Pathogenesis-related Research Articles

PbrATG6 modulates reactive oxygen species metabolism and interacts with PbrTLP15 synergistic enhancement of pear resistance to Botryosphaeria dothidea

Autophagy is vital for plant defense against pathogens, with ATG6 being a key gene in this process. At present, little has been reported on the potential function and molecular mechanisms of ATG6 mediated pathogen resistance in pear. This study investigates the function of the pear homolog of ATG6 (PbrATG6) in resistance to Botryosphaeria dothidea. PbrATG6 is expressed differentially in pear tissues and its expression increases upon infection. Overexpression of PbrATG6 enhances resistance in Arabidopsis and pear calli, while silencing it increases susceptibility. PbrTLP15, a pathogenesis-related protein belonging to the PR5 family, was found that interacts with PbrATG6 by a yeast two-hybrid screening. Yeast two-hybrid, luciferase complementation imaging, bimolecular fluorescence complementation assays and pull-down assays showed that PbrATG6 interacts with PbrTLP15. The transient silencing transgenic assays of PbrATG6 and PbrTLP15 revealed that PbrATG6 could cooperate with PbrTLP15 to regulate pear B. dothidea resistance. In addition, transcriptional analyses of autophagy key genes in pTRV-PbrTLP15 and transmission electron microscopy (TEM) assays also implied that PbrTLP15 does affect autophagy. Hence, PbrATG6 and PbrTLP15 may synergistically enhance pear B. dothidea disease resistance. It provides a new strategy for the study of autophagy in pear disease resistance and enriches the research on pear disease resistance mechanism.

Antimicrobial effect of green synthesized TiO<sub>2</sub> nanoparticles against Cercospora canesces growth in mung bean

Mung bean is one of the economically important leguminous crops generally grown in arid region of Pakistan. Mung bean grows best at 30-35℃ and is a nutrient enriched crop with higher amounts of starch (50%), proteins (18-25%), fat (3%) and fiber (3-4.5%). Many biotic factors affect crop production. Yield losses due to biotic factors are up to 40-80% in mung bean. Cercospora leaf spot (CLS) is very common disease in mung bean caused by hemi-biotrophic fungal pathogen Cercospora canescens. For sustainable agrocontrol there is need to develop alternative solutions for conventional methods. Green synthesized nanoparticles offer promising solution to mitigate adverse effect of agrochemicals and fungicides. In this review green synthesized TiO2 nanoparticles used to mitigate the disease severity by seed priming with 50mgL-1 and 150mgL-1 nanoparticles (NPs) suspension solution in mung bean. The result shows that 50mgL-1 Tio2-NPs inhibit fungal growth by 87.85% in in vitro and 74.07% in in vivo experiment. Tio2-NPs application improve root, shoot, leaf surface area, chlorophyll content, stomatal conductance and boost plant immunity by enhancing expression of the Pathogenesis-related (PR-1) gene in response stress. Therefore, present study indicates that green synthesized Tio2-NPs is an effective way to enhance the growth and productivity of mung bean by inhibiting C. canescens.

A Novel Secreted Protein of Fusarium oxysporum Promotes Infection by Inhibiting PR-5 Protein in Plant.

Fusarium oxysporum, an important soilborne fungal pathogen that causes serious Fusarium wilt disease, secretes diverse effectors during the infection. In this study, we identified a novel secreted cysteine-rich protein, FolSCP1, which contains unknown protein functional domain. Here, we characterized FolSCP1 as a secreted virulence factor that promotes the pathogen infection of host plants by inhibiting diverse plant defence responses. FolSCP1 interacted with the pathogenesis-related 5 (PR-5) protein SlPR5, a positive regulator of tomato plant immunity against multiple tomato pathogens, and effectively attenuated the antifungal activity of the tomato PR-5 protein. FoSCP1, a homologue of FolSCP1, was secreted by a F. oxysporum isolate from infected tobacco and targeted the tobacco PR-5 protein NtPR5 to suppress plant defence for further infection. In summary, our study revealed a fungal virulence strategy in which F. oxysporum secrete effectors that interfere with plant immunity by binding to the PR-5 protein of the host plant and inhibiting its biological activity, thereby promoting fungal infection.

Using salicylic acid-responsive promoters to drive the expression of jasmonic acid-regulated genes enhances plant resistance to whiteflies.

