Breeding for disease resistance is an important objective in Brassica crop improvement. In this study, we evaluated the applicability of previously published molecular markers associated with downy mildew resistance in Brassica oleracea genebank material. Phenotypic resistance data were obtained from previous inoculation experiments with Hyaloperonospora parasitica isolates. A subset of 313 individual plants from 115 Brassica accessions, representing different resistance phenotypes at the cotyledon stage, was selected for molecular analysis. Five SSR markers associated with the resistance loci Pp523, Ppa207, and Ppa3 were tested: CB10028, CB10139, BoGMS0900, BoGMS0486, and BoGMS0624. The SSR markers amplified 29 alleles across the analysed material. However, marker–phenotype associations were not fully consistent across crop types and accessions. The highest informativeness was observed for CB10028 and BoGMS0900, whereas other markers showed stronger dependence on genetic background. Our results indicate that published resistance-linked markers can provide useful information for Brassica germplasm characterization, but they cannot be used as universal predictors of downy mildew resistance without further validation in defined genetic backgrounds and against individual pathogen isolates. The present marker evaluation is limited to cotyledon-stage resistance phenotypes, and further phenotyping would be required to assess marker applicability to true-leaf or adult-plant resistance.
Net blotch (NB), caused by Pyrenophora teres, is a major barley disease in Norway and worldwide. The two subspecies P. teres f. teres (Ptt) and P. teres f. maculata (Ptm) reproduce asexually via conidiospores and sexually via ascospores, the latter requiring opposite mating types. We analyzed the genetic diversity and structure of 339 Norwegian isolates and 61 globally collected isolates. Among the Norwegian collection, 325 (95.9
Understanding the introduction pathways of Phytophthora megakarya in newly established cacao plantations is crucial for improving black pod disease management. This study aimed to identify the sources and dispersal routes of P. megakarya in young cacao plantations in Central Cameroon. Three plantations established in 2006, located in two agro-ecological zones and initially free of primary inoculum, were monitored from the first disease outbreaks in 2009 until 2016. Isolates were collected from infected pods, while additional samples were obtained from soil and nearby river and run-off water using a baiting method. Genetic diversity was assessed using 14 polymorphic SSR markers. Relationships among multilocus genotypes (MLGs) were inferred using an eBURST-based Minimum Spanning Tree analysis. A total of 614 isolates were analysed, including 496 from pods, 106 from soil, and 12 from water. Overall genetic diversity was low, with 47 MLGs identified. Two dominant genotypes, MLG11 and MLG16, were consistently detected throughout the study period and across all sampling sources. Pathogenicity assays showed significant differences among a subset of genotypes, with MLG16 displaying the lowest pathogenicity, whereas savanna-associated genotypes were more aggressive. MLG11 and MLG16 were identified as founder genotypes in each agro-ecological zone. The findings indicate that exogenous inoculum was primarily introduced from neighbouring cacao plantations. However, the detection of P. megakarya in river and run-off water highlights the role of water-mediated dispersal in overcoming physical barriers. These results provide insights into local inoculum dynamics and support the development of improved disease management strategies in cacao-growing systems.
Crown rot diseases have become increasingly important in strawberry production following the withdrawal of key pesticides due to environmental and human health concerns. The principal causal agents, Macrophomina phaseolina and Fusarium oxysporum f. sp. fragariae, can persist for extended periods in infected crown tissues and residual plant material in soil, serving as inoculum sources for subsequent crops. In some regions, crop termination using drip fumigants has been adopted to simultaneously destroy residual strawberry plants and the pathogens within them. In this study, we evaluated microwave heating as a non-chemical alternative for crop termination and pathogen suppression in strawberry. Pot experiments were used to quantify the thermal sensitivity of the two pathogens within infected crown tissue in microwave-heated soil. The estimated LD50 and LD90 temperatures for M. phaseolina were 63.1 °C and 86.2 °C, and for F. oxysporum f.sp. fragariae 72.3 °C and 87.3 °C, respectively. A field experiment showed that heating a strawberry crop to 80–90 °C using microwaves terminated plants as effectively as a herbicide treatment (glufosinate-ammonium + triclopyr). Microwave treatment also reduced the viability of M. phaseolina and F. oxysporum f.sp. fragariae in infected strawberry crowns by an average of 97
Wilt disease in Acacia mangium plantations has become increasingly prevalent, threatening plantation health and productivity. Although Ceratocystis species are recognized as important wilt pathogens, the broader microbial communities associated with pruning wounds remain poorly understood. This study employed shotgun metagenomic sequencing to characterize fungal and bacterial communities colonizing pruning wounds of A. mangium subjected to three post-pruning treatments: pruning paint, fungicide, and untreated controls. Sapwood samples were analyzed to determine microbial taxonomic composition and functional gene profiles. Bacterial communities exhibited greater taxonomic variation than fungal communities, with paint-treated wounds supporting the highest bacterial diversity. Ceratocystis was detected in all treatments but showed a higher relative abundance in untreated than treated wounds. A total of 35 microbial genera were identified, reflecting the complexity of wound-associated microbial communities. Functional annotation revealed treatment-specific differences in metabolic pathways and enrichment of antimicrobial resistance and stress-response genes, particularly in paint- and fungicide-treated wounds, indicating distinct microbial adaptive responses. These findings demonstrate that post-pruning treatments alter the taxonomic composition and functional potential of wound-associated microbiomes and suggest that disease development may be influenced not only by pathogen presence but also by treatment-induced shifts in microbial community structure and function. This study provides new insights into the microbial ecology of A. mangium pruning wounds and supports the development of microbiome-informed approaches to disease management in plantation forestry.
