A novel method for extraction of high purity and high production Phytophthora sojae oospores.

BACKGROUND: Phytophthora sojae, a soil-borne oomycete pathogen, has been a yield limiting factor for more than 60 years on soybean. The resurgence of P. sojae (Phytophthora sojae) is primarily ascribed to the durable oospores found in soil and remnants of the disease. P. sojae is capable of infesting at any growth periods of the soybean, and the succeed infestation of P. sojae is predominantly attributed to long-lived oospores present in soil. Comprehending the molecular mechanisms that drive oospores formation and their significance in infestation is the key for effective management of the disease. However, the existing challenges in isolating and extracting significant quantities of oospores pose limitations in investigating the sexual reproductive stages of P. sojae. RESULTS: The study focused on optimizing and refining the culture conditions and extraction process of P. sojae, resulting in establishment of an efficient and the dependable method for extraction. Novel optimized approach was yielded greater quantities of high-purity P. sojae oospores than traditional methods. The novel approach exceeds the traditional approaches with respect to viability, survival ability, germination rates of new oospores and the pathogenicity of oospores in potting experiments. CONCLUSION: The proposed method for extracting P. sojae oospores efficiently yielded a substantial quantity of highly pure, viable, and pathogenic oospores. The enhancements in oospores extraction techniques will promote the research on the sexual reproductive mechanisms of P. sojae and lead to the creation of innovative and effective approaches for managing oomycete diseases.

Recognition of the inducible, secretory small protein OsSSP1 by the membrane receptor OsSSR1 and the co-receptor OsBAK1 confers rice resistance to the blast fungus.

The plant apoplast, which serves as the frontline battleground for long-term host-pathogen interactions, harbors a wealth of disease resistance resources. However, the identification of the disease resistance proteins in the apoplast is relatively lacking. In this study, we identified and characterized the rice secretory protein OsSSP1 (Oryza sativa secretory small protein 1). OsSSP1 can be secreted into the plant apoplast, and either in vitro treatment of recombinant OsSSP1 or overexpression of OsSSP1 in rice could trigger plant immune response. The expression of OsSSP1 is suppressed significantly during Magnaporthe oryzae infection in the susceptible rice variety Taibei 309, and OsSSP1-overexpressing lines all show strong resistance to M. oryzae. Combining the knockout and overexpression results, we found that OsSSP1 positively regulates plant immunity in response to fungal infection. Moreover, the recognition and immune response triggered by OsSSP1 depend on an uncharacterized transmembrane OsSSR1 (secretory small protein receptor 1) and the key co-receptor OsBAK1, since most of the induced immune response and resistance are lost in the absence of OsSSR1 or OsBAK1. Intriguingly, the OsSSP1 protein is relatively stable and can still induce plant resistance after 1 week of storage in the open environment, and exogenous OsSSP1 treatment for a 2-week period did not affect rice yield. Collectively, our study reveals that OsSSP1 can be secreted into the apoplast and percepted by OsSSR1 and OsBAK1 during fungal infection, thereby triggering the immune response to enhance plant resistance to M. oryzae. These findings provide novel resources and potential strategies for crop breeding and disease control.

Plant Biostimulant as an Environmentally Friendly Alternative to Modern Agriculture.

Ensuring the safety of crop production presents a significant challenge to humanity. Pesticides and fertilizers are commonly used to eliminate external interference and provide nutrients, enabling crops to sustain growth and defense. However, the addition of chemical substances does not meet the environmental standards required for agricultural production. Recently, natural sources such as biostimulants have been found to help plants with growth and defense. The development of biostimulants provides new solutions for agricultural product safety and has become a widely utilized tool in agricultural. The review summarizes the classification of biostimulants, including humic-based biostimulant, protein-based biostimulant, oligosaccharide-based biostimulant, metabolites-based biostimulants, inorganic substance, and microbial inoculant. This review attempts to summarize suitable alternative technology that can address the problems and analyze the current state of biostimulants, summarizes the research mechanisms, and anticipates future technological developments and market trends, which provides comprehensive information for researchers to develop biostimulants.