Jasmonic acid (JA) is an important phytohormone used to defend against herbivores, but it does not respond to whitefly feeding. Conversely, another phytohormone, salicylic acid (SA), is induced when plants are fed upon by whiteflies. JA has a better anti-whitefly effect than SA; however, there is limited research on how to effectively improve plant resistance by utilizing the different responses of these phytohormones to whitefly feeding. We discovered that protease inhibitors 8 (PI8) and terpene synthase 10 (TPS10) located downstream of the JA-regulated pathway in plants have anti-whitefly effects, but these two genes were not induced by whitefly feeding. To identify whitefly-inducible promoters, we compared the transcriptome data of tobacco fed upon by Bemisia tabaci with the control. We focused on pathogenesis-related (PR) genes because they are known to be induced by SA. Among these PR genes, we found that expression levels of pathogenes-related protein 1C-like (PR1) and glucose endo-1,3-beta-glucosidase (BGL) can be significantly induced by whitefly feeding and regulated by SA. We then engineered the whitefly-inducible promoters of BGL and PR1 to drive the expression of PI8 and TPS10. We found that compared with control plants that did not induce the expression of PI8 or TPS10, transformed plants expressing PI8 or TPS10 under the PR1 or BGL promoter showed a significant increase in the expression levels of PI8 and TPS10 after whitefly infection, significantly improving their resistance to whiteflies. Our findings suggest that using SA-inducible promoters as tools to drive the expression of JA-regulated defense genes can enhance plant resistance to whiteflies. Our study provides a novel pathway for the enhancement of plant resistance against insects. © 2024 Society of Chemical Industry.

SYNTAXIN OF PLANTS 132 underpins secretion of cargoes associated with salicylic acid signaling and pathogen defense.

Secretory trafficking in plant cells is facilitated by SNARE (soluble N-ethylamide-sensitive factor attachment protein receptor) proteins that drive membrane fusion of cargo-containing vesicles. In Arabidopsis, SYNTAXIN OF PLANTS 132 (SYP132) is an evolutionarily ancient SNARE that functions with syntaxins SYP121 and SYP122 at the plasma membrane. Whereas SYP121 and SYP122 mediate overlapping secretory pathways, albeit with differences in their importance in plant-environment interactions, the SNARE SYP132 is absolutely essential for plant development and survival. SYP132 promotes endocytic traffic of the plasma membrane H+-ATPase AHA1 and aquaporin PIP2;1, and it coordinates plant growth and bacterial pathogen immunity through PATHOGENESIS-RELATED1 (PR1) secretion. Yet, little else is known about SYP132 cargoes. Here, we used advanced quantitative Tandem Mass Tagging (TMT) mass spectrometry (MS) combined with immunoblot assays to track native secreted cargo proteins in the leaf apoplast. We found that SYP132 supports a basal level of secretion in Arabidopsis leaves, and its overexpression influences salicylic acid (SA) and jasmonic acid (JA) defence-related cargoes including PR1, PR2, and PR5 proteins. Impairing SYP132 function also suppressed defence-related secretory traffic when challenged with the bacterial pathogen Pseudomonas syringae. Thus, we conclude that, in addition to its role in hormone-related H+-ATPase cycling, SYP132 influences basal plant immunity.

Component-resolved diagnostics of fruit and vegetable allergy: precise identification and individualized treatment strategies

Vegetable and fruit allergies are common types of food allergies worldwide, most of them are triggered by primary sensitization to pollen. Most allergens in vegetables and fruits belong to a few cross-reactive proteins such as PR-10 proteins, profilins, and nsLTPs. The presence of these allergens in various plants can lead to widespread cross-reactive allergic responses. Component-resolved diagnostics (CRD) can improve diagnostic accuracy by precisely identifying specific allergenic proteins, aiding physicians in making more accurate treatment and management decisions, and reducing unnecessary food avoidance. This article, based on the "Molecular Allergology User's Guide 2.0 (MAUG 2.0)" issued by the European Academy of Allergy and Clinical Immunology (EAACI), analyzes the primary mechanisms, relevant allergens, and diagnostic and clinical management strategies for vegetable and fruit allergies. By detailing and analyzing these allergenic components, this article may help the healthcare professionals to deep the understandings of vegetable and fruit allergies, offer new perspectives and practical guideline for the research and treatment of these allergies, and promot the development of precise diagnostics and personalized treatment strategies.

