Search

The genus Phytophthora contains more than 100 plant pathogenic species that parasitize a wide range of plants, including economically important fruits, vegetables, cereals, and forest trees, causing significant losses. Global agriculture is seriously threatened by fungicide resistance in Phytophthora species, which makes it imperative to fully comprehend the mechanisms, frequency, and non-chemical management techniques related to resistance mutations. The mechanisms behind fungicide resistance, such as target-site mutations, efflux pump overexpression, overexpression of target genes and metabolic detoxification routes for fungicides routinely used against Phytophthora species, are thoroughly examined in this review. Additionally, it assesses the frequency of resistance mutations in various Phytophthora species and geographical areas, emphasizing the rise of strains that are resistant to multiple drugs. The effectiveness of non-chemical management techniques, including biological control, host resistance, integrated pest management plans, and cultural practices, in reducing fungicide resistance is also thoroughly evaluated. The study provides important insights for future research and the development of sustainable disease management strategies to counter fungicide resistance in Phytophthora species by synthesizing current information and identifying knowledge gaps. [ABSTRACT FROM AUTHOR]

Background: Plant fungal diseases present a major challenge to global agricultural production. Despite extensive efforts to develop fungicides, particularly succinate dehydrogenase inhibitors (SDHIs), their effectiveness is often limited by poor retention of fungicide droplets on hydrophobic leaves. The off-target losses and unintended release cause fungal resistance and severe environmental pollution. Results: To update the structure of existing SDHIs and synchronously realize the efficient utilization, we have employed a sophisticated supramolecular strategy to optimize a structurally novel SDH inhibitor (AoH25), creating an innovative supramolecular SDH fungicide (AoH25@β-CD), driven by the host-guest recognition principle between AoH25 and β-cyclodextrin (β-CD). Intriguingly, AoH25@β-CD self-assembles into biocompatible supramolecular nanovesicles, which reinforce the droplet/foliage (liquid-solid) interface interaction and the effective wetting and retention on leaf surfaces, setting the foundation for enhancing fungicide utilization. Mechanistic studies revealed that AoH25@β-CD exhibited significantly higher inhibition of SDH (IC50 = 1.56 µM) compared to fluopyram (IC50 = 244.41 µM) and AoH25 alone (IC50 = 2.29 µM). Additionally, AoH25@β-CD increased the permeability of cell membranes in Botryosphaeria dothidea, facilitating better penetration of active ingredients into pathogenic cells. Further experimental outcomes confirmed that AoH25@β-CD was 88.5% effective against kiwifruit soft rot at a low-dose of 100 µg mL-1, outperforming commercial fungicides such as fluopyram (52.4%) and azoxystrobin (65.4%). Moreover, AoH25@β-CD showed broad-spectrum bioactivity against oilseed rape sclerotinia, achieving an efficacy of 87.2%, outstripping those of fluopyram (48.7%) and azoxystrobin (76.7%). Conclusion: This innovative approach addresses key challenges related to fungicide deposition and resistance, improving the bioavailability of agricultural chemicals. The findings highlight AoH25@β-CD as a novel supramolecular SDH inhibitor, demonstrating its potential as an efficient and sustainable solution for plant disease management. [ABSTRACT FROM AUTHOR]

Background: Fungicides are an effective tool for protecting crops and maintaining a steady food supply. However, as pathogens continue to evolve, it is crucial to prolong the effectiveness of fungicides by delaying resistance development. A key strategy to achieving this is to combine or rotate fungicides with different modes of action. As fungicides lack specificity, they inevitably affect both pathogenic and non-pathogenic fungi when surrounding environments are unintentionally contaminated. Our study aims to investigate the effects of recommended application methods to prevent resistance development, specifically repeated-single fungicide, simultaneous mixture, and sequential applications on non-target soil fungi, and the subsequent impacts on important soil processes. We used fungicides with different modes of action on soil microcosms inoculated with fungi at varying levels of diversity (3, 5, and 8 species) isolated from a protected grassland. Results: We found that repeated treatments of individual isopyrazam and prothioconazole differentially inhibited fungal activity. Although mixture applications are considered more protectant against crop pathogen resistance than repeated application, our study revealed stronger negative effects of simultaneous application on saprobic fungi and consequently on soil processes. However, contrary to expectations, higher fungal diversity did not translate to improved soil function under these conditions. Conclusions: The simultaneous application of fungicides with different modes of action (MoA) has more pronounced non-target effects on soil compared to the individual or sequential application of fungicides. These non-target effects extend beyond the intended control of pathogenic fungi, impacting saprobic and beneficial soil microbes and the critical processes they drive. When fungicides are applied concurrently, microbial activities in the soil are significantly altered, even in soils with high microbial diversity. Our study emphasizes the importance of carefully considering the unintended consequences of fungicide use in agriculture. As we strive for a secure food supply, it is crucial to investigate the broader environmental impacts of these chemical interventions, including their effects on non-pathogenic fungi and overall soil health. [ABSTRACT FROM AUTHOR]

