Search Results (19)

Phosphonate-based fungicides are believed to control fungal diseases while also supplying nutrients to plants. However, opinions differ on whether they truly serve as nutrients for plants, and the residues of their transformation products have not yet been thoroughly evaluated or mathematically characterized. To address this gap, this study analyzed data from a two-factorial experiment investigating the effects of Agrifos 400 (potassium phosphonate) application. The experiment involved two soil types: red basalt soil and an organically enriched soil. Three-month-old pepper plants (Piper nigrum L.) were treated with Agrifos at application intervals of 10 and 20 days. The soils were inoculated with pathogenic Pythium spp., known to cause root rot diseases in plants. The soil chemical concentrations were analyzed every ten days, while plant growth parameters (height and leaf numbers) were recorded weekly. A mathematical model describing the fate of Agrifos transformation products was developed and parameterized using this experimental data. The results from the two-month experiment indicated that Agrifos did not enhance plant growth during this period. However, it led to a dramatic increase in soil phosphate (PO₄³⁻) levels, which could pose environmental risks. Despite this, the developed mathematical model demonstrated strong explanatory power, accurately capturing the observed data trends. Consequently, future research should consider integrating this model into broader biogeochemical cycle simulations, particularly those that incorporate chemical transport through soil water. Such integration would support more accurate predictions of the long-term environmental impacts of phosphonate-based products like Agrifos. Full article

Pepper (Capsicum annuum) production faces significant challenges from soil-borne pathogens, particularly Phytophthora capsici, which induces root rot and damping-off diseases. Management of this pathogen remains challenging owing to the scarcity of resistant cultivars and the ineffectiveness of chemical control methods. A single strain has been used to prevent pathogenic disease, and this approach limits the exploration of consortia comprising different genera. In this study, we isolated five bacterial strains (Bacillus sp. T3, Flavobacterium anhuiense T4, Cytobacillus firmus T8, Streptomyces roseicoloratus T14, and Pseudomonas frederiksbergensis A6) from the rhizosphere of healthy pepper plants. We then applied this 5-isolate synthetic microbial community (SynCom) to Capsicum annuum to evaluate its efficacy in improving pepper resilience against P. capsici. The SynCom members exhibited phosphate solubilization, indole-3-acetic acid production, catalase activity, siderophore synthesis, and strong antagonism against P. capsici. The SynCom reduced disease severity and enhanced the growth of pepper plants. Furthermore, the beneficial genera such as Bacillus, Fusicolla, and Trichoderma, significantly increased in the rhizosphere of pepper after the application of the SynCom. Microbial functional prediction analysis revealed that these microbial shifts were associated with nitrogen cycling and pathogen suppression. Our SynCom approach demonstrates the effectiveness of microbial consortia in promoting the growth of pathogen-infected plants by reprogramming the microbial community in the rhizosphere. Full article

Potassium has been identified as a vital nutrient for plant growth and functions. Studies have demonstrated its capacity to mitigate the severity of diseases by accelerating seed maturation and promoting robust root system development. In this study, we aimed to determine how increasing potassium doses affect the nutrient content, dry weight, root weight, and resistance to Rhizoctonia rot of the pepper plant. Pepper seedlings were used as plant material, and potassium sulfate was employed as the potassium fertilizer in this study. The experiment involved applying four different potassium doses (0, 50, 100, and 150 kg ha⁻¹) to pepper seedlings, along with RS0 (control) and RS1 (diseased plant) in four replicates. At the end of the study, analyses of the plants’ nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca), iron (Fe), manganese (Mn), copper (Cu), zinc (Zn), and boron (B) content, dry weights, and root weights were performed, in addition to disease assessments. An increase in N, P, K, Fe, and B content was observed with applied potassium doses, while a decrease in Mg content was noted. No significant change was detected in Cu content in pepper leaves, and the change in Mn content was not found to be statistically significant. An increase in plant dry weights was determined based on the applied treatments. The results indicated that plants subjected to potassium exhibited resistance to disease, an increase in root weights, and overall better conditions compared to samples without potassium. The best results in the experiments were achieved with the application of 150 kg ha⁻¹ K₂SO₄. It was observed that certain rates of potassium had positive effects on disease factors by suppressing Rhizoctonia rot and can be used for biological control. Full article