Epsilon-poly-l-lysine and methyl jasmonate synergistically inhibit Pseudomonas tolaasii-caused brown spot disease in postharvest button mushroom (Agaricus bisporus)

The brown spot disease, caused by Pseudomonas tolaasii is a serious disease that significantly affects the quality of Agaricus bisporus. To develop a safe and effective method to protect mushrooms from disease, the effects of epsilon-poly-l-lysine (ε-PL) and methyl jasmonate (MeJA), either alone or in combination, on brown spot disease caused by P. tolaasii in A. bisporus were investigated. Our results showed that both ε-PL (100 mg L−1) and MeJA (100 μmol L−1) effectively reduced the incidence rate and disease index, inhibited the activity of polyphenol oxidase activated by P. tolaasii, and suppressed the production of malonaldehyde, and their combination achieved a more effective effect; the reason for this result was not due to their coordinated antibacterial activity in vitro, but rather the synergistic induction of disease resistance in mushrooms. The combined treatment of ε-PL and MeJA not only increased the content of pathogenesis-related proteins (PRs), the activities of defense enzymes and antioxidant enzymes, but also enhanced the activities of phenylpropanoid pathway-related enzymes and the accumulation of total phenolic and total flavonoid substances. Furthermore, the combined treatment was also more effective in increasing JA levels and the activities of lipoxygenase and allene oxide synthase compared to treatment with either ε-PL or MeJA alone. Correlation analysis further demonstrated the important role of defense-related enzymes and PRs as well as phenylpropanoid pathway-related enzymes and metabolites in the inhibition of ε-PL and MeJA alone or in combination on the incidence rate and disease index. Taken together, our results showed that ε-PL combined with MeJA treatment has good prospects for alleviating mushroom brown spot disease.

7076 Inhibiting Oxidosqualene Cyclase, An Enzyme In The Cholesterol Biosynthetic Pathway, Suppresses Lung Metastasis Of Triple-Negative Breast Cancer Cells

Abstract Disclosure: Y. Liang: None. S.M. Hyder: None. Triple-negative breast cancers (TNBC) lack ER, PR and Her2neu proteins that are commonly targeted in breast cancer therapies. As a consequence, women who suffer from TNBC have poor prognosis and limited treatment options, and are usually administered toxic, non-specific chemotherapeutic agents. Drug-resistance almost always occurs, leading to tumor metastasis, the main cause of patient death. New non-toxic therapeutic strategies to control metastasis of TNBC are urgently needed. Cholesterol is an essential structural and functional component of cell membranes that is necessary for the growth of both primary tumors and metastatic colonies that reside in distant organs. Therefore, inhibiting cholesterol production is an attractive therapeutic strategy. Treatment with statins, a class of cholesterol biosynthesis inhibitors that target HMGCoA-reductase, is associated with certain undesirable side effects; consequently, we targeted oxidosqualene cyclase (OSC), an enzyme that occurs downstream of HMGCoA-reductase in the cholesterol biosynthetic pathway, to disrupt tumor metastasis. Potent small molecule inhibitors of OSC have been identified. RO 48-8071 (4′-[6-(allylmethylamino)hexyloxy]-4-bromo-2′-fluorobenzophenone fumarate) (RO), has emerged as a useful chemotherapeutic agent for treating several forms of primary tumors. We developed a mouse model for studying lung metastasis using a MDA-MB-231 variant (LM2) TNBC cell line obtained from Dr. Massagué (Memorial Sloan-Kettering Cancer Center). These are aggressive cells, and injection of only 2 X 105 cells produces detectable lung metastatic colonies in approximately 4-6 weeks. We inoculated female nu/nu mice, 5-6 weeks old, with 2 X 105 MDA-MB-231/LM2 cells in 0.1 ml DMEM/F12 medium without serum via tail vein. Five days after tumor cell inoculation animals received 20 mg/kg (n=6), 40 mg/kg (n=7) RO (ip) or vehicle alone (n=7) every other day for two weeks. Animals were then sacrificed, and both lungs harvested and immediately fixed in Bouin’s fixative. Metastatic colonies on the lung surface were identified and counted under a dissecting microscope. Our study showed that RO effectively reduced lung metastasis without affecting animal weight. Compared with 56 + 7 colonies (Mean ± SEM) in controls given vehicle alone, RO significantly reduced lung metastatic colonies to 28 ± 5 in animals exposed to 20 mg/kg and 6 ± 1 in 40 mg/kg treated animals (p<0.05, ANOVA). Reduction in number of colonies in 40 mg/kg group was also significantly different from colonies counted in 20 mg/kg treated animals. Our study is the first to demonstrate that disruption of cholesterol biosynthesis in a model of human TNBC leads to reduced metastasis in lungs. Further studies will determine mechanisms through which RO suppresses TNBC metastasis to the lungs. Supported by Zalk Missouri Professor Endowment Funds. Presentation: 6/3/2024

