Search Results (142)

Contaminated seeds pose a major risk in hydroponic systems, as a single contaminated seed can compromise the entire setup. Effective decontamination strategies are essential to control seed-borne pathogens. Pecan shells, a byproduct comprising nearly 50% of the nut’s weight, have demonstrated antimicrobial properties against key pathogens. This study evaluated pecan shell extract (PSE) as a treatment to inactivate Listeria monocytogenes, Escherichia coli O157:H7, and Pseudomonas spp. on lettuce seeds and its effect on germination. Lettuce seeds were inoculated with L. monocytogenes strains (101 M, V7, LCDC, and Scott A) and treated with PSE (1:10 w/v) either by coating in sodium alginate or priming for 6 h (4 °C or room temperature). Hydropriming was used as a control. Additional trials with E. coli and Pseudomonas spp. tested PSE at 1:10, 1:20, and 1:30 w/v ratios. Priming at refrigeration significantly reduced Listeria levels. E. coli priming treatments showed significant reductions at 1:20 and 1:30 w/v. For Pseudomonas, priming at 1:20 showed the highest reduction. PSE priming also enhanced germination (88.3%), outperforming other treatments. These findings suggest PSE is a sustainable and effective seed treatment to reduce microbial contamination and enhance seed germination in hydroponic systems. Full article

A study was conducted to examine the effects of the spray application of nine antifungal products, including microbial-derived fungicides, plant-derived fungicides, and chemical fungicides, on the grass Achnatherum inebrians that was either host to Epichloë gansuensis (E+) or E. gansuensis-free (E−) and that was exposed to Blumeria graminis, the fungal pathogen causing powdery mildew. The Epichloë endophyte is a seed-borne mutualistic biotrophic fungus whose growth is fully synchronized with the host grass. Bl. graminis is a biotrophic pathogen that continually infects leaves and stems via conidia, the formation of appressoria, leading to the presence of haustoria in epidermal cells. Prior to fungicide application, the presence of endophytes significantly increased the resistance of A. inebrians to powdery mildew and was able to increase the chlorophyll content. However, the positive effects of the Epichloë endophyte on the plant were suppressed with the use of some fungicides and the increase in the number of sprays, but the reciprocal relationship between the Epichloë endophyte and the plant was not significantly disrupted. Full article

Climate change, soil degradation, and the spread of seed-borne pathogens pose serious challenges to global food security and agricultural sustainability. Although chemical seed treatment provides pathogen control, it poses environmental and health risks. This review analyses innovative seed treatment technologies, with particular emphasis on ozonation as an ecologically viable alternative. The mechanisms of action of ozone, its effects on seed germination, reduction of microbial contamination, and crop establishment are discussed. Chemical, physical, and biological treatment methods are comparatively evaluated, analyzing their effectiveness, environmental impact, and application limitations. Full article

Chickpea is a legume that grows in most parts of the world. It is negatively affected by abiotic and biotic factors like drought and fungal diseases, respectively. One of the most important soil-borne pathogens affecting chickpeas is Fusarium oxysporum f.sp. ciceris (Foc). Its population dynamics in the soil are affected by fluctuations in soil water content and host characteristics. For the last three decades, drought has been common in most areas of the world due to global warming. Drought stress decreases the quality and quantity of the chickpeas, particularly where soil-borne pathogens are the main stress factor for plants. The use of both drought-tolerant and disease-resistant cultivars may be the only option for cost-effective yield production. In this study, we screened the seeds of twelve chickpea genotypes WR-315, JG-62, C-104, JG-74, CPS-1, BG-212, ANNIGERI, CHAFFA, BG-215, UC-27, ILC-82, and K-850 for drought tolerance at increasing polyethylene glycol (PEG) concentrations (0-, 5-, 7.5-, 10-, 15-, 20-, 25-, 30- and 50%) to create drought stress conditions at different severities. The performances of genotypes that were previously tested in Foc resistance/susceptibility studies were assessed in terms of percentage of germination, radicle and hypocotyl length, germination energy, germination rate index, mean germination time, and vigor index in drought conditions. We determined the genotypes of C-104, CPS-1, and WR-315 as drought-susceptible, moderately drought-tolerant, and drought-tolerant, respectively. We then elucidated the stress levels of selected genotypes (20-day-old seedlings) at 0–15% PEG conditions via measuring proline and malondialdehyde (MDA) contents. Our findings showed that genotypes that were resistant to Foc also exhibited drought tolerance. The responses of chickpea genotypes infected with Foc under drought conditions are the next step to assess the combined stress on chickpea genotypes. Full article