Anthracnose is a widespread plant disease affecting vegetables, flowers, crops, and fruit trees, causing significant economic losses. It occurs at various stages of pepper growth, leading to rotting and shedding in later stages. The aim of this study was to explore the relationship with anthracnose occurrence by analyzing the physicochemical properties and microbiota changes in the inter-root soil of pepper under different susceptibility levels to reveal the key microecological factors and dominant microbial populations and to provide reference for ecological control. Illumina Miseq sequencing was first used to evaluate the physicochemical properties and microbial taxa in pepper inter-root soil across different health statuses and identify key parameters associated with anthracnose. Subsequently, PICRUSt2 (systematic genetic Investigation of communities by Reconstruction of observed States 2) and FUNGuild (Fungi Functional Guild) V1.0 online platform were used to predict the activities of inter-root bacteria and fungi. The findings indicated that healthy peppers had significantly higher inter-root soil nutrient levels and enzyme activity compared to sensitive peppers. There were significant differences between their community structures. In alpha-diversity analysis, inter-root soil microbial richness and diversity were significantly higher in healthy peppers than in susceptible peppers. At the bacterial taxonomic level, the comparative prevalence of Acidobacteria in highly resistant plants, resistant plants, and susceptible plants decreased sequentially. At the genus level, the relative abundance of Vicinamibacteraceae and RB41 was markedly elevated in disease-resistant inter-root soils than in disease-susceptible soils. At the fungal level, the comparative prevalence of Ascomycetes in highly resistant plants, resistant plants, and susceptible plants increased sequentially. Differences in function are mainly manifested in apoptosis and mycelial development. Full article

Fusarium crown and root rot (FCRR), caused by Fusarium oxysporum f. sp. radicis-lycopersici (FORL), is an economically important disease that affects tomatoes worldwide and has become more prevalent in China in recent years. In 2021 and 2022, tomato plants in greenhouses in Hohhot, Inner Mongolia, were observed showing symptoms of stunting, premature loss of lower leaves, and root rot. Fungal pathogens were isolated from 20 infected tomato plants and identified based on morphological observation and DNA sequencing. Twelve isolates were consistently identified as Fusarium oxysporum f. sp. radicis-lycopersici (FORL) via an analysis of the ITS, TEF-1α, and pgx4 genes. This is the first report of FORL in Inner Mongolia, China. The isolates were examined for their pathogenicity by inoculating them on tomatoes, eggplants, peppers, and chickpeas. The fungicide sensitivity of the isolates was determined. Effective concentrations for 50% growth inhibition (EC₅₀) were measured using seven fungicides. The EC₅₀ values of tebuconazole and prochloraz were <1.0 μg·mL⁻¹, exhibiting the most effective inhibition among the fungicides tested. Additionally, FORL resistance screening of tomato germplasms was performed. One tomato variety was resistant to FORL, and the remaining 43 germplasm lines showed various levels of resistance. The rates of highly susceptible, moderately susceptible, susceptible, and moderately resistant germplasms accounted for 29.55%, 22.73%, 40.91%, and 4.55% of the 44 germplasms tested, respectively. Full article