Maize Curvularia Leaf Spot (MCLS), caused by C. lunata, severely reduces maize yield and deteriorates grain quality. In this study, in vitro toxicity assays, detached leaf inoculation tests and pot experiments were conducted to evaluate the control efficacy of mixtures of crude extract from B. amyloliquefaciens strain gfj-4 and chemical fungicides against maize curvularia leaf spot (MCLS). The results showed that strain gfj-4 achieved a mycelial inhibition rate of 73.58
The quarantine root-knot nematodes Meloidogyne chitwoodi and Meloidogyne fallax pose a significant phytosanitary risk to agricultural production, yet little is known about their ability to reproduce on strawberry. This study evaluated the host status of cultivated and wild Fragaria genotypes to both nematode species under greenhouse conditions. Seven strawberry genotypes were assessed in two independent experiments differing in inoculum density and duration, representing one and two nematode generations. Solanum lycopersicum cv. Moneymaker served as a susceptible control. Nematode reproduction was determined using the reproductive factor (RF = Pf/Pi). Tomato supported high levels of reproduction of both nematode species, confirming inoculum viability. In contrast, all Fragaria genotypes consistently showed RF values below 1. M. chitwoodi reproduced only at very low levels (maximum RF = 0.025), whereas M. fallax showed no reproduction after one generation and only very limited reproduction after two generations (maximum RF = 0.010). Although occasional eggs and second-stage juveniles were recovered from some strawberry plants, none of the evaluated genotypes supported nematode population increase. The results demonstrate that the tested Fragaria genotypes are poor hosts for both quarantine nematodes and may contribute to reducing population densities but should not be considered as eradication crops.
Stemphylium vesicarium is an emerging multi-host fungal pathogen that increasingly threatens European and global horticulture. Initially recognized as the causal agent of brown spot of pear and Stemphylium leaf blight of onion, the pathogen is now associated with diseases of other economically important crops, including spinach. Its broad host range, host-specialized pathotypes, host-specific toxins, and widespread fungicide resistance make disease management particularly challenging, often resulting in severe yield losses. The epidemiology of S. vesicarium is shaped by its polycyclic nature and dual reproductive strategy, with sexual ascospores colonizing alternative hosts in early spring and asexual conidia acting as the primary source of inoculum. The pathogen overwinters associated to crop residues, woody tissues, and alternative weed hosts, and can also spread through infected seeds, transplants, and thrips. Multilocus phylogenetics and whole-genome sequencing have clarified taxonomic ambiguities within Stemphylium, revealing substantial genetic diversity and complex population structures. In Europe, favourable climatic conditions, limited chemical control, fungicide-insensitive populations, and the lack of resistant cultivars in many crops underscore the urgent need for integrated disease management strategies. This review aims to give a valuable insight into the current knowledge on taxonomy, epidemiology, genetic diversity, toxin-mediated pathogenicity, and management of S. vesicarium, and identifies key research gaps to support sustainable disease control in European horticulture.