The MYB transcription factor OsMYBxoc1 regulates resistance to Xoc by directly repressing transcription of the iron transport gene OsNRAMP5 in rice.

Bacterial leaf streak caused by Xanthomonas oryzae pv. oryzicola (Xoc) is a continuous threat to rice cultivation, leading to substantial yield losses with socioeconomic implications. Iron ions are essential mineral nutrients for plant growth, but little information is available on how they influence mechanisms of rice immunity against Xoc. Here, we investigated the role of the myeloblastosis-related (MYB) transcriptional repressor OsMYBxoc1 in modulation of rice resistance through control of iron ion transport. Overexpression of OsMYBxoc1 significantly increased rice resistance, whereas OsMYBxoc1 RNA-interference lines and knockout mutants showed the opposite result. Suppression of OsMYBxoc1 expression dampened the immune response induced by pathogen-associated molecular patterns. We demonstrated that OsMYBxoc1 binds specifically to the OsNRAMP5 promoter and represses transcription of OsNRAMP5. OsNRAMP5, a negative regulator of rice resistance to bacterial leaf streak, possesses metal ion transport activity, and inhibition of OsMYBxoc1 expression increased the iron ion content in rice. Activity of the ion-dependent H2O2 scavenging enzyme catalase was increased in plants with suppressed expression of OsMYBxoc1 or overexpression of OsNRAMP5. We found that iron ions promoted Xoc infection and interfered with the production of reactive oxygen species induced by Xoc. The type III effector XopAK directly inhibited OsMYBxoc1 transcription, indicating that the pathogen may promote its own proliferation by relieving restriction of iron ion transport in plants. In addition, iron complemented the pathogenicity defects of the RS105_ΔXopAK mutant strain, further confirming that iron utilization by Xoc may be dependent upon XopAK. In conclusion, our study reveals a novel mechanism by which OsMYBxoc1 modulates rice resistance by regulating iron accumulation and demonstrates that Xoc can accumulate iron ions by secreting the effector XopAK to promote its own infection.

Common carotid artery diameter and the risk of cardiovascular disease mortality: a prospective cohort study in northeast China.

BACKGROUND: The association between the common carotid artery (CCA) diameter and cardiovascular disease (CVD) is recognized, but the precise nature of this link remains elusive. This study aimed to investigate the potential relationship between CCA diameter and the risk of CVD mortality in a large population in northeast China. METHODS: The current study included 5668 participants (mean age 58.9 ± 10.1 years) from a population-based study conducted in rural areas of northeast China between September 2017 and May 2018. Information on death was collected from baseline until July 31, 2022. The CCA inter-adventitial diameter was measured using ultrasound. Cox proportional-hazard models were employed to explore the relationship between the common carotid artery diameter and cardiovascular mortality. RESULTS: At baseline, the mean CCA diameter (mm) of subjects was 7.30 ± 0.99 and increased significantly with age, ranging from 6.65 ± 0.71 among people 40-49 years to 7.99 ± 1.04 among people ≥ 80 years. CCA diameter was significantly larger in males compared to females (7.51 ± 1.03 versus vs. 7.16 ± 0.94; P < 0.001). A total of 185 participants died of CVD during a median follow-up of 4.48 years. CCA diameters were divided into quartiles, and the highest quartile of carotid diameter (≥ 8.06 mm) had a 2.29 (95% confidence interval [CI]: 1.24, 4.22) times higher risk of CVD mortality than the lowest quartile (≤ 6.65 mm) (P < 0.01) in the fully adjusted model. Each increase in the diameter of the common carotid artery (per SD) raised the risk of cardiovascular death by 36% (hazard ratio [HR]: 1.36; 95% CI: 1.18, 1.57). The subgroup analysis results demonstrated that a per SD increase was associated with a 42% increased risk of CVD mortality in participants aged ≥ 64 years in the fully adjusted model (HR: 1.42; 95%CI: 1.21, 1.66). CONCLUSIONS: Our study indicates the possible incremental value of CCA diameter in optimizing the risk stratification of cardiovascular disease and provides essential insights into reducing the burden of cardiovascular disease.