Potato production in Mexico is affected by Rhizoctonia solani, causing severe yield losses. The most important criterion for distinguishing R. solani isolates is differentiation by anastomosis groups (AGs). However, the limitations of traditional AG differentiation have prompted the use of DNA sequence analysis as a valuable tool for distinguishing AGs. This study aimed to determine the diversity of anastomosis groups and the aggressiveness of R. solani isolates collected from commercial potato fields in northern Sinaloa, Mexico. A total of 118 R. solani isolates were obtained from symptomatic sprouts and tubers collected from 32 commercial fields distributed in the municipalities of Ahome, Guasave and El Fuerte in northern Sinaloa, Mexico. Fifty-two representative isolates were selected for anastomosis group determination and pathogenicity tests. Phylogenetic analysis with rpb2 gene sequences clearly distinguished 30 isolates belonging to AG-3 PT and 22 isolates to AG-4 HGI. The aggressiveness of these R. solani isolates was evaluated using mini-tubers of potato cv. Fianna, and colonized rice grains were used as inoculum source. The disease severity caused by R. solani on potato plants was evaluated 40 days after emergence. Aggressiveness was estimated as the percentage of necrotic area on underground stems. The results revealed that all R. solani isolates were pathogenic and differences were observed in aggressiveness among the isolates. Of the total of 52 isolates evaluated, 7% were highly aggressive; 61% had intermediate aggressiveness; and 32% exhibited low aggressiveness. These findings regarding the diversity of anastomosis groups and the aggressiveness of R. solani isolates in northern Sinaloa are fundamental for subsequent epidemiology and fungicide resistance studies. [ABSTRACT FROM AUTHOR]

Ever since the first crops were domesticated over 10,000 years ago, pests and pathogens have wreaked havoc on crop production. Despite diverse threats from longstanding and emerging diseases, plants continue to play a central role in meeting humanity's requirements for calories and nutrients. In this review, we discuss historical advances made by plant pathologists and breeders that have helped keep many plant diseases at bay. We focus predominantly on fungal diseases of five food crops—rice, wheat, maize, soybean and potato—that provide the bulk of calories consumed globally. We cover such historical triumphs in plant pathology as (i) advanced knowledge of fungal biology revolutionizing disease management strategies, (ii) integration of genetics by the 'wheat wizard' Rowland Biffen and others transforming the landscape of resistance breeding and (iii) the advent of modern fungicides—from a sinking ship in the 1660s—leading to dramatic yield enhancements. We also discuss (iv) the potential for emerging biocontrol agents to holistically promote plant health and yield. Today, the high homogeneity of crops in modern agricultural systems exacerbates yield losses due to disease by increasing pest/pathogen transmission rates and eroding natural spatial barriers to pest/pathogen dispersal. Meanwhile, climate change is altering the compositions of global pest and pathogen populations and expanding pest/pathogen territories with unpredictable consequences. As we look to the future, the strength of the plant pathology community remains central to developing innovative solutions to tackle these complex and expanding threats to plant health and secure a plentiful food supply. [ABSTRACT FROM AUTHOR]