Rice bakanae disease (RBD), a major threat in rice-cropping nations, can reduce rice yield and quality. As it is a seed-borne disease, effective seed detection is crucial. Loop-mediated isothermal amplification (LAMP) can rapidly and specifically amplify DNA at a constant temperature with high sensitivity. This research uses LAMP to develop rapid RBD pathogen detection systems. Primers were designed targeting the NRPS31 gene of Fusarium fujikuroi and conserved TEF1α sequences of Fusarium asiaticum, Fusarium proliferatum, and Fusarium andiyazi. These reactions at 60 °C for 60 min had a detection limit of 100 pg·μL⁻¹, and LAMP proved applicable in field trials. Full article

Curtobacterium species are increasingly recognized as plant pathogens and soil decomposers, but their prevalence and function as plant endophytes in aerial organs are less clear. In this study, we isolated six endophytic Curtobacterium species from the fruits, flower petals (previously unreported) and stem tissue of plants from diverse environments and examined their general characteristics. We found that all Curtobacterium endophytes belonging to three major Curtobacterium clusters—C. oceanosedimentum (a group not previously recognized as endophytic), C. luteum and C. flaccumfaciens—shared some common features. All or nearly all isolates tested were pigmented, displayed moderate salt tolerance and, surprisingly, were psychrotolerant, being able to grow at 6 °C. The exception was a fruit C. luteum isolate that appears to have evolved thermotolerance (up to 45 °C) instead as a likely adaptation to its environment. All isolates were able to metabolize starch and casein and solubilize inorganic phosphate, indicating conserved secreted hydrolase activity, but only isolates in the C. oceanosedimentum group were able to absorb and metabolize citrate. Finally, all endophytes tested were able to ferment the plant sugars sucrose and fructose, while they differed in their ability to use other sugars. Thus, this study documents common traits and adaptations in various Curtobacterium endophytes, and the presence of these isolates in floral and fruit organs implies the possible seed-borne inheritance of these isolates. Full article

Soil-borne diseases lead to high risk in crop production by diminishing the productivity and general health of the affected plants. Brassica plants are known to produce glucosinolates, which, upon decomposition, release bioactive isothiocyanates (ITCs). ITCs have attracted attention because of their biofumigation properties, effectively suppressing soil-borne pathogens and pests, promising natural solutions for managing soil-borne diseases. ITCs produced by Brassica plants or seed meal additives to soil have the ability to reduce soil-borne pests and diseases while increasing beneficial soil microbiota. Several researchers have indicated that ITCs can interfere with the life cycles of soil-borne pathogens and, at the same time, strengthen plant defense systems, which makes them a more environmentally friendly option than chemical pesticides. The breakdown of Brassica biomass has also been shown to stimulate beneficial microbial communities, which play a key role in nutrient availability and pathogen suppression. Studies indicate that this process enhances the availability of essential nutrients like sulfur and nitrogen in the soil, both of which are critical for plant growth and development. This review provides a comprehensive exploration of the role of Brassica ITCs in mitigating soil-borne diseases. We aim to consolidate current knowledge on ITC-mediated biofumigation, recommend strategies for enhancing its efficiency in practical applications, and highlight the need for future research to optimize its long-term effectiveness in sustainable agriculture. Full article