Autophagy and cell wall integrity pathways coordinately regulate the development and pathogenicity through MoAtg4 phosphorylation in Magnaporthe oryzae.

Autophagy and Cell wall integrity (CWI) signaling are critical stress-responsive processes during fungal infection of host plants. In the rice blast fungus Magnaporthe oryzae, autophagy-related (ATG) proteins phosphorylate CWI kinases to regulate virulence; however, how autophagy interplays with CWI signaling to coordinate such regulation remains unknown. Here, we have identified the phosphorylation of ATG protein MoAtg4 as an important process in the coordination between autophagy and CWI in M. oryzae. The ATG kinase MoAtg1 phosphorylates MoAtg4 to inhibit the deconjugation and recycling of the key ATG protein MoAtg8. At the same time, MoMkk1, a core kinase of CWI, also phosphorylates MoAtg4 to attenuate the C-terminal cleavage of MoAtg8. Significantly, these two phosphorylation events maintain proper autophagy levels to coordinate the development and pathogenicity of the rice blast fungus.

NIT24 and NIT29-mediated IAA synthesis of Xanthomonas oryzae pv. oryzicola suppresses immunity and boosts growth in rice.

Auxin plays a pivotal role in the co-evolution of plants and microorganisms. Xanthomonas oryzae pv. oryzicola (Xoc) stands as a significant factor that affects rice yield and quality. However, the current understanding of Xoc's capability for indole 3-acetic acid (IAA) synthesis and its mechanistic implications remains elusive. In this study, we performed a comprehensive genomic analysis of Xoc strain RS105, leading to the identification of two nitrilase enzyme family (NIT) genes, designated as AKO15524.1 and AKO15829.1, subsequently named NIT24 and NIT29, respectively. Our investigation unveiled that the deletion of NIT24 and NIT29 resulted in a notable reduction in IAA synthesis capacity within RS105, thereby impacting extracellular polysaccharide production. This deficiency was partially ameliorated through exogenous IAA supplementation. The study further substantiated that NIT24 and NIT29 have nitrilase activity and the ability to catalyse IAA production in vitro. The lesion length and bacterial population statistics experiments confirmed that NIT24 and NIT29 positively regulated the pathogenicity of RS105, suggesting that NIT24 and NIT29 may regulate Xoc invasion by affecting IAA synthesis. Furthermore, our analysis corroborated mutant strains, RS105_ΔNIT24 and RS105_ΔNIT29, which elicited the outbreak of reactive oxygen species, the deposition of callose and the upregulation of defence-related gene expression in rice. IAA exerted a significant dampening effect on the immune responses incited by these mutant strains in rice. In addition, the absence of NIT24 and NIT29 affected the growth-promoting effect of Xoc on rice. This implies that Xoc may promote rice growth by secreting IAA, thus providing a more suitable microenvironment for its own colonization. In summary, our study provides compelling evidence for the existence of a nitrilase-dependent IAA biosynthesis pathway in Xoc. IAA synthesis-related genes promote Xoc colonization by inhibiting rice immune defence response and affecting rice growth by increasing IAA content in Xoc.

IL-35 Stabilizes Treg Phenotype to Protect Cardiac Allografts in Mice.