Australia is one of the largest barley exporters in the world, with Western Australia accounting for some 40% of national production. The crop is predominantly grown in the south and south‐west of the state in winter and spring, where temperate conditions and higher rainfall levels are more suited to barley than northern and eastern regions. Between 2007 and 2013, prolonged outbreaks of barley powdery mildew (BPM) occurred. This was brought about by a combination of the extensive use of susceptible cultivars and an over‐reliance on a small number of single mode‐of‐action demethylation inhibitor fungicides, which select for mutations in the C14α‐demethylase (Cyp51A) gene. This review highlights the steps taken to reduce losses to BPM, breeding efforts to introduce resistance into cultivars and the success of pre‐breeding research to find new and durable resistance genes. We also draw comparisons with powdery mildew in Australian wheat, where similar factors are leading to substantial outbreaks. [ABSTRACT FROM AUTHOR]

Corn (Zea mays L.) is a major irrigated crop in the Texas High Plains (THP). Inadequate precipitation, declining groundwater resources, and inevitable seasonal drought in the area have led to a greater number of studies on crop hybrids, water regimes, and other yield-enhancing techniques. A four-year field study was conducted to investigate the effect of foliar fungicide timing on corn grain yield, grain moisture, and grain test weight under different irrigation regimes. A fungicide containing QoI + DMI was applied to four to six corn hybrids each year at various growth stages (V5, R1, and V5 + R1). For all years, corn plants were grown under three irrigation regimes to meet the seasonal evapotranspiration (ET) requirements of 50% (I50), 75% (I75), and 100% (I100). Hybrid response to the timing of fungicide application and irrigation regime was not consistent over the years. However, in 2 of the 4 years, timing of fungicide application resulted in yield differences among the hybrids, especially at I75 and L100. For those years, the fungicide applied at R1 resulted in a higher grain yield, grain moisture, and grain test weight followed by the fungicide applied at V5 + R1. Results showed that hybrids reacted differently to the foliar fungicide based on the availability of water under disease-free conditions. This study further revealed that irrigation water could be reduced from I100 to I75 with a limited (5.6% in 2011, 11.3% in 2012, 1.3% in 2013, and 0.3% in 2014) yield penalty in the THP region. [ABSTRACT FROM AUTHOR]

Fungicides are an indispensable tool in plant disease control. Various modes of action (MOAs) have been identified in different fungicides to suppress plant pathogens. The combined use of fungicides with distinct MOAs has been recommended to prevent the development of pathogen resistance. In studying MOAs, metabolomics has been proven to be a robust and high-throughput method. Because metabolites are unique and distinct depending on the biological activities of an organism, MOAs can be identified and classified by establishing metabolic fingerprinting and metabolic profiles. Similarly, if fungicide resistance is developed in a pathogen, the metabolome will change, which can be identified. In this review, we have discussed the principles and advanced applications of metabolomics in the study of MOAs and resistance mechanisms of fungicides, and the potential of metabolic data in understanding the interaction between fungicides and pathogens. Challenges are also discussed in the application of metabolomics, improvement of the study on the mechanism of fungicides in their functions against pathogens and advancing the development of novel fungicides. [ABSTRACT FROM AUTHOR]