This study utilized a diverse Capsicum accessions (5658) sourced from various species and geographical regions, deposited at the National Agrobiodiversity Center, Genebank. We employed 19 SNP markers through a Fluidigm genotyping system and screened these accessions against eight prevalent diseases of pepper. This study revealed accessions resistant to individual diseases as well as those exhibiting resistance to multiple diseases, including bacterial spot, anthracnose, powdery mildew, phytophthora root rot, and potyvirus. The C. chacoense accessions were identified as resistant materials against bacterial spot, anthracnose, powdery mildew, and phytophthora root rot, underscoring the robust natural defense mechanisms inherent in the wild Capsicum species and its potential uses as sources of resistance for breeding. C. baccatum species also demonstrated to be a promising source of resistance to major pepper diseases. Generally, disease-resistant germplasm has been identified from various Capsicum species. Originating from diverse locations such as Argentina, Bolivia, and the United Kingdom, these accessions consistently demonstrated resistance, indicating the widespread prevalence of disease-resistant traits across varied environments. Additionally, we selected ten pepper accessions based on their resistance to multiple diseases, including CMV, Phytophthora root rot, potyviruses, and TSWV, sourced from diverse geographical regions like Hungary, Peru, the United States, and the Netherlands. This comprehensive analysis provides valuable insights into disease resistance in Capsicum, crucial for fostering sustainable agricultural practices and advancing crop improvement through breeding strategies. Full article

The objective is to develop a portable device capable of promptly identifying root rot in the field. This study employs hyperspectral imaging technology to detect root rot by analyzing spectral variations in chili pepper leaves during times of health, incubation, and disease under the stress of root rot. Two types of chili pepper seeds (Manshanhong and Shanjiao No. 4) were cultured until they had grown two to three pairs of true leaves. Subsequently, robust young plants were infected with Fusarium root rot fungi by the root-irrigation technique. The effective wavelength for discriminating between distinct stages was determined using the successive projections algorithm (SPA) after capturing hyperspectral images. The optimal index related to root rot between each normalized difference spectral index (NDSI) was obtained using the Pearson correlation coefficient. The early detection of root rot illness can be modeled using spectral information at effective wavelengths and in NDSI, together with the application of partial least squares discriminant analysis (PLS-DA), least squares support vector machine (LSSVM), and back-propagation (BP) neural network technology. The SPA-BP model demonstrates outstanding predictive capabilities compared with other models, with a classification accuracy of 92.3% for the prediction set. However, employing SPA to acquire an excessive number of efficient wave-lengths is not advantageous for immediate detection in practical field scenarios. In contrast, the NDSI (R₄₄₅, R₄₃₃)-BP model uses only two wavelengths of spectral information, but the prediction accuracy can reach 89.7%, which is more suitable for rapid detection of root rot. This thesis can provide theoretical support for the early detection of chili root rot and technical support for the design of a portable root rot detector. Full article

To evaluate the potential of a bacterial strain as a fungal disease control agent and plant growth promoter, its inhibitory effects on phytopathogens such as Bipolaris sorokiniana, Botrytis cinerea, Colletotrichum capsici, Fusarium graminearum, F. oxysporum, Neocosmospora rubicola, Rhizoctonia solani, and Verticillium dahliae were investigated. The results showed that the inhibitory rates in dual-culture and sterile filtrate assays against these eight phytopathogens ranged from 57% to 83% and from 36% to 92%. The strain was identified as Bacillus velezensis based on morphological and physiological characterization as well as phylogenetic analyses of 16S rRNA and the gyrase subunit A protein (gyrA) regions. The results demonstrated that B. velezensis was able to produce fungal cell-wall-degrading enzymes, namely, protease, cellulase, and β-1,3-glucanase, and the growth-promotion substances indole-3-acetic acid (IAA) and siderophore. Furthermore, B. velezensis BV01 had significant control effects on wheat root rot and pepper Fusarium wilt in a greenhouse. Potted growth-promotion experiments displayed that BV01 significantly increased the height, stem diameter, and aboveground fresh and dry weights of wheat and pepper. The results imply that B. velezensis BV01, a broad-spectrum biocontrol bacterium, is worth further investigation regarding its practical applications in agriculture. Full article

