Search Results (179)

Background: Functional alleles of host plant susceptibility genes (S genes) can exacerbate the severity of diseases by enhancing pathogen compatibility. Genetic editing of the targeted host S genes has demonstrated remarkable efficacy in conferring broad-spectrum resistance across multiple crop species. We have previously identified a Golgi-localized Nucleotide Sugar Transporter 1 homolog (SlGONST1.1) in the host plant Solanum lycopersicum as a susceptibility gene towards late blight caused by Phytophthora infestans. Methods: In this study, we performed a detailed characterization of tissue-specific and P. infestans-inducible expression patterns of this gene, and the subcellular localization of its encoded protein product. Results: Similar to phenotypes of two reported Slgonst1.1 edited lines, two newly generated genetically edited lines of SlGONST1.1 demonstrated enhanced resistance against P. infestans without obvious growth and developmental abnormality. Phytohormonal quantifications and reactive oxygen species measurements showed that an Slgonst1.1 line had lower constitutive abscisic acid contents and depleted reactive oxygen species burst induced by pathogen-associated molecular pattern. Further comparative transcriptomic analyses revealed that the expression of defense-related genes is disproportionally up-regulated in the Slgonst1.1 line. Conclusions: In summary, our findings confirmed SlGONST1.1 as a functional host susceptibility gene towards late blight and shed light on the potential molecular mechanism underlying its function. Full article

Late blight, caused by Phytophthora infestans, is one of the most destructive diseases in potato cultivation. Chemical fungicides are currently the primary means of controlling it, but they pose significant issues, including environmental pollution and the development of resistant strains. Plant jiaosu (PJ), derived from the direct fermentation of various plants, plays a vital part in various fields such as environmental protection, agriculture, daily chemicals, and livestock. This study illustrates that PJ, fermented from lettuce leaves, significantly inhibits the growth of P. infestans. An isolated anti-oomycete bacterium, designated X-1, has 100% homology to Bacillus subtilis in the NCBI database, shown through 16S rDNA sequence analysis. B. Subtilis X-1 effectively inhibits the hyphal growth and sporangia germination of P. infestans, induces morphological changes in the hyphae, and can promote the growth of potato. PJ exerts a synergistic effect with the chemical fungicide Infinito (the main active ingredients are fluopicolide and propamocarb hydrochloride). In summary, this study provides a novel approach for the reutilization of fruit and vegetable waste and offers an environmentally friendly and effective alternative to chemical fungicides for controlling potato late blight. Full article

There is limited information on the genetic response of tomato cultivars to pathogens. This study investigated the genetic mechanism of tomato that confers tolerance against Phytophthora infestans (Ph) and Aspergills niger (Asp) infection using different tomato accessions. Also, the study examined the effect of Ph and Asp infection on the morphology and the chromosome number of the infected tomatoes. Thirty tomato seed accessions were grown in a screen house, using a complete randomized design in triplicate, and evaluated for tolerance to both pathogens using a disease severity rating scale of 1 (highly tolerant) to 6 (highly susceptible), while chromosome assessment was performed using Carnoy’s protocol. Morphological data of 28 characteristics were collected using an IPGRI descriptor, while variance components, genetic advance (GA), and heritability were estimated for treated tomatoes and controls using the R statistical program. Accession NHT0254b, which was highly tolerant to Ph (1.00 ± 0.00) and Asp (1.33 ± 0.58), was diploid (2n = 2x = 24). The Ph-treated NHT0343a was moderately susceptible (3.67 ± 2.31), with 2n = 2x = 23, while NGB00711 was moderately susceptible (4.33 ± 1.16) with 2n = 2x = 22 after Asp treatment, indicating aneuploidy. In Ph treatment, cumulative fruit weight (CFW) had the highest environmental variance (1509.57), while number of seeds (NS) showed the highest genotypic variance (8.22). In Asp treatment, NS exhibited the highest genetic advance (2.97), while CFW had the highest phenotypic variance (754.91). Heritability estimates showed that fruit length (63.0%), the size of core (65.0%), and number of chambers (60.0%) were tolerant to Ph, while only fruit length (56.0%) was tolerant to Asp in terms of yield characteristics. Thus, tolerant accessions and traits are recommended for selection and genetic improvement. Full article