7076 Inhibiting Oxidosqualene Cyclase, an Enzyme in the Cholesterol Biosynthetic Pathway, Suppresses Lung Metastasis of Triple-negative Breast Cancer Cells

Abstract Disclosure: Y. Liang: None. S.M. Hyder: None. Triple-negative breast cancers (TNBC) lack ER, PR and Her2neu proteins that are commonly targeted in breast cancer therapies. As a consequence, women who suffer from TNBC have poor prognosis and limited treatment options, and are usually administered toxic, non-specific chemotherapeutic agents. Drug-resistance almost always occurs, leading to tumor metastasis, the main cause of patient death. New non-toxic therapeutic strategies to control metastasis of TNBC are urgently needed. Cholesterol is an essential structural and functional component of cell membranes that is necessary for the growth of both primary tumors and metastatic colonies that reside in distant organs. Therefore, inhibiting cholesterol production is an attractive therapeutic strategy. Treatment with statins, a class of cholesterol biosynthesis inhibitors that target HMGCoA-reductase, is associated with certain undesirable side effects; consequently, we targeted oxidosqualene cyclase (OSC), an enzyme that occurs downstream of HMGCoA-reductase in the cholesterol biosynthetic pathway, to disrupt tumor metastasis. Potent small molecule inhibitors of OSC have been identified. RO 48-8071 (4′-[6-(allylmethylamino)hexyloxy]-4-bromo-2′-fluorobenzophenone fumarate) (RO), has emerged as a useful chemotherapeutic agent for treating several forms of primary tumors. We developed a mouse model for studying lung metastasis using a MDA-MB-231 variant (LM2) TNBC cell line obtained from Dr. Massagué (Memorial Sloan-Kettering Cancer Center). These are aggressive cells, and injection of only 2 X 10[5] cells produces detectable lung metastatic colonies in approximately 4-6 weeks. We inoculated female nu/nu mice, 5-6 weeks old, with 2 X 10[5] MDA-MB-231/LM2 cells in 0.1 ml DMEM/F12 medium without serum via tail vein. Five days after tumor cell inoculation animals received 20 mg/kg (n=6), 40 mg/kg (n=7) RO (ip) or vehicle alone (n=7) every other day for two weeks. Animals were then sacrificed, and both lungs harvested and immediately fixed in Bouin’s fixative. Metastatic colonies on the lung surface were identified and counted under a dissecting microscope. Our study showed that RO effectively reduced lung metastasis without affecting animal weight. Compared with 56 + 7 colonies (Mean ± SEM) in controls given vehicle alone, RO significantly reduced lung metastatic colonies to 28 ± 5 in animals exposed to 20 mg/kg and 6 ± 1 in 40 mg/kg treated animals (p<0.05, ANOVA). Reduction in number of colonies in 40 mg/kg group was also significantly different from colonies counted in 20 mg/kg treated animals. Our study is the first to demonstrate that disruption of cholesterol biosynthesis in a model of human TNBC leads to reduced metastasis in lungs. Further studies will determine mechanisms through which RO suppresses TNBC metastasis to the lungs. Supported by Zalk Missouri Professor Endowment Funds. Presentation: 6/3/2024

An Antisense Long Non-Coding RNA, LncRsn, Is Involved in Sexual Reproduction and Full Virulence in Fusarium graminearum.

Fusarium head blight (FHB), primarily caused by Fusarium graminearum, is a devastating crop disease that leads to significant declines in wheat yield and quality worldwide. Long non-coding RNAs (lncRNAs) are found to play significant functions in various biological processes, but their regulatory functions in the sexual reproduction and pathogenicity of F. graminearum have not been studied extensively. This study identified an antisense lncRNA, named lncRsn, located in the transcription initiation site region between the 5'-flanking gene FgSna and the 3'-flanking gene FgPta. A deletion mutant of lncRsn (ΔlncRsn) was constructed through homologous recombination. ΔlncRsn exhibited huge reductions in pathogen and sexual reproduction. Additionally, the deletion of lncRsn disrupted the biosynthesis of deoxynivalenol (DON) and impaired the formation of infection structures. RT-qPCR analysis reveals that lncRsn may negatively regulate the transcription of the target gene FgSna. This study found that lncRsn plays an important role in sexual and asexual reproduction, pathogenicity, virulence, osmotic stress, and cell wall integrity (CWI) in F. graminearum. Further characterization of pathogenesis-related genes and the reaction between lncRsn and protein-coding genes will aid in developing novel approaches for controlling F. graminearum diseases.