Zanthoxylum armatum, a significant forest plant in southwestern China, is crucial for preserving soil and water resources. However, the presence of root rot disease has led to plant death, impacting the pepper sector. Effective control measures for this disease are still lacking. Rhizosphere microorganisms play a vital role in plant health by inhibiting plant pathogens and inducing plant resistance. This research aimed to isolate and characterize the pathogen responsible for root rot disease in Z. armatum. Comparative analysis of fungal and bacterial communities in the rhizosphere soil of healthy and diseased plants revealed Fusarium solani as the pathogenic fungus causing root rot disease. Diseased plants had a higher occurrence of Fusarium spp., while disease-free plants had a higher abundance of ecologically beneficial microbial communities that could potentially serve as biocontrol agents. Three bacterial strains (Bacillus subtilis, Bacillus amyloliquefaciens, and Bacillus siamensis) were identified as effective biocontrol agents, inhibiting the growth of the pathogenic fungus F. solani both in vivo and in vitro. This study deepens our understanding of the rhizosphere soil microbial community differences between diseased and healthy Z. armatum, providing potential biocontrol bacteria to enhance plant resistance against root rot disease. Full article

The use of rootstocks tolerant to water stress in pepper crops is a complementary technique for saving irrigation water without affecting yields by means of particular rootstock physiological traits, which changes the scion’s perception stress. The present study aimed to analyze the morphological and physiological adaptation of the ‘Cuerno’ pepper cultivar grafted onto tolerant rootstock NIBER^® subjected to capacitance sensor-based deficit irrigation. The stomatal conductance, relative water content and leaf water potential parameters were used to confirm the degree of crop stress. Leaf dry weight and root volume were higher in the grafted plants under the control irrigation and stress treatment conditions. Total fresh root biomass and root volume percentage of grafted plants under water stress were 24% and 33% higher, respectively, than the ungrafted plants. The grafted plants subjected to both water stress and control conditions had a higher marketable production than the ungrafted plants. The higher yields obtained using tolerant rootstocks were explained by the reduced blossom-end rot incidence. Full article

The plant-growth-promoting rhizobacteria (PGPR) B. subtilis PTS-394 has been utilized as a biocontrol agent (in a wettable powder form) due to its excellent ability to suppress tomato soil-borne diseases caused by Fusarium oxysporum and Ralstonia solanacearum. In this study, we evaluated the biocontrol efficiency of Bacillus subtilis PTS-394 wettable powder on pepper root rot in pot experiments and field trials. B. subtilis PTS-394 and its lipopeptide crude extract possessed excellent inhibition activity against Fusarium solani, causing pepper root rot; in an antifungal activity test B. subtilis PTS-394 wettable powder exhibited a good ability to promote pepper seed germination and plant height. The experiments in pots and the field indicated that B. subtilis PTS-394 wettable powder had an excellent control effect at 100-fold dilution, and its biocontrol efficacy reached 69.63% and 74.43%, respectively. In this study, the biocontrol properties of B. subtilis PTS-394 wettable powder on pepper root rot were evaluated and its application method was established. It was concluded that B. subtilis PTS-394 wettable powder is a potential biocontrol agent with an excellent efficiency against pepper root rot. Full article

Phytophthora capsici is one of the devastating pathogens, causing foliar blight, root rot, and fruit rot in peppers. Cinnamaldehyde (CA) is a natural compound coming from Cinnamomum cassia. The medicinal properties of CA have been widely identified. Limited knowledge is known about the application of CA in agriculture. In this study, CA significantly inhibited P. capsici, which further suppressed Phytophthora blights in both pepper seedlings and pepper fruits. Treatment with CA resulted in collapsed and fragmented hyphae, accompanying the increase in MDA (malondialdehyde) content and the decrease in intercellular glycerol content in hyphae. CA also inhibited the growth of wild type yeast. The yeast mutant ΔYvc1 with a deletion of Yvc1 (a Ca²⁺ transporter) showed decreased sensitivity to CA. The transformation of PcNCX1, a sodium/calcium exchanger from P. capsici, into ΔYvc1 restored its sensitivity to CA. The transformant carrying PcNCX1 also showed restored Ca²⁺ efflux upon CA treatment. RNA-seq analysis showed that CA treatments resulted in the down-regulation of a set of genes encoding for calcium-related proteins. Collectively, our study demonstrates that the antifungal activity of CA against P. capsici may be associated with PcNCX1-mediated Ca²⁺ efflux. Our results provide crucial insights into the antimicrobial action of CA. Full article