This study aimed to investigate the biocontrol activity of rhizosphere isolates against late blight disease of tomatoes caused by the fungus Phytophthora infestans. A total of 30 rhizospheric bacterial isolates were evaluated for their antagonistic activity against P. infestans in vitro and in vivo. The results demonstrated that among the 30 isolates tested, six (RS65, RP6, RS47, RS46, RP2, and RS61) exhibited a highly significant inhibitory effect (p < 0.001) on the mycelial growth of P. infestans in vitro, with the inhibition rate exceeding 67%. Among the isolates, RS65 exhibited the highest inhibition rate at 78.48%. For antagonistic mechanisms, the results demonstrated that the six isolates exhibited significant enzymatic activity, including proteolytic, lipolytic, and chitinolytic activity, as well as the production of HCN, cellulase, and pectinase. Isolate RS65, which showed the highest inhibition rate, was further evaluated under greenhouse conditions. This investigation revealed significant differences in the severity of late blight between the control and the RS65 treatment. The control showed a severity level of 31.26%, whereas the RS65 treatment achieved the lowest severity of 16.54%. Molecular identification results indicated that the RS65 isolate (accession numbers PV208381) is a Bacillus genus with 99% proximity to Bacillus velezensis. This finding suggests that the Bacillus RS65 treatment could provide effective protection against P. infestans infection in tomato plants. These findings highlight the potential of Bacillus RS65 as a biocontrol agent in integrated disease management for tomato late blight. Full article

Several polyphenol-rich Terminalia species (Combretaceae) are known to accelerate wound healing. Recently, the Omani medicinal plant Anogeissus dhofarica (now Terminalia dhofarica) was attributed to the genus Terminalia based on phylogenetic studies. Leaves, bark, and extracts of T. dhofarica are traditionally used for various medicinal purposes, including wound treatment and personal hygiene. In the present study, the phytochemical profile of leaves from T. dhofarica was evaluated by ultra-high-performance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UHPLC-ESI-HRMS) and nuclear magnetic resonance (NMR) spectroscopy. Simple phenolics, polyphenolics (e.g., flavonoids and tannins) and their glucosides were characterized as major metabolite classes. In addition, 20 phenolics were isolated and structurally identified. Nine of these compounds were never described before for T. dhofarica. For the first time, we provide complete NMR data for 1-O-galloyl-6-O-p-coumaroyl-d-glucose (1). Biological screening demonstrated moderate efficacy against the Gram-negative bacterium Aliivibrio fischeri, the phytopathogenic fungus Septoria tritici, and the oomycete Phytophthora infestans. In summary, the data expand the knowledge of the phytochemistry of the underexplored species T. dhofarica and underscore its potential for therapeutic applications, particularly in the context of traditional medicine. Full article

Wheat leaf rust caused by Puccinia triticina (Pt) is a prevalent disease worldwide, seriously threatening wheat production. Pt acquires nutrients from host cells via haustoria and secretes effector proteins to modify and regulate the expression of host disease resistance genes, thereby facilitating pathogen growth and reproduction. The study of effector proteins is of great significance for clarifying the pathogenic mechanisms of Pt and effective control of leaf rust. Herein, we report a wheat leaf rust candidate effector protein Pt48115 that is highly expressed in the late stages of infection during wheat–Pt interaction. Pt48115 contains a signal peptide with a secretory function and a transit peptide that can translocate Pt48115 to the host chloroplasts. The amino acid sequence polymorphism analysis of Pt48115 in seven different leaf rust races showed that it was highly conserved. Pt48115 inhibited cell death induced by Bcl-2-associated X protein (BAX) from mice or infestans 1 (INF1) from Phytophthora infestans in Nicotiana benthamiana and by DC3000 in wheat, and its 145–175 amino acids of the C-terminal are critical for its function. Furthermore, Pt48115 inhibited callose deposition and reactive oxygen species accumulation in the wheat cultivar Thatcher, demonstrating that it is an effector that enhances Pt virulence by suppressing wheat defense responses. Our findings lay a foundation for future studies on the pathogenesis of Pt during wheat–fungus interaction. Full article

ADP-ribosylation is a reversible modification of proteins and nucleic acids, which controls major cellular processes, including DNA damage repair, cell proliferation and differentiation, metabolism, stress, and immunity in plants and animals. The involvement of ADP-ribosylation in the life cycle of Dictyostelium and some filamentous fungi has also been demonstrated. However, the role of this process in pathogenic oomycetes has never been addressed. Here, we show that the Phytophthora infestans genome contains two PARP-like protein genes (PiPARP1 and PiPARP2), and provide evidence of PARylation activity for one of them (PiPARP2). Using dsRNA-mediated RNA silencing of the PiPARP2 gene and chemical (pharmacological) inhibition of PARP activity by 3-aminobenzamide (3AB) PARP inhibitor, we demonstrate the critical functional role of ADP-ribosylation in Phytophthora mycelium growth. Virulence test on detached leaves also suggests an important role of ADP-ribosylation in Phytophthora host plant colonisation and pathogenesis. On a practical level, our data suggest that targeting the PARylation system may constitute a novel powerful approach for the management of Phytophthora diseases. Full article