Callose and Salicylic Acid Are Key Determinants of Strigolactone-Mediated Disease Resistance in Arabidopsis

Research has demonstrated that strigolactones (SLs) mediate plant disease resistance; however, the basal mechanism is unclear. Here, we provide key genetic evidence supporting how SLs mediate plant disease resistance. Exogenous application of the SL analog, rac-GR24, increased Arabidopsis thaliana resistance to virulent Pseudomonas syringae. SL-biosynthetic mutants and overexpression lines of more axillary growth 1 (MAX1, an SL-biosynthetic gene) enhanced and reduced bacterial susceptibility, respectively. In addition, rac-GR24 promoted bacterial pattern flg22-induced callose deposition and hydrogen peroxide production. SL-biosynthetic mutants displayed reduced callose deposition but not hydrogen peroxide production under flg22 treatment. Moreover, rac-GR24 did not affect avirulent effector-induced cell death between Col-0 and SL-biosynthetic mutants. Furthermore, rac-GR24 increased the free salicylic acid (SA) content and significantly promoted the expression of pathogenesis-related gene 1 related to SA signaling. Importantly, rac-GR24- and MAX1-induced bacterial resistance disappeared completely in Arabidopsis plants lacking both callose synthase and SA. Taken together, our data revealed that callose and SA are two important determinants in SL-mediated plant disease resistance, at least in Arabidopsis.

Systematic expression analysis of cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 protein (CAP) superfamily in Arabidopsis.

The Cysteine-rich secretory proteins (CRISPS), Antigen 5 (Ag5), and Pathogenesis-related 1 (PR-1) protein (CAP) superfamily members are found in multiple eukaryotic organisms, including yeasts, animals, and plants. Although one of the plant CAP family genes, PR-1 is known to respond to pathogen infection in plants, the functions of other CAP family genes in Arabidopsis remain largely unknown. In this study, we conducted a comprehensive analysis of the similarities, loci, and expression patterns of 22 Arabidopsis CAP genes/proteins, providing a clue to elucidate their molecular functions. According to the promoter-β-glucuronidase (GUS) analysis, members of the Arabidopsis CAP family were expressed in various young tissues or organs, such as root and shoot meristems, reproductive tissues, and particularly at the lateral root initiation site before the formation of the lateral root primordium, with distinct expression specificity. In particular, CAP51, CAP52, and CAP53 were specifically expressed in the cortical cells at the lateral root developing regions, suggesting that these genes may function in lateral root development. Thus, the expression patterns of Arabidopsis CAP family genes suggest that CAP family proteins may have certain function in the expressed organs or tissues in Arabidopsis plant.

Biological Control of Anthracnose in Capsicum annuum Using Inoculants in Hydroponics: A Mechanistic Review

The Colletotrichum species that causes anthracnose poses a significant threat to the growth of Capsicum annuum, or ringer pepper, resulting in significant yield losses. Conventional produced control systems can give rise to ecological and economic difficulties, necessitating the need for alternative, workable solutions. This study explores the feasibility and parts of natural inoculants in controlling anthracnose ailment in Capsicum annuum filled in chipped away at hydroponics structures. As organic inoculants, we utilized a wide variety of useful microorganisms, such as Trichoderma harzianum, Bacillus subtilis, and mycorrhizal parasites. At various stages of the Capsicum annuum plant's development, these inoculants were incorporated into the supplement arrangements for tank farming. Anthracnose was observed and compared to untreated controls and synthetically treated plants in terms of its severity. Plants treated with natural inoculants show a significant reduction in sickness rate and severity, as shown by our findings. In fact, Trichoderma harzianum outperformed Bacillus subtilis and mycorrhizal parasites in terms of biocontrol productivity. Through a series of biochemical and sub-atomic tests, the fundamental instruments were examined. Natural inoculants, according to important discoveries, increase the plant's intrinsic safe reaction by causing fundamental obstruction. This is affirmed by the upregulation of pathogenesis-related (PR) characteristics and extended activity of shield impetuses like peroxidase (Unit), polyphenol oxidase (PPO), and phenylalanine antacid lyase (Amigo). In addition, the inoculants improved root development and supplement absorption, enhancing overall establish health and resistance to microorganisms. This study demonstrates that natural inoculants can be a reasonable and effective method for controlling anthracnose in Capsicum annuum grown in improved tank farms. In accordance with the goals of a potential agribusiness, incorporating these biocontrol specialists into aquafarming frameworks can increase crop productivity and reduce the use of compound pesticides.