In the process of long-term co-evolution, endophytes and host plants benefit from and interact with each other, resulting in positive effects such as promoting plant growth, enhancing resistance, producing beneficial secondary metabolites, and negative effects such as carrying pathogens and producing toxins. In addition to the vegetative organs, plant seeds are also colonized by diverse endophytes and serve as vectors for the transmission of endophytes across plant generations. Seed endophytes, termed seed-borne endophytes (SBEs), have attracted much attention because these endophytes are involved in the assembly of the plant association microbiome and exert effects on progeny plants through vertical transfer. However, the importance of SBEs may still be underestimated. The present paper reviews the diversity, origin, and vertical transmission of seed endophytes, as well as their interaction and function with hosts, so as to provide a reference for future research and application of seed endophytes. Full article

Fusarium root rot, a destructive soil-borne fungal disease, necessitates eco-friendly biocontrol strategies. This study developed a microbial seed-coating approach using the antagonistic strain Paenibacillus polymyxa ZF129, formulated into a microencapsulated powder (10⁸ CFU/g) and a suspension (CS-ZF129). CS-ZF129 application enhanced cucumber resistance, achieving 46.30 ± 0.02% disease suppression while promoting root growth. The maximum increase in the fresh weight of the root in the promotion of rectangular growth was 47.16%. The colonization dynamics of ZF129 in the rhizosphere were systematically tracked, revealing its antagonistic correlation with Fusarium proliferation. An enzymatic activity analysis further uncovered the underlying regulatory mechanisms, demonstrating induced defense responses through pathogenesis-related protein activation. These findings highlight ZF129’s dual functionality as a biocontrol agent and a plant growth promoter, offering a sustainable strategy against soil-borne pathogens. Full article

Bacterial fruit blotch (BFB) is a highly destructive seed-borne and seed-transmitted disease caused by the Gram-negative bacterium Acidovorax citrulli that has caused substantial economic losses for the cucurbit industry in China. Despite its potential for economic damage, little is known about the bacterium’s molecular mechanisms of pathogenicity. Toxin–antitoxin (TA) systems are critical for the bacterial stress response. These systems are composed of two genes, toxin and antitoxin, that encode a stable toxin protein and a labile antitoxin protein, respectively. In this study, the genes for the putative HipBA TA system were identified in A. citrulli genomes through bioinformatic analysis. A series of molecular biology experiments have demonstrated that the HipBA TA system exists in A. citrulli Aac5. Furthermore, the transcription of hipA and hipB in A. citrulli Aac5 were induced by pH stress, chloramphenicol stress, and during plant infection. Overall, our results have revealed an active type II TA system, HipBA, in A. citrulli Aac5, and provided insights into its biological functions. These findings contribute to a better understanding of TA systems in plant pathogens. Full article