Modern potato varieties from high-input, conventional farming-focused breeding programs produce substantially (up to 45%) lower yields when grown in organic production systems, and this was shown to be primarily due to less efficient fertilization and late blight (Phytophthora infestans) control methods being used in organic farming. It has been hypothesized that the breeding of potato varieties suitable for the organic/low-input sector should (i) focus on increasing nutrient (especially N) use efficiency, (ii) introduce durable late blight resistance, and (iii) be based on selection under low-input conditions. To test this hypothesis, we used an existing long-term factorial field experiment (the NEFG trials) to assess the effect of crop management practices (rotation design, fertilization regime, and crop protection methods) used in conventional and organic farming systems on crop health, tuber yield, and mineral composition parameters in two potato varieties, Santé and Sarpo mira, that were developed in breeding programs for high and low-input farming systems, respectively. Results showed that, compared to Santé, the variety Sarpo mira was more resistant to foliar and tuber blight but more susceptible to potato scab (Streptomyces scabies) and produced higher yields and tubers with higher concentrations of nutritionally desirable mineral nutrients but lower concentrations of Cd. The study also found that, compared to the Cu-fungicides permitted for late blight control in organic production, application of synthetic chemical fungicides permitted and widely used in conventional production resulted in significantly lower late blight severity in Sante but not in Sarpo mira. Results from both ANOVA and redundancy analysis (RDA) indicate that the effects of climatic (precipitation, radiation, and temperature) and agronomic (fertilization and crop protection) explanatory variables on crop health and yield differed considerably between the two varieties. Specifically, the RDA identified crop protection as a significant driver for Santé but not Sarpo mira, while precipitation was the strongest driver for crop health and yield for Sarpo mira but not Santé. In contrast, the effect of climatic and agronomic drivers on tuber mineral and toxic metal concentrations in the two varieties was found to be similar. Our results support the hypothesis that selection of potato varieties under low agrochemical input conditions can deliver varieties that combine (i) late blight resistance/tolerance, (ii) nutrient use efficiency, and (iii) yield potential in organic farming systems. Full article

Late blight is a destructive disease affecting tomato production. The identification and characterization of resistance (R) genes are critical for the breeding of late blight-resistant cultivars. The incompletely dominant gene Ph-2 confers resistance against the race T₁ of Phytophthora infestans in tomatoes. Herein, we identified Solyc10g085460 (RGA1) as a candidate gene for Ph-2 through the analysis of sequences and post-inoculation expression levels of genes located within the fine mapping interval. The RGA1 was subsequently validated to be a Ph-2 gene through targeted knockout and complementation analyses. It encodes a CC-NBS-LRR disease resistance protein, and transient expression assays conducted in the leaves of Nicotiana benthamiana indicate that Ph-2 is predominantly localized within the nucleus. In comparison to its susceptible allele (ph-2), the transient expression of Ph-2 can elicit hypersensitive responses (HR) in N. benthamiana, and subsequent investigations indicate that the structural integrity of the Ph-2 protein is likely a requirement for inducing HR in this species. Furthermore, ethylene and salicylic acid hormonal signaling pathways may mediate the transmission of the Ph-2 resistance signal, with PR1- and HR-related genes potentially involved in the Ph-2-mediated resistance. Our results could provide a theoretical foundation for the molecular breeding of tomato varieties resistant to late blight and offer valuable insights into elucidating the interaction mechanism between tomatoes and P. infestans. Full article