BACKGROUND: Interleukin-35 (IL-35), secreted by regulatory T cells (Treg) and B cells, is immunosuppressive under both physiological and pathological conditions. However, the role of IL-35 in all responses has yet to be investigated. Here, we demonstrate that IL-35 protects allografts by stabilizing the Treg phenotype and suppressing CD8 + T-cell activation in a mouse heart transplantation model. METHODS: The effect of IL-35 on immune cell infiltration in grafts and secondary lymphoid organs was examined using mass cytometry, flow cytometry, and immunofluorescence. Moreover, using quantitative real-time polymerase chain reaction, flow cytometry, and phospho-flow assays, we demonstrated that IL-35 maintains Treg phenotypes to restrain CD8 + T cells via the gp130/signal transducer and activator of transcription 1 pathway. RESULTS: Mass cytometry analysis of intragraft immune cells showed that IL-35 decreased CD8 + T-cell infiltration and increased Foxp3 and IL-35 expressions in Treg. In vitro, we demonstrated that IL-35 directly promoted Treg phenotypic and functional stability and its IL-35 secretion, generating a positive feedback loop. However, Treg are required for IL-35 to exert its suppressive effect on CD8 + T cells in vitro. After depleting Treg in the recipient, IL-35 did not prolong graft survival or decrease CD8 + T-cell infiltration. Mechanistically, we found that IL-35 sustained Treg stability via the gp130/signal transducer and activator of transcription 1 signaling pathway. CONCLUSIONS: Our findings highlight that IL-35 stabilizes the Treg phenotype to ameliorate CD8 + T-cell infiltration in the allograft, which has never been described in the transplanted immunological milieu.

Plant immune inducer ZNC promotes rutin accumulation and enhances resistance to Botrytis cinerea in tomato.

Gray mold is a destructive disease caused by Botrytis cinerea, a pervasive plant pathogen, which poses a threat to both tomato growth and postharvest storage. The utilization of induced resistance presents a potential strategy for combating plant pathogenic attacks. ZNC (zhinengcong), an extract derived from the endophytic fungus Paecilomyces variotii, has been discovered to play a vital role in preventing diverse forms of bacterial infections. Nevertheless, the precise mechanism behind its ability to enhance tomato resistance to fungi remains unclear. In this study, we found that the exogenous spraying of ZNC could significantly improve the resistance of tomato plants to B. cinerea. The results of both the metabolomic analysis and high-performance liquid chromatography (HPLC) demonstrated that tomato plants responded to ZNC treatment by accumulating high levels of rutin. Additional transcriptome analysis uncovered that rutin enhances tomato resistance possible by initiating the generation of reactive oxygen species (ROS) and phosphorylation of mitogen-activated protein kinases (MPKs) related genes expression during the initial phase of invasion by B. cinerea. In addition, we also found that rutin might activate plant immunity by eliciting ethylene (ET) and jasmonic acid (JA)-mediated pathways. Therefore, plant immune inducer ZNC and rutin has bright application prospects and high utilization value to control gray mold.

Application and prospect of metabolomics-related technologies in food inspection.

BACKGROUND: Food inspection covers a broad range of topics, including nutrient analysis, food pollutants, food auxiliary materials, additives, and food sensory identification. The foundation of diverse subjects like food science, nutrition, health research, and the food industry, as well as the desired reference for drafting trade and food legislation, makes food inspection highly significant. Because of their high efficiency, sensitivity, and accuracy, instrumental analysis methods have gradually replaced conventional analytical methods as the primary means of food hygiene inspection. SCOPE AND APPROACH: Metabolomics-based analysis technology, such as nuclear magnetic resonance (NMR), gas chromatography-mass spectrometry (GC-MS), liquid chromatography-mass spectrometry (LC-MS), and capillary electrophoresis-mass spectrometry (CE-MS), has become a widely used analytics platform. This research provides a bird's eye view of the application and future of metabolomics-related technologies in food inspection. KEY FINDINGS AND CONCLUSIONS: We have provided a summary of the features and the application range of various metabolomics techniques, the strengths and weaknesses of different metabolomics platforms, and their implementation in specific inspection procedures. These procedures encompass the identification of endogenous metabolites, the detection of exogenous toxins and food additives, analysis of metabolite alterations during processing and storage, as well as the recognition of food adulteration. Despite the widespread utilization and significant contributions of metabolomics-based food inspection technologies, numerous challenges persist as the food industry advances and technology continues to improve. Thus, we anticipate addressing these potential issues in the future.

Identification of key genes in HER2-positive breast cancer with brain metastasis via bioinformatics methods.