The application of herbicides in coffee agroforestry systems is increasing, yet the consequences for soil microbial suppressiveness against plant-parasitic nematodes remain poorly understood. We evaluated the impact of five herbicides – glyphosate, clethodim, flumioxazin, saflufenacil and pyroxasulfone – on the microbial-mediated suppressiveness of a herbicide-naïve coffee agroforestry soil against Meloidogyne paranaensis. In vivo bioassays quantified nematode infection in a model plant-tomato (Solanum lycopersicum L. cv. 'Santa Clara') through gall and egg counts per gram of root across two independent experiments. In vitro chemotaxis assays measured the behavioural attraction of second-stage juveniles (J2) to herbicide-exposed microbiomes. Bacterial community structure, alpha diversity, and beta diversity were assessed by 16S rRNA gene amplicon sequencing, with LEfSe analysis to identify differentially abundant taxa. Saflufenacil and pyroxasulfone significantly increased gall and egg densities relative to the untreated control, whereas glyphosate and clethodim showed no significant effect. Microbiomes exposed to saflufenacil and pyroxasulfone attracted J2 (chemotaxis index > 0.6), whereas glyphosate-treated and control microbiomes were repellent. Sequencing revealed herbicide-specific shifts in bacterial community composition and diversity, with suppression-associated genera (Chitinophaga, Bdellovibrio, Ramlibacter, Thermomonas) depleted and xenobiotic-tolerant genera (Sphingomonas, Cupriavidus) enriched under saflufenacil and pyroxasulfone. These findings demonstrate that herbicide selection directly modulates the suppressiveness of soil microbiomes towards M. paranaensis, highlighting the need for microbiome-aware weed management strategies in perennial agroforestry systems.
The interaction between Corinectria constricta and Pinus radiata has been studied in Chile since 2008; however, the mechanisms determining whether this fungus behaves as a pathogen or persists asymptomatically within host tissues remain unresolved. In this study, we experimentally evaluated the role of host entry pathway and host mechanical stress in delimiting the interaction outcome between C. constricta and P. radiata. Clonal seedlings were inoculated either through artificial wounds (invasive pathway) or natural openings (non-invasive pathway) and subjected to different levels of girdling-induced mechanical stress. Fungal presence was assessed in symptomatic and asymptomatic tissues using culture-based isolation and conventional PCR. Our results demonstrate that C. constricta consistently exhibits pathogenic behavior when entering through artificial wounds, leading to canker development, whereas non-wounded inoculation results in persistent, asymptomatic colonization detectable by molecular methods. Mechanical stress alone did not determine the interaction type but significantly amplified symptom severity once pathogenicity was established. These findings provide the first direct experimental evidence that the host entry pathway, rather than host stress, is the primary determinant of interaction outcome in the C. constricta–P. radiata pathosystem. This work advances understanding of opportunistic fungal behavior in forest trees and has direct implications for disease management in P. radiata plantations.
Dimethyl trisulfide (DMTS) exhibits potent antifungal activity against Alternaria alternata, yet its molecular mode of action has not been fully elucidated. In this study, we analyzed the key gene expression and phenotypic alterations in A. alternata after DMTS treatment to clarify its potential antifungal mechanism, and to provide insight into possible fungicidal targets. Given the pronounced antifungal activity of DMTS, transcriptomic analysis was performed to profile global gene expression changes in A. alternate following DMTS exposure, complemented by bioinformatics analysis and real-time fluorescent quantitative PCR (RT-qPCR) validation. A total of 2,321 differentially expressed genes (DEGs) were identified, including 934 up-regulated and 1,387 down-regulated genes. RT-qPCR validation confirmed that the gene expression trends were consistent with the transcriptomic data, supporting the reliability of the sequencing results. GO functional annotation and KEGG enrichment analysis revealed that the DEGs were associated with peroxisome formation, fatty acid β-oxidation, cellular ROS homeostasis, and energy metabolism pathways such as the tricarboxylic acid (TCA) cycle. In line with these transcriptional changes, DMTS exposure caused substantial intracellular ROS accumulation, impaired mitochondrial activity, reduced ATP production and DNA fragmentation, reflecting significant bioenergetic impairment and redox imbalance. Collectively, these findings suggest that DMTS inhibits fungal growth by disrupting peroxisome formation, mitochondrial function, and triggering excessive ROS-mediated oxidative damage. Simultaneously, DMTS impedes fatty acid β-oxidation and the TCA cycle, resulting in significant cellular ATP depletion. These combined effects ultimately inhibited the growth of A. alternata.