Late blight, caused by Phytophthora infestans, is a devastating disease of potato. Our previous work illustrated that scopolamine, the main bioactive substance of Datura extract, exerts direct inhibitory effects on P. infestans, but it is unclear whether scopolamine and Datura extract can boost resistance to late blight in potato. In this study, P. infestans is used to infect scopolamine-treated potato pieces and leaves, as well as whole potatoes. We found that scopolamine-treated potato is resistant to P. infestans both in vitro and in vivo. The treatment of 4.5 g/L scopolamine reduces the lesion size of whole potato to 54% compared with the control after 20 d of the infection of P. infestans. The disease-resistant substance detection based on the kit method shows that scopolamine triggers the upregulation of polyphenoloxidase, peroxidase, superoxide dismutase activities, and H₂O₂ contents in potato tubers, and the decline of phenylalanine ammonia lyase and catalase activity. A total of 1682 significantly differentially expressed genes were detected with or without scopolamine treatment through high-throughput transcriptome sequencing and the DESeq2 software (version 1.24.0), including 705 upregulated and 977 downregulated genes. Scopolamine may affect the genes functioning in the cell wall, membrane and the plant-pathogen interaction. The addition of Datura extract could directly inhibit the mycelial growth of P. infestans on rye plate medium. In addition, P. infestans was found to be resistant to late blight in potato pieces treated with Datura extract. Datura extract can also be utilized in combination with the chemical fungicide Infinito in field experiments to lessen late blight symptoms and enhance potato yield. To our knowledge, this is the first study to detect the induction of disease resistance by scopolamine, and it also explores the feasibility of Datura extract in potato disease resistance. Full article

Late blight of potato is caused by the pathogen Phytophthora infestans, which has been considered to be the most destructive disease affecting potato crops worldwide. In recent years, the use of antagonistic microorganisms to control potato late blight has become a green and environmentally friendly means of disease control, greatly reducing the use of chemical pesticides. To obtain antagonistic bacteria with a high biocontrol effect against potato late blight, a total of 16 antagonistic bacterial strains with an inhibition rate of more than 50% against P. infestans were screened from potato rhizosphere soil by double-culture method, among which the bacterial isolate (X3-2) had the strongest inhibitory activity against P. infestans, with an inhibition rate of 81.97 ± 4.81%, respectively, and a broad-spectrum inhibitory activity. The bacterial isolate (X3-2) was identified as Bacillus velezensis based on its 16S rDNA gene sequence and morphological as well as biochemical properties. The results of our in vitro experiments demonstrated that X3-2 was a potent inducer of resistance in potato tubers and leaflets against late blight. In greenhouse experiments, it was confirmed that the biological preparation X3-2 exhibits an anti-oomycete effect, demonstrating a significant control efficacy on potato late blight. Further analyses showed that the antagonistic substances of X3-2 were distributed both intracellularly and extracellularly. In addition, screening for plant-growth-promoting (PGP) traits showed that X3-2 has the ability to produce siderophores and secrete indole acetic acid (IAA). The findings from this research suggest that B. velezensis X3-2 exhibits promise as a biocontrol agent for managing late blight. In the future, the composition and mechanism of the action of its antimicrobial substances can be studied in depth, and field trials can be carried out to assess its actual prevention and control effects. Full article

The use of biological methods to control plant diseases has garnered attention due to their eco-friendly and economically viable nature. Trichoderma spp. are the most ubiquitous fungal saprophytes that can often grow as opportunistic symbionts, are eco-friendly, and are not reported to exert any environmental hazard. Soil-borne pathogens can significantly impact the yield of chilli and tomato crops. The study was conducted to explore the impact of various salts (NaCl, MgCl₂, CaCl₂, and KCl) and their concentrations (1%, 5%, 10%, and 15%) on the mycelial growth and sporulation of Trichoderma viride followed by its mass multiplication on diverse organic substrates like wheat seeds, wheat husks, mungbean seeds, maize seeds, rice seeds, pea seeds, sorghum seeds, banana peel, apple peel, pomegranate peel, citrus peel, tomato waste, chilli waste, spinach waste, cabbage waste, potato peel, onion peel, cucumber peel, carrot peel, used black tea leaves, used green tea leaves, poultry waste, and cow and goat dung. The study assessed the biocontrol potential of Trichoderma viride against important soil-borne pathogens in chilli (Pythium aphanidermatum, Phytophthora capsici, and Fusarium oxysporum) and tomato (Pythium aphanidermatum, Phytophthora infestans, and F. oxysporum) cropping in the pot and field experiments using saline and alkaline soils. Seed treatment with T. viride significantly enhanced the germination rates of both chilli and tomato crops, with sorghum being the most conducive substrate for mass-multiplying T. viride. The results revealed that lower salt concentrations minimally affected T. viride growth, while higher concentrations hampered both growth and sporulation. Optimal disease control and plant height were observed at a 20 mg concentration of T. viride, consequently applied in vivo using various application methods, i.e., seed treatment, root dip, irrigation, and mixed treatments (all the methods like seed treatment, root dip method, and irrigation method applied together) to manage soil-borne pathogens. Particularly, T. viride application through irrigation and mixed treatments demonstrated strong efficacy. These findings underscore the potential of T. viride application in saline and alkaline soils to manage soil-borne pathogens like Pythium, Phytophthora spp., and Fusarium spp. This study lays the foundation for the practical application of biocontrol agents, like T. viride, in Pakistani agricultural conditions. Moreover, there is a need for further exploration into the genetic mechanisms involved in disease inhibition and plant growth promotion, along with understanding the impact of T. viride on the metabolic pathways of host plants. Full article