Fusarium stalk rot (FSR), a devastating soil-borne disease caused by Fusarium species, severely threatens global maize production through yield losses and mycotoxin contamination. Bacillus subtilis, a plant growth-promoting rhizobacterium (PGPR), has shown potential as a biocontrol agent against soil-borne pathogens, but its efficacy and mechanisms against maize FSR remain poorly understood. In this study, an identified strain of B. subtilis A3 was introduced to study its biological control potential against corn stalk rot. The bacteriostatic stability of the biocontrol strain was assessed, revealing that its inhibitory activity against F. graminearum remained consistent over five consecutive generations, indicating robust bacteriostatic stability. The strain also exhibited inhibitory effects on F. verticilliodes, F. proliferalum, and other pathogenic fungi, demonstrating it has broad-spectrum antibacterial activity. Indoor experiments showed that treatment with the biocontrol strain significantly increased plant height, stem diameter, and fresh weight, indicating a positive impact on corn growth. Additionally, the biocontrol strain A3 markedly reduced the lesion length of corn stalk rot, confirming its efficacy in controlling the disease. Field trials demonstrated that the growth of the A3-coated corn seeds was better than the control seeds, the control effect of FSR disease was 45.75%, and the yield increase was 3.6%. Microscopic observations revealed that the biocontrol strain A3 caused the hyphal tips of F. graminearum to swell and exhibit a beaded morphology, inhibiting normal growth. The volatile substances produced by A3 also showed significant antibacterial activity, with the antibacterial spectrum aligning with that of the biocontrol strain. Using headspace solid-phase microextraction and GC-MS, various antibacterial compounds were identified in the volatile substances. Analysis of root-associated microorganisms indicated that A3 significantly changed the microbial community composition. Co-occurrence network analysis revealed that A3-treated plants had fewer edges and lower negative correlations among bacterial communities. This study establishes the strong biocontrol potential of B. subtilis A3 against Fusarium stalk rot in corn, demonstrating its robust bacteriostatic stability, broad-spectrum antibacterial activity, positive impact on plant growth, and significant disease control efficacy, while also revealing its ability to alter root-associated microbial communities. These findings provide a foundation for further research into the mechanism of B. subtilis and its application in field biological control. Full article

A wide range of seed-borne and soil-borne plant pathogens belonging to various fungal and fungal-like species cause pre-emergence seed decay and post-emergence seedling blights of wheat and other small-grain cereal crops. To prevent the death of the seedlings, poor establishment and reduced stand of the crops, extensive crop rotations, planting good-quality seeds and seed treatments with fungicides are used on regular basis. This study is aimed at assessing the efficacy of pre-sowing seed treatments with cold atmospheric plasma for the disinfestation of winter wheat seed from economically important fungal and fungal-like pathogens. Uninoculated or surface-inoculated with Fusarium culmorum, Bipolaris sorokiniana or Pythium ultimum wheat seeds, the cultivar Madara was treated by cold plasma produced either by microwave torch (MW) or underwater diaphragm discharge (UW) with low power at very short treatment times, or remained untreated controls. As per the treatments, the seeds were sown in a ready-to-use growing medium comprising a mixture of light and dark moss peat (w:w) 90–95%, 5–10% perlite and 3–5 kg/m³ CaCO₃, having an electrical conductivity of 40 mS/m, pH (H₂O) of 5.5–6.5 and moisture content of 60–70%, filling in 250 × 250 × 70 mm aluminum flat seed trays (40 grains per tray, four trays per treatment). The plants were cultivated for 45 days in a growth chamber held at (20 ± 2) °C, set to a cycle of 8 h/night and 16 h/day under fluorescent light of 2000–3000 lux intensity. For each replicate, disease incidence (DI) was determined as the total percentage of missing, dead and apparently symptomatic plants. Seed treatment with a microwave plasma torch with a power of 16 W for 40 s significantly (p < 0.001) reduced seedling blights caused by F. culmorum, B. sorokiniana and P. ultimum by 46.8%, 51.0% and 77.3%, respectively, but limited the emergence of wheat seedlings by 15.9% on average. Simultaneously, the effectiveness of underwater discharge seed treatments reached an average of about a 60% reduction of seedling blight caused by F. culmorum and B. sorokiniana and about 37% of the disease caused by P. ultimum. Pre-sowing treatments with a MW plasma torch with an input power of 11 W and treatment time of 60, 90 or 120 s exposure also showed significant (p < 0.001) effects in controlling winter wheat seedling blights caused by the three pathogens. The effectiveness of the treatment increased with increasing the time period of exposure and reached full disease control (>80% reduction) for B. sorokiniana and P. ultimum seedling blights. This study demonstrated that pre-sowing treatment with a microwave plasma torch and underwater diaphragm discharge at a relatively low input power and short exposure time can be used for disinfestation and the effective control of seedling blights in winter wheat caused by seed-borne fungal pathogens, such as Fusarium culmorum and Bipolaris sorokiniana, and fungal-like oomycetes, such as Pythium ultimum. Full article