CNGC20 plays dual roles in regulating plant growth and immunity in Brassica napus

Inflorescence architecture is determined by inflorescence length, branch angles and the density of siliques, which affects planting density, lodging resistance and mechanical operation in rapeseed. However, the molecular mechanisms controlling inflorescence architecture are poorly understood, restricting the progress of breeding varieties with ideal plant architecture in oilseed rape. In this study, we have identified and characterized a rapeseed inflorescence development mutant, reduced inflorescence length (ril), which exhibits determinate and shortened inflorescences, reduced plant height, compact branches, and increased silique density. Through BSA-seq and map-based cloning, we find that RIL encodes a cyclic nucleotide-gated channel 20 (BnaA01.CNGC20). A substitution of proline at the 304th position to leucine (P304L) was identified in the conserved transmembrane domain of BnaA01.CNGC20. This P304L substitution neither affects the subcellular localization and self-assembly of BnaA01.CNGC20, nor disrupts the interactions with BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 (BAK1), which interacts with CNGC20 and phosphorylates it to regulate Ca2+ channel stability. However, the P304L substitution increases channel activity and Ca2+ influx, which in turn induces immune responses such as cell death, H2O2 accumulation, upregulation of pathogenesis-related genes, and pattern-triggered immunity. The enhanced immunity improves the resistance to Leptosphaeria biglobosa and Sclerotinia sclerotiorum. Transcriptome analysis further revealed that CNGC20 plays dual roles in regulating plant growth and immunity via the brassinosteroid and auxin signaling pathways. The findings in this study provide deeper insights into the intricate relationship between cytosolic Ca2+ level and plant development and immunity, as well as the trade-off between immunity and the performance of yield-related traits in the heterozygous plants (+/ril), which may serve as a guide for balancing yield and disease resistance in oilseed rape breeding.

Bursaphelenchus xylophilus Venom Allergen-Like Protein BxVAP1, Triggering Plant Defense-Related Programmed Cell Death, Plays an Important Role in Regulating Pinus massoniana Terpene Defense Responses.

Bursaphelenchus xylophilus (pine wood nematode, PWN), a migratory plant-parasitic nematode, acts as an etiological agent, inflicting considerable damage to pine forests worldwide. Plant immunity constitutes a crucial factor in resisting various pathogenic invasions. The primary defensive responses of host pines against PWN infection encompass terpene accumulation, defense response-related gene expression, and programmed cell death. Venom allergen-like proteins (VAPs), as potential effectors, are instrumental in facilitating the successful colonization of PWNs. In this study, we investigated the inhibition of B. xylophilus VAP (BxVAP1) expression by RNA interference in vitro. Following BxVAP1 silencing, the reproduction rate and migration rate of the PWN population in Pinus massoniana decreased, the expression of the α-pinene synthase gene was induced, other terpene synthase and pathogenesis-related genes were inhibited and delayed, the peak times and levels of terpene-related substances were changed, and the degree of cavitation in P. massoniana was diminished. Transient expression of BxVAP1 in Nicotiana benthamiana revealed that BxVAP1 was expressed in both the cell membrane and nucleus, inducing programmed cell death and the expression of pathogen-associated molecular pattern-triggered immunity marker genes (NbAcre31 and NbPTI5). This study is the first to demonstrate that silencing the BxVAP1 gene affects host defense responses, including terpenoid metabolism in P. massoniana, and that BxVAP1 can be recognized by N. benthamiana as an effector to trigger its innate immunity, expanding our understanding of the parasitic mechanism of B. xylophilus.

Suppression of SlHDT1 expression increases fruit yield and decreases drought and salt tolerance in tomato.