Background: Brain metastasis (BM) represents one of the most common advanced disease states in breast cancer (BC), especially in human epidermal growth factor receptor 2 (HER2)-positive BC, and is associated with poor survival outcomes. Methods: In this study, in-depth analysis of the microarray data from the GSE43837 dataset with 19 BM samples of HER2-positive BC patients and 19 HER2-positive nonmetastatic primary BC samples was conducted. The differentially expressed genes (DEGs) between BM and primary BC samples were identified and function enrichment analysis of the DEGs was conducted to identify potential biological functions. The hub genes were identified by constructing the protein-protein interaction (PPI) network using STRING and Cytoscape. UALCAN and Kaplan-Meier plotter online tools were used to verify the clinical roles of the hub DEGs in HER2-positive BC with BM (BCBM). Results: A total of 1,056 DEGs including 767 downregulated and 289 upregulated genes were identified by comparing the microarray data of the HER2-positive BM and primary BC samples. Functional enrichment analysis demonstrated that the DEGs were mainly enriched in pathways related to extracellular matrix (ECM) organization, cell adhesion, and collagen fibril organization. PPI network analysis identified 14 hub genes. Among these, CD44, COL1A2, MMP14, POSTN, and SOX9 were associated with the survival outcomes of HER2-positive patients. Conclusions: In summary, 5 BM-specific hub genes were identified in the study; those are potential prognostic biomarkers and therapeutic targets for HER2-positive BCBM patients. However, further investigations are necessary to unravel the mechanisms by which these 5 hub genes regulate BM in HER2-positive BC.

SlMYB1 regulates the accumulation of lycopene, fruit shape, and resistance to Botrytis cinerea in tomato.

Fruit lycopene, shape, and resistance are essential traits in vegetables whose final product is fruit, and they are also closely related to and strictly regulated by multiple transcription factors. Lycopene, which cannot be synthesized by the human body and can only be ingested from the outside, was important in maintaining human health. During fruit ripening and post-harvest, tomato plants face a variety of biotic or abiotic stresses, which might inflict great damage to fruit quality due to its flat shape and pointed tip during storage and transportation. Therefore, there is an urgent need for key molecular switches to simultaneously improve fruit lycopene and resistance to biotic stress during ripening. Here, we identified the MYB transcription factor SlMYB1 in tomato plants which could bind to the promoters of lycopene synthesis-related genes, SlLCY1, SlPSY2, and the pathogen-related gene SlPR5 directly, to regulate the fruit lycopene and resistance to Botrytis cinerea in tomato. In addition to regulating lycopene synthesis, SlMYB1 also regulates the content of soluble sugar, soluble protein and flavonoid in tomato. What's more, SlMYB1 could regulate the tomato fruit shape, making it smoother or flatter to prevent skin damage caused by vibration on fruits. RNA sequencing (RNA-seq) further showed that SlMYB1 fruit-specific expression lines had multiple differentially expressed genes compared with those from wild-type plants, suggesting that SlMYB1 might have multiple roles in fruit nutritional quality control and resistance to stresses, which is a rare occurrence in previous studies. In summary, our results revealed that SlMYB1 was an essential multi-functional transcription factor that could regulate the lycopene and resistance to Botrytis cinerea, and change the shape of fruit in tomato plants.

Glutathione and neodiosmin feedback sustain plant immunity.

Plants have evolved a two-layer immune system comprising pattern-triggered immunity (PTI) and effector-triggered immunity (ETI) that is activated in response to pathogen invasion. Microbial patterns and pathogen effectors can be recognized by surface-localized pattern-recognition receptors (PRRs) and intracellularly localized nucleotide-binding leucine-rich repeat receptors (NLRs) to trigger PTI and ETI responses, respectively. At present, the metabolites activated by PTI and ETI and their roles and signalling pathways in plant immunity are not well understood. In this study, metabolomic analysis showed that ETI and PTI induced various flavonoids and amino acids and their derivatives in plants. Interestingly, both glutathione and neodiosmin content were specifically up-regulated by ETI and PTI, respectively, which significantly enhanced plant immunity. Further studies showed that glutathione and neodiosmin failed to induce a plant immune response in which PRRs/co-receptors were mutated. In addition, glutathione-reduced mutant gsh1 analysis showed that GSH1 is also required for PTI and ETI. Finally, we propose a model in which glutathione and neodiosmin are considered signature metabolites induced in the process of ETI and PTI activation in plants and further continuous enhancement of plant immunity in which PRRs/co-receptors are needed. This model is beneficial for an in-depth understanding of the closed-loop mode of the positive feedback regulation of PTI and ETI signals at the metabolic level.