Pepper is vulnerable to soil-borne fungal pathogens such as Rhizoctonia solani and Fusarium oxysporum. The potential of beneficial rhizosphere microorganisms to control R. solani and F. oxysporum f.sp. capsici was evaluated in pepper plants. Paenibacillus polymyxa and Trichoderma longibrachiatum were isolated from rhizospheric soil samples of healthy pepper plants. In vitro, both isolates caused clear reductions in the radial growth of root rot and wilt pathogens. Scanning electron microscopy displayed lysis and abnormal shape of the pathogens in dual cultures with P. polymyxa and T. longibrachiatum. The incidence and severity of root rot and wilt diseases were significantly reduced in pepper plants treated with the growth-promoting fungi (PGPF isolates; Fusarium equiseti GF19-1, Fusarium equiseti GF18-3, and Phoma sp. GS8-3), P. polymyxa, or T. longibrachiatum in comparison to the control. Moreover, the induction treatments led to increased pepper growth compared with their control. The defense related gene (CaPR4) expression was shown to be significantly higher in the treated plants than in the control plants. In conclusion, the antagonistic isolates (P. polymyxa and T. longibrachiatum) and PGPF isolates have a clear impact on the prevention of root rot and wilt diseases in pepper plants incited by R. solani and F. oxysporum f.sp. capsici. The expression of the CaPR4 gene added to the evidence that PGPF isolates generate systemic resistance to pathogen infections. Full article

In recent years, quantitative trait loci (QTL) mapping approaches have been widely implemented to identify genomic regions affecting variation for different traits for marker-assisted selection (MAS). Meta-QTL analysis for different traits in chile peppers (Capsicum spp.) remains lacking, and therefore it would be necessary to re-evaluate identified QTL for a more precise MAS for genetic improvement. We report the first known meta-QTL analysis for diverse traits in the chile pepper QTLome. A literature survey using 29 published linkage mapping studies identified 766 individual QTL from five different trait classes. A total of 311 QTL were projected into a consensus map. Meta-analysis identified 30 meta-QTL regions distributed across the 12 chromosomes of Capsicum. MQTL5.1 and MQTL5.2 related to Phytophthora capsici fruit and root rot resistance were delimited to < 1.0 cM confidence intervals in chromosome P5. Candidate gene analysis for the P5 meta-QTL revealed functions related to histone methylation and demethylation, indicating the potential role of epigenetics for P. capsici resistance. Allele-specific markers for the meta-QTL will be developed and validated for MAS of P. capsici resistant lines. Altogether, results from meta-QTL analysis for chile pepper QTLome rendered further insights into the genetic architecture of different traits for this valuable horticultural crop. Full article

Symptoms of root stress are hard to detect using non-invasive tools. This study reveals proof of concept for vegetation indices’ ability, usually used to sense canopy status, to detect root stress, and performance status. Pepper plants were grown under controlled greenhouse conditions under different potassium and salinity treatments. The plants’ spectral reflectance was measured on the last day of the experiment when more than half of the plants were already naturally infected by root disease. Vegetation indices were calculated for testing the capability to distinguish between healthy and root-damaged plants using spectral measurements. While no visible symptoms were observed in the leaves, the vegetation indices and red-edge position showed clear differences between the healthy and the root-infected plants. These results were achieved after a growth period of 32 days, indicating the ability to monitor root damage at an early growing stage using leaf spectral reflectance. Full article