Histone deacetylation, one of most important types of post-translational modification, plays multiple indispensable roles in plant growth and development and abiotic stress responses. However, little information about the roles of histone deacetylase in regulating inflorescence architecture, fruit yield, and stress responses is available in tomato. Functional characterization revealed that SlHDT1 participated in the control of inflorescence architecture and fruit yield by regulating auxin signalling, and influenced tolerance to drought andsalt stresses by governing abscisic acid (ABA) signalling. More inflorescence branches and higher fruit yield, which were influenced by auxin signalling, were observed in SlHDT1-RNAi transgenic plants. Moreover, tolerance to drought andsalt stresses was decreased in SlHDT1-RNAi transgenic lines compared with the wild type (WT). Changes in parameters related to the stress response, including decreases in survival rate, chlorophyll content, relative water content (RWC), proline content, catalase (CAT) activity and ABA content and an increase in malonaldehyde (MDA) content, were observed in SlHDT1-RNAi transgenic lines. In addition, the RNA-seq analysis revealed varying degrees of downregulation for genes such as the stress-related genes SlABCC10 and SlGAME6 and the pathogenesis-related protein P450 gene SlCYP71A1, and upregulation of the pathogenesis-related protein P450 genes SlCYP94B1, SlCYP734A7 and SlCYP94A2 in SlHDT1-RNAi transgenic plants, indicating that SlHDT1 plays an important role in the response to biotic and abiotic stresses by mediating stress-related gene expression. In summary, the data suggest that SlHDT1 plays essential roles in the regulation of inflorescence architecture and fruit yield and in the response to drought andsalt stresses.

Transcriptome and Metabolome Analyses Reveal Response Mechanisms to Alternaria brassicicola-Induced Black Spot Disease in Diverse Chinese Cabbage Genotypes

Chinese cabbage (Brassica rapa L. ssp. pekinensis) is an important food crop. However, its growth and development are commonly impacted by black spot disease. To examine the response mechanisms of Chinese cabbage to black spot disease, transcriptome and metabolome sequencing were performed on the leaves of Chinese cabbage genotypes J405 (resistant) and B214 (susceptible), 48 h post-infection (hpi) with Alternaria brassicicola. Expression of essential genes in the jasmonic acid, cytokinin, and auxin signaling pathways of both Chinese cabbage genotypes was inhibited. The expression of the pathogenesis-related protein 1 (PR1) gene mediated by the salicylic acid pathway is inhibited in the Chinese cabbage genotype B214. The basic endochitase B (CHIB) gene in the ethylene pathway of both Chinese cabbage genotypes was upregulated. The accumulation of reactive oxygen species in the disease spots of Chinese cabbage genotype J405 was greater than in genotype B214. The respiratory burst oxidase (RBOH) gene in the reactive oxygen species metabolic pathway was significantly upregulated in genotype J405, while no change was observed in genotype B214. We found that oxidation-reduction-related genes such as type-2 peroxiredoxin genes, NADPH-dependent thioredoxin reductase genes, glutathione peroxidase genes, and glutathione S-transfer genes were differentially expressed across both Chinese cabbage genotypes at 48 hpi. Metabolomics demonstrated that delta-tocopherol and S-hexyl glutathione were all downregulated in genotype J405, while they were upregulated in genotype B214. This approach also identified differential expression of genes in the carotenoid biosynthesis pathway, the glycinebetaine biosynthesis pathway, as well as in the specific sulfur glycoside metabolism pathway. These findings indicate that ethylene signaling is important in the hormone signaling regulatory network-mediated disease resistance and defense in Chinese cabbage. When facing pathogen infection, hormone transduction pathways associated with growth and development in Chinese cabbage are inhibited. The accumulation of reactive oxygen species and the outbreak of various secondary metabolites may endow the Chinese cabbage genotype J405 with increased resistance to black spot disease.

Regional propolis extracts suppress Fusarium fujikuroi and boost rice seedling growth and response against Bakanae disease

Bakanae, caused by Fusarium fujikuroi, is a serious seed-borne disease affecting rice production worldwide. Herein, we investigated the potential of propolis, a natural honeybee product, collected from three geographic locations in Egypt: North (Menofia), Middle (Cairo), and South (Sohag), and extracted with four different solvents (ethanol, olive oil, hexane, and water) as a sustainable eco-friendly alternative to control the Bakanae disease in rice. In vitro experiments showed that propolis extracts exhibited antifungal activity against F. fujikuroi and significantly suppressed its mycelial growth and sporulation. The antifungal activity of propolis extracts was associated with its chemical composition which varied depending on geographical origin, and the extraction solvents. Moreover, SEM-based analysis revealed that ethanolic extract of northern propolis prominently altered the microconidia morphology of F fujikuroi, which shrunken and seemed to lose their viability. These findings were further confirmed in vivo under greenhouse conditions. Soaking F fujikuroi-inoculated rice seeds in 1000 ppm of propolis extract significantly reduced the bakanae disease incidence, and disease severity index compared to mock-treated controls. Although infection with F fujikuroi induced the accumulation of H2O2, the application of propolis extracts alleviated oxidative stress and significantly reduced the H2O2 levels within infected rice seedlings. Moreover, propolis extracts enhanced the profile of enzymatic antioxidants (guaiacol-dependent peroxidase [POX] and polyphenol oxidase [PPO]) in F. fujikuroi-infected rice seedlings. Finally, Propolis extracts-treated rice seedlings exhibited higher transcript levels of three PTI-marker genes including nonexpressor of pathogenesis-related genes 1 (OsNPR1), WRKY transcription factor 21(OsWRKY21), and phenylalanine ammonia-lyase (OsPAL1), which are associated with systemic acquired resistance (SAR) and crucial for the plant's defense response against pathogens. Collectively, these findings suggest that propolis might be a promising sustainable, eco-friendly alternative to control bakanae disease and other fungal seed-borne phytopathogens due to its antifungal properties and ability to induce a complex multilayered defense system within infected plants.