BACKGROUND: Rice sheath blight caused by Rhizoctonia solani is a severe threat to the yield and quality of rice. Due to the unscientific abuse of common fungicides causing resistance and environmental issues, the development of new fungicides is necessary. In this study, we used citral as the lead compound, designed and synthesized a series of novel citral amide derivatives, and evaluated their antifungal activity and mode of action against R. solani. RESULT: Bioassay results indicated that the antifungal activities of most citral amide derivatives against R. solani were significantly improved compared to citral, with EC50 values ranging from 9.50–27.12 mg L−1. Among them, compound d21 containing the N‐(pyridin‐4‐yl)carboxamide group exhibited in vitro and in vivo fungicidal activities, with curative effects at 500 mg L−1 as effectively as the commercial fungicide validamycin·bacillus. Furthermore, d21 prolonged the lag phase of the growth curve of R. solani, reduced the amount of growth, and inhibited sclerotium germination and formation. Mechanistically, d21 deformed the mycelia, increased cell membrane permeability, and inhibited the activities of antioxidant and tricarboxylic acid cycle (TCA)‐related enzymes. Metabolome analysis showed the abundance of some energy‐related metabolites within R. solani increased, and simultaneously the antifungal substances secreted by itself reduced. Transcriptome analysis showed that most genes encoding ATP‐binding cassette (ABC) transporters and peroxisomes upregulated after the treatment of d21 and cell membrane destruction. CONCLUSION: This study indicates that novel citral amide derivatives possess antifungal activity against R. solani and are expected to develop an alternative option for chemical control of rice sheath blight. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Background: The Fusarium head blight caused by Fusarium graminearum results in reduced crop yields and the potential for vomitoxin contamination, which poses a risk to both human and livestock health. The primary method of control relies on the application of chemical fungicides. Results: The current study found that the tebuconazole sensitivity of 165 F. graminearum isolates collected from the Huang-Huai-Hai region of China between 2019 and 2023 ranged from 0.005 to 2.029 µg/mL, with an average EC50 value of 0.33 ± 0.03 µg/mL. The frequency distribution conformed to a unimodal curve around the mean, and therefore provides a useful reference for monitoring the emergence of tebuconazole resistance in field populations of F. graminearum. No cross-resistance was detected between tebuconazole and other unrelated fungicides such as flutriafol, propiconazole and fluazinam, but there was a clear negative cross-resistance with triazole fungicides including fludioxonil, epoxiconazole, hexaconazole, and metconazole. Analysis of five tebuconazole-resistant mutants produced under laboratory conditions indicated that although the mycelial growth of the mutants were significantly (p < 0.05) reduced, spore production and germination rates could be significantly (p < 0.05) increased. However, pathogenicity tests confirmed a severe fitness cost associated with tebuconazole resistance, as all of the mutants completely loss the ability to infect host tissue. Furthermore, in general the resistant mutants were found to have increased sensitivity to abiotic stress, such as ionic and osmotic stress, though not to Congo red and oxidative stress, to which they were more tolerant. Meanwhile, molecular analysis identified several point mutations in the CYP51 genes of the mutants, which resulted in two substitutions (I281T, and T314A) in the predicted sequence of the FgCYP51A subunit, as well as seven (S195F, Q332V, V333L, L334G, M399T, E507G, and E267G) in the FgCYP51C subunit. In addition, it was also noted that the expression of the CYP51 genes in one of the mutants, which lacked point mutations, was significantly up-regulated in response to tebuconazole treatment. Conclusions: These results provide useful data that allow for more rational use of tebuconazole in the control of F. graminearum, as well as for more effective monitoring of fungicide resistance in the field. [ABSTRACT FROM AUTHOR]

Blueberry is an important perennial fruit crop with expanding consumption and production worldwide. Consumer demand for blueberries has grown due to the desirable flavor and numerous health benefits, and fresh market production in the U.S. has risen in turn. U.S. imports have also increased to satisfy year-round consumer demand for fresh blueberries. Pre- and post-harvest fruit diseases such as anthracnose (caused by Colletotrichum spp.) and botrytis fruit rot (caused by Botrytis spp.) have a significant impact on fruit quality and consumer acceptance. These are also among the most difficult diseases to control in the blueberry cropping system. These latent pathogens can cause significant losses both in the field, and especially during transport and marketplace storage. Although both diseases result in rotted fruit, the biology and infection strategies of the causal pathogens are very different, and the management strategies differ. Innovations for management, such as improved molecular detection assays for fungicide resistance, postharvest imaging, breeding resistant cultivars, and biopesticides have been developed for improved fruit quality. Development and integration of new strategies is critical for the long-term success of the blueberry industry. [ABSTRACT FROM AUTHOR]

