic responses to alterations in secondary metabolites via defense- and metabolism-related gene activation, providing a valuable foundation for the management of larch diseases and pests in the future.

Fine-Tuning of Arabidopsis thaliana Response to Endophytic Colonization by Gluconacetobacter diazotrophicus PAL5 Revealed by Transcriptomic Analysis.

Gluconacetobacter diazotrophicus is a diazotrophic endophytic bacterium that promotes the growth and development of several plant species. However, the molecular mechanisms activated during plant response to this bacterium remain unclear. Here, we used the RNA-seq approach to understand better the effect of G. diazotrophicus PAL5 on the transcriptome of shoot and root tissues of Arabidopsis thaliana. G. diazotrophicus colonized A. thaliana roots and promoted growth, increasing leaf area and biomass. The transcriptomic analysis revealed several differentially expressed genes (DEGs) between inoculated and non-inoculated plants in the shoot and root tissues. A higher number of DEGs were up-regulated in roots compared to shoots. Genes up-regulated in both shoot and root tissues were associated with nitrogen metabolism, production of glucosinolates and flavonoids, receptor kinases, and transcription factors. In contrast, the main groups of down-regulated genes were associated with pathogenesis-related proteins and heat-shock proteins in both shoot and root tissues. Genes encoding enzymes involved in cell wall biogenesis and modification were down-regulated in shoots and up-regulated in roots. In contrast, genes associated with ROS detoxification were up-regulated in shoots and down-regulated in roots. These results highlight the fine-tuning of the transcriptional regulation of A. thaliana in response to colonization by G. diazotrophicus PAL5.

Extraction optimization, physicochemical properties, and inhibitory effect against tobacco mosaic virus of the protein from discarded tobacco leaves

Plant proteins have been attracting increasing attention due to their significant antiviral activity against tobacco mosaic virus (TMV). This paper aimed to investigate the tobacco endogenous protein and the anti-TMV effects. Firstly, the extraction of protein from discarded tobacco leaves (DTLP) was optimized by response surface methodology (RSM). The maximum DTLP yield reached to 8.32 % under the condition of solid-liquid ratio 1:19, temperature 60 °C and pH 12. DTLP was rich in hydrophilic amino acids, such as aspartic acid (8.08 ± 0.34 g/100 g) and glutamic acid (8.02 ± 0.42 g/100 g). DTLP structure was compact and stable with a denaturation temperature of 99.7 °C. Furthermore, the anti-TMV experiments revealed that DTLP showed inactive and protective activities against TMV with inhibitory rates (79.2 % and 75.4 %, respectively) at 500 µg/mL, and inhibited the polymerization of TMV-CP to damage TMV particles. In addition, DTLP increased the expressions of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and phenylalanine ammonia lyase (PAL) in tobacco leaves by 1.55, 1.18, 9.13 and 2.92 times, respectively. Transcriptomics further verified that DTLP increased the expressions of TGA, WRKY, and PR1 genes for up-regulating the salicylic acid (SA) and pathogenesis-related proteins (PRs), thereby improving the system resistance of tobacco plants. Therefore, DTLP could be potentially developed as an alternative drug to treat plant viral diseases due to its broad-spectrum anti-TMV activity.

Transfection of entomopathogenic Metarhizium species with a mycovirus confers hypervirulence against two lepidopteran pests

Although most known viruses infecting fungi pathogenic to higher eukaryotes are asymptomatic or reduce the virulence of their host fungi, those that confer hypervirulence to entomopathogenic fungus still need to be explored. Here, we identified and studied a novel mycovirus in Metarhizium flavoviride, isolated from small brown planthopper (Laodelphax striatellus). Based on molecular analysis, we tentatively designated the mycovirus as Metarhizium flavoviride partitivirus 1 (MfPV1), a species in genus Gammapartitivirus, family Partitiviridae. MfPV1 has two double-stranded RNAs as its genome, 1,775 and 1,575 bp in size respectively, encapsidated in isometric particles. When we transfected commercial strains of Metarhizium anisopliae and Metarhizium pingshaense with MfPV1, conidiation was significantly enhanced (t test; P-value < 0. 01), and the significantly higher mortality rates of the larvae of diamondback moth (Plutella xylostella) and fall armyworm (Spodoptera frugiperda), two important lepidopteran pests were found in virus-transfected strains (ANOVA; P-value < 0.05). Transcriptomic analysis showed that transcript levels of pathogenesis-related genes in MfPV1-infected M. anisopliae were obviously altered, suggesting increased production of metarhizium adhesin-like protein, hydrolyzed protein, and destruxin synthetase. Further studies are required to elucidate the mechanism whereby MfPV1 enhances the expression of pathogenesis-related genes and virulence of Metarhizium to lepidopteran pests. This study presents experimental evidence that the transfection of other entomopathogenic fungal species with a mycovirus can confer significant hypervirulence and provides a good example that mycoviruses could be used as a synergistic agent to enhance the biocontrol activity of entomopathogenic fungi.

Analysis of chitinase gene family in barley and function study of HvChi22 involved in drought tolerance.

Chitinase (Chi) is a pathogenesis-related protein, also reported to play an important role in plant responses to abiotic stress. However, its role in response to abiotic stress in barley is still unclear. In this study, a total of 61 Chi gene family members were identified from the whole genome of wild barley EC_S1. Phylogenetic analysis suggested that these family genes were divided into five groups. Among these genes, four pairs of collinearity genes were discovered. Besides, abundant cis-regulatory elements, including drought response element and abscisic acid response element were identified in the promoter regions of HvChi gene family members. The expression profiles revealed that most HvChi family members were significantly up-regulated under drought stress, which was also validated by RT-qPCR measurements. To further explore the role of Chi under drought stress, HvChi22 was overexpressed in Arabidopsis. Compared to wild-type plants, overexpression of HvChi22 enhanced drought tolerance by increasing the activity of oxidative protective enzymes, which caused less MDA accumulation. Our study improved the understanding of the Chi gene family under drought stress in barley, and provided a theoretical basis for crop improvement strategies to address the challenges posed by changing environmental conditions.