Pathogenesis from soil- and seed-borne fungi can limit the survival and growth of native seeds and seedlings. Fungicides can combat fungal pathogens, but in some studies, fungicide treatments were ineffective at improving seedling emergence over untreated seed. Such studies suggest that low fungal presence due to dry conditions may be the cause of fungicide ineffectiveness in some years and sites. This study tested whether a fungicide treatment’s effectiveness is indeed related to the amount of fungi in the soil. We compared the emergence and biomass produced from Pseudoroegneria spicata seed that was uncoated, coated with no active ingredient, and fungicide-coated, across five soil treatments promoting different levels of fungal biomass. For uncoated seed, both percent emergence and total biomass of seedlings were highest in autoclaved soil and declined when fungi were present, but the level of fungus did not impact emergence or biomass for fungicide-coated seed. When grown in autoclaved, untreated, or low-fungus soils, percent emergence and total biomass from fungicide-coated seeds were not significantly different from uncoated seeds. However, in medium- and high-fungus soils, the percent emergence and total biomass from fungicide-coated seeds were more than two times greater than uncoated seed (p < 0.05). These results indicate that fungicide treatments can be effective at increasing restoration success for P. spicata, but the effectiveness of the fungicide treatment depends on the microbial environment of the planting site. Full article

Soil-borne diseases, including charcoal rot (Macrophomina phaseolina) and collar rot (Sclerotium rolfsii), threaten global soybean production. Four fungicide combinations were tested as seed treatments at three concentrations (1, 1.5, and 2 g or ml per kg of seed) under controlled conditions to address the challenges posed by these diseases. Under controlled conditions, the combination of thiophanate methyl + pyraclostrobin at a rate of 2 mL/kg of seed significantly alleviated disease symptoms caused by both pathogens. Additionally, it enhanced shoot and root weights by over 50% in plants affected by S. rolfsii. Field trials were conducted for two years at two distinct locations to assess the efficacy of three selected combination seed treatment fungicides against M. phaseolina and S. rolfsii. Both inoculated and uninoculated controls were included for the comparison. Among the fungicides, thiophanate-methyl + pyraclostrobin and trifloxystrobin + penflufen proved the most effective for suppressing both diseases under epiphytotic field conditions across the years and locations. This study also highlighted the benefits of these chemical combinations in enhancing agronomic traits, maintaining yield, and ensuring the economic viability of soybeans. Full article

The global demand for legumes has grown significantly since the 1960s, due to their high protein content and environmental benefits. However, this growth could also facilitate the spread of seed-borne pathogens like Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff). Cff is a Gram-positive bacterium causing bacterial wilt in common beans and poses substantial challenges in regard to its detection and management, due to its long latent period and xylemic nature. Traditional diagnostic methods have proven insufficient, highlighting the need for innovative approaches. This study explores the potential of volatile organic compounds (VOCs) produced by Cff to be used as diagnostic markers to prevent the spread of seed-borne pathogens. First, we analyzed the VOCs emitted by different Cff strains in vitro, identifying a unique blend of five major VOCs. Subsequently, we verified the presence of these VOCs in vivo in artificially infected Cannellino beans. Phenylmethanol and 2-methoxy-4-vinylphenol emerged as key diagnostic markers, differentiating Cff from other bacterial pathogens of beans, such as Pseudomonas savastanoi pv. phaseolicola and Xanthomonas phaseoli pv. phaseoli. Our findings suggest that VOC fingerprinting offers a non-invasive, effective method for the early detection of Cff, even in asymptomatic seeds. This innovative approach holds significant promise for improving seed-borne disease management and supporting the development of practical diagnostic tools for field applications. Further research should aim to enhance the sensitivity and specificity of VOC-based diagnostics, facilitating the rapid and accurate screening of plant materials at ports of entry. This would contribute to the sustainability and health of leguminous crop production. Full article