Fusarium root rot caused by the Fusarium species complex significantly affects the yield and quality of Angelica sinensis, a valuable medicinal herb. Traditional management primarily relies on chemical fungicides, which have led to pathogen resistance, environmental hazards, and concerns regarding public health and the active components in A. sinensis. This study explores the efficacy of a novel plant-derived biopesticide Shi Chuang Zhi Feng Ning (T1; SCZFN), alongside Bacillus subtilis wettable powder (T2) and a chemical fungicide (T3), in controlling root rot and understanding their impacts on the rhizosphere microbial community and root metabolome. Results of the field experiment demonstrated that treatments T1 and T3 achieved control efficiencies of 73.17% and 75.45%, respectively, significantly outperforming T2 (39.99%) and the control. High-throughput sequencing revealed that all treatments altered the diversity and structure of microbial communities, with T1 and T2 reducing the abundance of taxa linked to root rot, such as Muribaculaceae spp., Humicola spp., Fusarium spp., and Mycochlamys spp. Treatment T1 notably enhanced beneficial bacterial taxa, including Acidobacteria spp., Nitrospira spp., and Pedosphaeraceae spp., involved in carbon cycling and plant growth promotion. Metabolomic analysis identified 39, 105, and 45 differentially expressed metabolites (DEMs) across the treatments, demonstrating T1's potential to modulate the root metabolome effectively. Further, a correlation analysis demonstrated a stronger correlation between distinct microorganisms with significant influence and DEMs of T1 treatment compared to other treatments. These findings underscore biopesticide SCZFN's role in enhancing plant health and disease suppression in A. sinensis, providing insights into its biocontrol mechanisms and supporting the development of sustainable disease management strategies in its cultivation. [ABSTRACT FROM AUTHOR]

Gray mold, caused by Botrytis sp., is a significant disease in Colombian rose crops and its control depends primarily on the intensive use of chemically synthesized fungicides. Despite the importance of this pathogen, there is limited information in Colombian floriculture about molecular taxonomy of species, fungicide resistance of populations and their genetic mechanism of resistance. In this study, we analyze 12 isolates of this fungus collected from rose-producing crops in the Department of Cundinamarca and conducted phylogenetic analysis using HSP60, G3PDH, and RPB2 gene sequences. Additionally, we realize phenotypic and genotypic characterization of resistance to the fungicides fenhexamid, carboxin, and prochloraz, evaluating the in vitro EC50 and presence of mutations of target genes of each isolate. All isolates were characterized as Botrytis cinerea in the phylogenetic analysis and presents different levels of resistance to each fungicide. These levels are related to mutations in target genes, with predominancy of L195F and L400F in the ERG27 gene to fenhexamid resistance, H272R/Y in the SDHB gene for carboxin resistance, and Y136F in the CYP51 gene for prochloraz resistance. Finally, these mutations were not related to morphological changes. Collectively, this knowledge, presented for the first time to the Colombian floriculture, contribute to a better understanding of the genetic diversity and population of B. cinerea from rose-producing crops in the department of Cundinamarca, and serve as a valuable tool for making informed decisions regarding disease management, future research, and improving crop management and sustainability in the Colombian floriculture industry. [ABSTRACT FROM AUTHOR]

Botrytis blossom blight and fruit rot, caused by Botrytis cinerea, is a significant threat to blueberries, potentially resulting in substantial economic losses if not effectively managed. Despite the recommendation of various cultural and chemical practices to control this pathogen, there are widespread reports of fungicide resistance, leading to decreased efficacy. This study aimed to characterize the resistance profile of B. cinerea isolated from blighted blossoms and fruit in 2019, 2020 and 2022 (n = 131, 40, and 37 for the respective years). Eight fungicides (fludioxonil, thiabendazole, pyraclostrobin, boscalid, fluopyram, fenhexamid, iprodione, and cyprodinil) were tested using conidial germination at specific discriminatory doses. Additionally, 86 isolates were phylogenetically characterized using the internal transcribed spacer regions (ITS) and the protein coding genes: glyceraldehyde-3-phosphate dehydrogenase (G3PDH), heatshock protein 60 (HSP60), and RNA polymerase II second largest subunit (RPB2). This revealed higher fungicide resistance frequencies in 2020 and 2022 compared to 2019. Over all 3 years, over 80% of the isolates were sensitive to fludioxonil, fluopyram, and fenhexamid. Pyraclostrobin and boscalid showed the lowest sensitivity frequencies (<50%). While multi-fungicide resistance was observed in all the years, none of the isolates demonstrated simultaneous resistance to all tested fungicides. Botrytis cinerea was the most prevalent species among the isolates (74) with intraspecific diversity detected by the genes. Two isolates were found to be closely related to B. fabiopsis, B. galanthina, and B. caroliniana and 10 isolates appeared to be an undescribed species. This study reports the discovery of a potentially new species sympatric with B. cinerea on blueberries in Michigan. [ABSTRACT FROM AUTHOR]