Banana bunchy top virus (BBTV; Babuvirus musae), an aphid-borne nanovirus, poses a major threat to global banana production, especially in India, the world's largest producer. This study surveyed, sequenced, and analyzed BBTV isolates from banana cultivars Dwarf Cavendish and Musa balbisiana in three Indian regions: North-Eastern India (NER), Karnataka, and Andaman Nicobar Islands. Complete genomes of the six circular DNA components (DNA-R, U3, S, M, C, N) were sequenced from 33 symptomatic samples. Phylogenetic analysis confirmed the isolates belong to the Pacific-Indian Ocean (PIO) group but showed significant nucleotide diversity. The BBTV DNA-U3 segment was identified as a recombination hotspot. Key findings include intercontinental recombination (e.g., a USA isolate with a major Indian parent) and potential inter-species recombination with Cardamom bushy dwarf virus (CBDV). These results establish recombination as a significant force in BBTV evolution in India, leading to a complex phylogeny and novel variants. This study highlights the need for continuous surveillance and diagnostics capable of detecting recombinant variants.
Paracidovorax citrulli (formerly known as Acidovorax citrulli), the causal agent of bacterial fruit blotch (BFB), is a major seed-borne pathogen of cucurbits and remains difficult to control using conventional management strategies. In this study, bacteriophages were isolated from watermelon-growing areas in Türkiye and evaluated for their potential as biological control agents against a local P. citrulli strain AC11. Six lytic bacteriophages were successfully isolated and characterized for their tolerance to different temperatures and pH conditions. The inhibitory effect of selected bacteriophages (DB_AC1, DB_AC6, and DB_AC7) on bacterial growth was evaluated individually and in combination using killing curve assays at different MOI values. DB_AC1 showed the strongest inhibitory effect, reducing bacterial growth by 44.3
Fusarium root rot is a prevalent soil-borne fungal disease that causes significant damage to tobacco yield and quality. However, research on disease resistance genes and their underlying mechanisms is limited. Therefore, this study aimed to investigate the resistance of 20 tobacco (Nicotiana tabacum. L) varieties to Fusarium oxysporum. Quantitative real-time PCR was performed to examine the tissue-specific expression patterns of 12 disease resistance-related genes in tobacco. In addition, changes in the expression of these 12 genes were assessed in two susceptible and two resistant varieties at 21 days post-inoculation with a Fusarium oxysporum isolate. NC82 and NC89 were classified as disease-resistant, whereas Yueyan 98 and Gexin No.3 were highly susceptible. Among the 12 genes, 10 exhibited the highest expression in the roots, and two showed the highest expression in the leaves. Importantly, significant differences in gene expression profiles were observed between the resistant and susceptible varieties at 21 days post-inoculation. Notably, hormone-related genes, such as NtPR1b, NtPR1a/c, and NtCHN50, were upregulated to a greater extent in susceptible varieties. In contrast, the mRNA levels of NtEFE26 and NtPAL were significantly downregulated in the resistant varieties post-inoculation with the pathogen, suggesting that these genes may be targets of Fusarium effectors. In addition, NtPR2, NtGST1, and NtCAT showed no significant changes in expression in resistant varieties, implying their limited role in disease resistance. This study is the first systematic screening of tobacco for resistance to Fusarium root rot and uncovered a novel expression pattern of defense-related genes, providing new insights into resistance mechanisms.
Wheat stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an airborne disease threatening global wheat production. Cultivar mixtures are a sustainable strategy to enhance field genotypic diversity. Further research is needed to investigate the synergistic relationship between disease control and yield effects, as well as impacts on pathogen population structure. We conducted field experiments using four wheat cultivars with different resistance levels (Mingxian 169, Liangxing 208, Zhengmai 21, Shannong 184) with monocultures as controls and 12 mixture combinations, to evaluate stripe rust epidemics and yield performance. We also genotyped Pst isolates using simple sequence repeat (SSR) markers to assess population genetic shifts. Our results demonstrated that the area under the disease progress curve (AUDPC) was lower in seven cultivar mixture combinations, indicating disease control advantages. The mixture of moderately susceptible and highly resistant cultivars (M12) achieved the highest relative disease control efficacy (43.42
Over the coming decades, the frequency of warm nights is expected to increase in several agricultural regions under climate change (CC) scenarios. Understanding how CC affects plant-pathogen interactions is crucial for predicting its impact on cereal crops, particularly Fusarium Head Blight (FHB). The present study evaluated the effect of warm nights (+3 °C) on the F. graminearum-barley pathosystem under field conditions, evaluating disease parameters, grain yield, mycotoxins, and malting quality in two commercial barley genotypes. Experiments were conducted in Argentina during the 2022 and 2023 seasons, with three treatments: natural conditions (no inoculation), inoculated with F. graminearum, and inoculated with increased night temperatures. Disease parameters were recorded 21 days post-inoculation, while grain yield, grain quality, mycotoxin concentration, and malting quality were evaluated post-harvest. In 2023, with high disease pressure, warm nights were associated with increased disease incidence (+10