Background: Tomatoes are renowned for their popularity and nutritional value across the globe, yet their production and quality face significant challenges from various biotic stresses in their growing environments. Kiwellin (KWL) has been implicated in plant disease resistance. However, our comprehension of this gene family in plants is still remarkably insufficient. Methods: We conducted a comprehensive genomic analysis of the KWL gene family in tomatoes. The tertiary structures of SlKWLs were predicted by AlphaFold2. EMBOSS was used for codon analysis. RNA-seq and RT-qPCR analysis were performed to explore the expression profile of SlKWLs. Results: Our findings identified 12 distinct SlKWL members distributed across four chromosomes within the tomato genome. By examining their gene structure, conserved motifs, functional domains, and phylogenetic relationships, we elucidated the complex evolutionary relationships and potential functions of these genes. Notably, we identified numerous cis-regulatory elements within the promoter regions of the SlKWL genes which are associated with responses to both abiotic and biotic stresses, as well as hormone signaling pathways. This finding strongly implies that SlKWLs are integral to plant growth and adaptation to diverse stress conditions. Furthermore, RNA-seq and RT-qPCR analysis revealed an upregulation of five SlKWLs expressed subsequent to Phytophthora infestans infection. Particularly, SlKWL2 and SlKWL3 exhibited substantially elevated expression levels, underscoring their active involvement in biotic stress responses. Conclusions: Collectively, these findings advance our comprehension of the SlKWL gene family and provide a robust foundation for future investigations into the roles of SlKWL genes in tomato stress responses. Full article

In continuously cropped strawberry soil, a large population of the fungivorous nematode, Aphelenchus avenae, was observed to increase significantly over time. This nematode, which feeds on pathogenic fungi affecting strawberries, has significant potential as a biocontrol agent. The purpose of this article is to discuss the nematode’s preference for fungi associated with strawberries and its impact on the growth of strawberry roots. With the exception of Trichoderma harzianum, most of the pathogenic fungi commonly found in strawberry soil, such as Fusarium oxysporum, Rhizoctonia solani, Verticillium, Phytophthora infestans, and Botrytis cinerea Pers. attracted A. avenae and supported their propagation. All treatments with A. avenae and the non-nematode control showed a consistent trend throughout strawberry development, indicating that a moderate amount of A. avenae does not adversely affect strawberry roots. Moderate and low levels of A. avenae significantly increased the activity of antioxidant enzymes, superoxide dismutase (SOD), and peroxidase (POD) in strawberry roots in all treatments during the entire growth stages. Also, the malondialdehyde (MDA) content of strawberry roots in all nematode treatments was lower than that in the no-nematode control. Despite an overabundance of A. avenae, which negatively affected the redox system balance of strawberry roots, A. avenae can protect the roots from pathogenic fungi by preventing infection and damage. These results lay the foundation for the potential use of A. avenae as a biological agent to control these pathogenic fungi in strawberry soil, in combination with the biological fungi (T. harzianum). Full article

Phytophthora infestans remains a major threat to global potato production. This study focused on characterizing and assessing the pathogenicity of P. infestans isolates on detached potato leaves and in greenhouse trials across four cultivars. Seven isolates were obtained from high potato-producing regions in the department of Nariño, Colombia. The isolates were analyzed using 12 microsatellite markers to determine genetic distances. Two genetically distinct isolates showed markedly different pathogenicity on detached leaves: isolate P00921 caused complete infection by day five, whereas P00321 showed no symptoms. These two isolates (P00921 and P00321) selected for having the greatest genetic distance and highest pathogenicity among the seven analyzed were further tested in a greenhouse setup on four potato cultivars using a randomized block design. Disease progression was monitored over nine days. The results indicated significant variations in pathogenicity linked to genetic diversity among isolates. Notably, Capiro and Margarita cultivars were more prone to severe disease than Suprema and Única. These findings highlight the complex nature of host–pathogen interactions and suggest the need for tailored approaches in disease management and cultivar selection. Full article