Ramularia leaf spot of barley, caused by Ramularia collo-cygni has become a serious disease threat to barley production. By inducing necrotic lesions, the disease expiates the onset of leaf senescence, which can result in significant grain yield and quality losses. In addition to surviving between seasons in trash, stubble and volunteers, R. collo-cygni can be transmitted from seed to emerging seedlings. As a potential additional means of transmission it may also pose a risk for the spread of specific traits such as fungicide resistance. In the present study, we screened Irish barley seed stocks harvested in the years 2015–2017 for the presence of R. collo-cygni using qPCR, and subsequently using an amplicon sequencing assay screened for the presence of alleles in the SDHC gene of R. collo-cygni associated with SDHI resistance. Over the three year period > 60% of the samples screened had detectable levels of R. collo-cygni present. In a subsample of these five alleles associated with resistance (SDHC—N87S, G91R, H145R, R152M and H153R) were detected. The prevalence of the key alleles C-N87S and C-H146R remained stable over the three year period, and was similar to that detected amongst an isolate collection established in 2022. [ABSTRACT FROM AUTHOR]

Fungicide resistance to crop protection products is a critical sustainability issue in modern agriculture that requires constant monitoring of the field situation considering different environmental conditions and agricultural practices. Regulation strategies based on resistance risk ranking of both pathogen and active compound, underpinned by fast and broad field monitoring, shall result in recommendations for suitable practices with the aim to stabilize or even to restore the sensitivity situation. Alternating and mixing various products according to their modes of action belong to the most common and the most efficient mitigation methods. Though, these resistance management measures can be implemented best when precise knowledge of both the molecular target and the cell biology of the pathogen as well as of the resistance mechanism is acknowledged. To this end, we have investigated the molecular target and cellular effects of fluopicolide, one of the most effective Oomyceticides in the market. By combining data of genomic analysis of resistant field isolates of Plasmopara viticola and Phytophthora infestans with UV-mutagenized strains of P. infestans, we identified the enzyme vacuolar H+-ATPase as the target protein. Biochemical assays confirmed that fluopicolide inhibits specifically Oomycetes targets and has no residual activity on true fungi or insect orthologs. [ABSTRACT FROM AUTHOR]

Molecular methods are one of the most effective tools to monitor fungicide resistance. Long-read sequencing is an emerging technology in the field of plant pathology. We developed a PCR-based Oxford Nanopore Technologies amplicon sequencing method allowing the simultaneous detection and quantification of Plasmopara viticola variants conferring fungicide resistance to complex III inhibitors, zoxamide and oxathiapiprolin in the same vineyard population. Analysis of cyt b gene variants in natural P. viticola populations showed that almost all samples (23 out of 24 populations) collected in France contain variants G143A, S34L and/or E203-DE-V204 insertion. In the analysed populations, only cyt b reads with both substitutions S34L and G134A were detected at significant levels, suggesting the selection of resistant strains to both QoI fungicides and ametoctradin. French P. viticola population P36 with low sensitivity to oxathiapiprolin did not contain oxysterol binding protein sequences with both variants G770V and N837I, suggesting the presence of two different genotypes of P. viticola strain in this population. Zoxamide insensitivity associated with β-tubulin variants carrying the C239S substitution was detected in Italian vineyard populations but not in France. [ABSTRACT FROM AUTHOR]

Plant pathogens are highly adaptable, and have evolved to overcome control measures including multiple classes of fungicides. More effective management requires a thorough understanding of the evolutionary drivers leading to resistance. Experimental evolution can be used to investigate evolutionary processes over a compressed timescale. For fungicide resistance, applications include predicting resistance ahead of its emergence in the field, testing potential outcomes under multiple different fungicide usage scenarios or comparing resistance management strategies. This review considers different experimental approaches to in vitro selection, and their suitability for addressing different questions relating to fungicide resistance. When aiming to predict the evolution of new variants, mutational supply is especially important. When assessing the relative fitness of different variants under fungicide selection, growth conditions such as temperature may affect the results as well as fungicide choice and dose. Other considerations include population size, transfer interval, competition between genotypes and pathogen reproductive mode. However, resistance evolution in field populations has proven to be less repeatable for some fungicide classes than others. Therefore, even with optimal experimental design, in some cases the most accurate prediction from experimental evolution may be that the exact evolutionary trajectory of resistance will be unpredictable. [ABSTRACT FROM AUTHOR]