Genome-wide survey of the bipartite structure and pathogenesis-related genes of Neostagonosporella sichuanensis, a causal agent of Fishscale bamboo rhombic-spot disease.

Bamboo resources have garnered significant global attention due to their excellent capacity for regeneration and high yield. Rhombic-spot disease, a substantial threat to fishscale bamboo (Phyllostachys heteroclada), is primarily caused by Neostagonosporella sichuanensis. This study first reported the genome assemblies and characteristics of two N. sichuanensis isolates using PacBio and Illumina sequencing platforms. The genomes of N. sichuanensis strain SICAUCC 16-0001 and strain SICAUCC 23-0140, with sizes of 48.0 Mb and 48.4 Mb, respectively, revealed 10,289 and 10,313 protein-coding genes. Additionally, they contained 34.99 and 34.46% repetitive sequences within AT-rich regions, with notable repeat-induced point mutation activity. Comparative genome analysis identified 1,049 contracted and 45 expanded gene families in the genome of N. sichuanensis, including several related to pathogenicity. Several gene families involved in mycotoxin metabolism, secondary metabolism, sterol biosynthesis and transport, and cell wall degradation were contracted. Compared to most analyzed necrotrophic, hemibiotrophic, and phaeosphaeriacous pathogens, the genomes of two N. sichuanensis isolates exhibited fewer secondary metabolite enzymes, carbohydrate-active enzymes, plant cell wall degrading enzymes, secreted proteins, and effectors. Comparative genomics analysis suggested that N. sichuanensis shares more similar characteristics with hemibiotrophic pathogens. Based on single carbon source tests, N. sichuanensis strains demonstrated a higher potential for xylan decomposition than pectin and cellulose. The proportion of cell wall-degrading enzyme effectors occupied a high proportion of the total effectors of the N. sichuanensis genomes. These findings provide valuable insights into uncovering the pathogenesis of N. sichuanensis toward the efficient management of rhombic-spot disease of fishscale bamboo.

Montmorillonite nanoclay triggers immunity responses in wheat against Puccinia striiformis f. sp. tritici, and suppresses uredospore germination

Puccinia striiformis f. sp. tritici causes the important disease, yellow rust of wheat (Triticum aestivum). Montmorillonite nanoclay (MNC) is naturally occurring and biodegradable. This study assessed in vitro anti-germination effects of MNC on P. striiformis uredospores. Application of MNC at 150 mg L-1 completely inhibited uredospore germination, and MNC at 100 mg L-1 reduced yellow rust severity in wheat plants by 89%. Expression of defense-related genes was increased after MNC treatment at 100 mg L-1, by 5.23-fold for jasmonate and ethylene-responsive factor 3 (JERF3), 4.89-fold for chitinase class II (CHI II), and 2.37-fold for pathogenesis-related protein 1 (PR1). Applying MNC at 100 mg L-1 also activated the antioxidant enzymes POD to 62.1 unit min-1 g-1 fresh wt, PPO to 21.6 units min-1 g-1 fresh wt, and CAT to 36.6 units min-1 g-1 fresh wt. MNC also enhanced phenolic content in wheat leaves (to 1489.53 mg 100 g-1 f. wt), and reduced lipid oxidation levels (to 5.6 μmol MDA g-1 fresh wt). MNC at 100 mg L-1 also mitigated damaging effects of P. striiformis infections on host leaf cell ultrastructure, increased leaf photosynthetic pigments, and increased wheat plant growth. These results show that MNC has potential as a natural control agent for yellow rust of wheat, although field testing of MNC is necessary before this material can be recommended for wheat production.