Discovery of a novel nucleoside immune signaling molecule 2'-deoxyguanosine in microbes and plants.

INTRODUCTION: Beneficial microorganisms play essential roles in plant growth and induced systemic resistance (ISR) by releasing signaling molecules. Our previous study obtained the crude extract from beneficial endophyte Paecilomyces variotii, termed ZNC (ZhiNengCong), which significantly enhanced plant resistance to pathogen even at 100 ng/ml. However, the immunoreactive components of ZNC remain unclear. Here, we further identified one of the immunoreactive components of ZNC is a nucleoside 2'-deoxyguanosine (2-dG). OBJECTIVES: This paper intends to reveal the molecular mechanism of microbial-derived 2'-deoxyguanosine (2-dG) in activating plant immunity, and the role of plant-derived 2-dG in plant immunity. METHODS: The components of ZNC were separated using a high-performance liquid chromatography (HPLC), and 2-dG is identified using a HPLC-mass spectrometry system (LC-MS). Transcriptome analysis and genetic experiments were used to reveal the immune signaling pathway dependent on 2-dG activation of plant immunity. RESULTS: This study identified 2'-deoxyguanosine (2-dG) as one of the immunoreactive components from ZNC. And 2-dG significantly enhanced plant pathogen resistance even at 10 ng/ml (37.42 nM). Furthermore, 2-dG-induced resistance depends on NPR1, pattern-recognition receptors/coreceptors, ATP receptor P2K1 (DORN1), ethylene signaling but not salicylic acid accumulation. In addition, we identified Arabidopsis VENOSA4 (VEN4) was involved in 2-dG biosynthesis and could convert dGTP to 2-dG, and vne4 mutant plants were more susceptible to pathogens. CONCLUSION: In summary, microbial-derived 2-dG may act as a novel immune signaling molecule involved in plant-microorganism interactions, and VEN4 is 2-dG biosynthesis gene and plays a key role in plant immunity.

Hierarchical Pretraining on Multimodal Electronic Health Records.

Pretraining has proven to be a powerful technique in natural language processing (NLP), exhibiting remarkable success in various NLP downstream tasks. However, in the medical domain, existing pretrained models on electronic health records (EHR) fail to capture the hierarchical nature of EHR data, limiting their generalization capability across diverse downstream tasks using a single pretrained model. To tackle this challenge, this paper introduces a novel, general, and unified pretraining framework called MedHMP, specifically designed for hierarchically multimodal EHR data. The effectiveness of the proposed MedHMP is demonstrated through experimental results on eight downstream tasks spanning three levels. Comparisons against eighteen baselines further highlight the efficacy of our approach.

Neuro-epithelial-ILC2 crosstalk in barrier tissues.

Group 2 innate lymphoid cells (ILC2s) contribute to the maintenance of mammalian barrier tissue homeostasis. We review how ILC2s integrate epithelial signals and neurogenic components to preserve the tissue microenvironment and modulate inflammation. The epithelium that overlies barrier tissues, including the skin, lungs, and gut, generates epithelial cytokines that elicit ILC2 activation. Sympathetic, parasympathetic, sensory, and enteric fibers release neural signals to modulate ILC2 functions. We also highlight recent findings suggesting neuro-epithelial-ILC2 crosstalk and its implications in immunity, inflammation and resolution, tissue repair, and restoring homeostasis. We further discuss the pathogenic effects of disturbed ILC2-centered neuro-epithelial-immune cell interactions and putative areas for therapeutic targeting.

Microbial volatile organic compounds 2-heptanol and acetoin control Fusarium crown and root rot of tomato.