Banana (Musa spp.) is a major staple and commercial crop in tropical and subtropical regions, yet its production is frequently constrained by bacterial wilt diseases. In 2018, a severe bacterial wilt-like outbreak was reported in a commercial banana plantation in Teluk Intan, Malaysia. Although Klebsiella variicola UTAR-BC1 was previously confirmed as a causal agent associated with this outbreak, primary isolation from symptomatic tissues also recovered multiple bacterial taxa, including Citrobacter farmeri, Enterobacter cloacae, Kosakonia radicincitans, and Phytobacter ursingii. The recurrent isolation of multiple bacterial taxa from symptomatic tissues raises the possibility of complex microbial associations during disease development, although their individual contributions to disease aetiology remain unclear. Among these isolates, K. radicincitans UTAR-BJ1 was selected for further investigation due to previous reports associating this species with banana bacterial wilt in Malaysia. Taxonomic placement of UTAR-BJ1 was assessed using multilocus sequence analysis (MLSA) of four housekeeping genes (atpD, rpoB, infB, and gyrB). Pathogenicity assays demonstrated that inoculation of healthy banana plantlets with UTAR-BJ1 consistently induced characteristic wilt symptoms under controlled inoculation conditions, whereas mock-inoculated controls remained asymptomatic. The bacterium was subsequently re-isolated from symptomatic tissues and molecularly confirmed as UTAR-BJ1, thereby fulfiling Koch’s postulates. This study provides the first experimental evidence that K. radicincitans strain, UTAR-BJ1, is capable of inducing wilt-associated symptoms in banana and highlights the need for further investigation into the role of K. radicincitans in banana wilt disease.
Berry crops are highly valued worldwide, yet systemic pathogens, especially viruses, pose major production constraints. Amongst all virus elimination methods, thermotherapy remains the most widely used because of its relative simplicity and broad applicability. This review evaluates thermotherapy for virus elimination in berry crops, synthesizing evidence from classic and modern studies. We condensed descriptive findings, highlighted mechanisms underlying virus replication suppression, and expanded the discussion on factors shaping efficiency. We also analyzed integration with complementary approaches such as meristem culture, chemotherapy, and cryotherapy. This review underscores the evolving role of thermotherapy as both a stand-alone and integrated approach to secure clean plants and ensure sustainable berry production under increasing pathogen pressures.
Monosporascus root rot and vine decline (MRRVD), caused by Monosporascus cannonballus, is a destructive soilborne disease threatening cucurbit production worldwide. However, effective integrated management strategies remain poorly defined. A two-year greenhouse study (2014/15 and 2015/16) was conducted to evaluate the individual and combined effects of organic amendments (0, 20, 40, and 60 t/ha), crop sequence, grafting, and soil solarization on MRRVD suppression and crop productivity. Agronomic parameters such as, yield, and fruit quality were monitored across two seasons, with a complementary pathogenicity assay characterizing virulence among 43 isolates. In the first season, high organic amendment significantly suppressed disease across all crops. For grafted melon, the 60 t/ha treatment reduced disease incidence by 42
Thymus capitatus, a Mediterranean aromatic species of the Lamiaceae family, produces an essential oil (EO) characterized by high levels of monoterpenic phenols, mainly carvacrol and thymol, which are widely recognized for their strong antimicrobial and antifungal properties. This review critically examines current knowledge on the chemical variability and antifungal potential of T. capitatus EO, with particular emphasis on its relevance to grapevine trunk diseases (GTDs). The EO has been extensively studied in vitro against a broad range of human and plant pathogenic fungi, including wood-inhabiting species associated with GTDs. However, its practical application in viticulture remains largely limited to laboratory and preliminary experimental studies, with scarce data available under in planta or vineyard conditions. Potential applications include pruning-wound protection and trunk delivery systems, but several constraints still need to be addressed, including chemical variability linked to geographical and environmental factors, formulation stability, compound persistence in woody tissues, phytotoxicity risks, and ecological impacts on vine-associated microbiota. This review synthesizes and discusses the phytochemical variability, antifungal activity, and mechanisms of action of T. capitatus EO, while highlighting current limitations, knowledge gaps, and future research priorities required to support its potential integration into sustainable GTD management strategies.