Some microbial volatile organic compounds (mVOCs) can act as antagonistic weapons against plant pathogens, but little information is available on the contribution of individual mVOC to biocontrol and how they interact with plant pathogens. In this study, the Bacillus subtilis strain N-18 isolated from the rhizosphere of healthy plants grown in areas where Fusarium crown and root rot (FCRR) of tomato occurs could reduce the 30% of the incidence of FCRR. Moreover, the volatile organic compounds (VOCs) produced by N-18 had inhibitory effects on Fusarium oxysporum f. sp. radicis-lycopersici (FORL). The identification of VOCs of N-18 was analyzed by the solid-phase microextraction coupled to gas chromatography-mass spectrometry. Meanwhile, we conducted sensitivity tests with these potential active ingredients and found that the volatile substances acetoin and 2-heptanol can reduce the 41.33% and 35% of the incidence of FCRR in tomato plants. In addition, the potential target protein of acetoin, found in the cheminformatics and bioinformatics database, was F. oxysporum of hypothetical protein AU210_012600 (FUSOX). Molecular docking results further predicted that acetoin interacts with FUSOX protein. These results reveal the VOCs of N-18 and their active ingredients in response to FORL and provide a basis for further research on regulating and controlling FCRR.

Silica nanoparticles protect rice against biotic and abiotic stresses.

BACKGROUND: By 2050, the world population will increase to 10 billion which urged global demand for food production to double. Plant disease and land drought will make the situation more dire, and safer and environment-friendly materials are thus considered as a new countermeasure. The rice blast fungus, Magnaporthe oryzae, causes one of the most destructive diseases of cultivated rice worldwide that seriously threatens rice production. Unfortunately, traditional breeding nor chemical approaches along control it well. Nowadays, nanotechnology stands as a new weapon against these mounting challenges and silica nanoparticles (SiO2 NPs) have been considered as potential new safer agrochemicals recently but the systematically studies remain limited, especially in rice. RESULTS: Salicylic acid (SA) is a key plant hormone essential for establishing plant resistance to several pathogens and its further affected a special form of induced resistance, the systemic acquired resistance (SAR), which considered as an important aspect of plant innate immunity from the locally induced disease resistance to the whole plant. Here we showed that SiO2 NPs could stimulate plant immunity to protect rice against M. oryzae through foliar treatment that significantly decreased disease severity by nearly 70% within an appropriate concentration range. Excessive concentration of foliar treatment led to disordered intake and abnormal SA responsive genes expressions which weaken the plant resistance and even aggravated the disease. Importantly, this SA-dependent fungal resistance could achieve better results with root treatment through a SAR manner with no phytotoxicity since the orderly and moderate absorption. What's more, root treatment with SiO2 NPs could also promote root development which was better to deal with drought. CONCLUSIONS: Taken together, our findings not only revealed SiO2 NPs as a potential effective and safe strategy to protect rice against biotic and abiotic stresses, but also identify root treatment for the appropriate application method since it seems not causing negative effects and even have promotion on root development.

A Novel Guanine Elicitor Stimulates Immunity in Arabidopsis and Rice by Ethylene and Jasmonic Acid Signaling Pathways.

Rice sheath blight (ShB) caused by Rhizoctonia solani is one of the most destructive diseases in rice. Fungicides are widely used to control ShB in agriculture. However, decades of excessive traditional fungicide use have led to environmental pollution and increased pathogen resistance. Generally, plant elicitors are regarded as environmentally friendly biological pesticides that enhance plant disease resistance by triggering plant immunity. Previously, we identified that the plant immune inducer ZhiNengCong (ZNC), a crude extract of the endophyte, has high activity and a strong ability to protect plants against pathogens. Here, we further found that guanine, which had a significant effect on inducing plant resistance to pathogens, might be an active component of ZNC. In our study, guanine activated bursts of reactive oxygen species, callose deposition and mitogen-activated protein kinase phosphorylation. Moreover, guanine-induced plant resistance to pathogens depends on ethylene and jasmonic acid but is independent of the salicylic acid signaling pathway. Most importantly, guanine functions as a new plant elicitor with broad-spectrum resistance to activate plant immunity, providing an efficient and environmentally friendly biological elicitor for bacterial and fungal disease biocontrol.