Plasmopara viticola is controlled by fungicides with different modes of action, which include zoxamide. Zoxamide was developed in 1998 by Dow AgroSciences LIC (Indianapolis, IN) and has been commercialized since 2001 by Rohm and Haas Company. This fungicide is highly effective against oomycetes, used for foliar application in vine crops, potato, and other vegetables to control oomycete-induced diseases. Zoxamide acts by causing mitotic arrest by binding to β-tubulin, inhibiting tubulin polymerization and cell division of the pathogen. In the past three decades, the management of fungicide resistance has emerged as a significant concern for both growers and regulatory authorities; this is primarily due to the substantial increase in resistance, in terms of occurrence and spread, towards most fungicide groups. The monitoring of the effectiveness of fungicides is the only way to accurately identify as soon as possible the onset of resistance. In this study, we were interested in tracking the changes in the sensitivity of zoxamide to P. viticola populations collected during a 6-year monitoring (2017–2022) in two Italian locations: the autonomous province of Trento and the autonomous region of Friuli-Venezia Giulia. Bioassays on leaf discs were carried out, and EC50 and MIC values were elaborated. From our results, zoxamide showed for a long period of time high sensitivity, but over the last years we observed a change, as in 2022 most of the samples tested in these two regions showed MIC > 100 mg L−1. [ABSTRACT FROM AUTHOR]

The management of Asian soybean rust (ASR) involves a combination of cultural and chemical strategies. Phakopsora pachyrhizi-resistant isolates to fungicides have emerged, harboring point mutations in the CYP51, CYTB, and SDH genes. These mutants have advantages in regions extensively utilizing site-specific fungicides. However, the dynamics of selection within a single season remain poorly understood. Thus, this study aimed to investigate the potential selection of mutants following four fungicide applications of commercial mixtures (DMI, QoI, and SDHI), in contrast to untreated control plots. Disease progression and fungicide efficacy were also assessed. In the regions of Arapoti, Castro, Ponta Grossa in Paraná, and Itaberá in São Paulo, mutations on SDH, CYTB, and CYP51 genes were identified, leading to reduced sensitivity to SDHI, QoI, and DMI fungicides. F120L + Y131H mutations in the CYP51 gene were found in Arapoti and Ponta Grossa, and Y131F + K142R + I147T mutations in the CYP51 gene were identified in Itabera-SP. Population from Arapoti had the F129L mutation in the CYTB gene, with a high frequency (> 80%) in treated and untreated plots in Castro and Ponta Grossa. The C-I86F mutation in the SDH gene was detected in all municipalities, exhibiting statistical significance in Arapoti-PR compared to unthread control. In Itaberá, Arapoti, and Ponta Grossa disease severity reached 80% in untreated controls, while fungicides demonstrated efficacies of ranging from 50 to 90%. Importantly, all detected mutations were less frequent in untreated controls, underscoring the significance of anti-resistance management strategies. [ABSTRACT FROM AUTHOR]

The aim of the study was to provide information on the fungicide sensitivity of grape powdery mildew (Erysiphe necator) to some of the modes of action used for grape powdery mildew control with a focus on Europe. QoIs: most samples analysed in this study showed high values of the G143A mutation, which leads to low field performance of QoIs. Therefore, QoIs have lost their strength on grape powdery mildew control. DMIs: European wide sensitivity studies indicated that DMIs are only slightly and differently affected by the mutation Y136F, being frequently detected in the pathogens' cyp51 gene. Mefentrifluconazole was recently developed for grape powdery mildew control, and its sensitivity is even not affected by this mutation. APKs: resistance towards aryl-phenyl-ketones (APKs) has also been reported in various regions in Europe, and monitoring studies showed a heterogenous distribution from a sensitive situation towards populations with higher APK resistance. SDHIs: adaptation of Erysiphe necator to succinate dehydrogenase inhibitors (SDHI) is more recent and quite complex because different mutations can be found in the B and C-subunits of the SDH gene which have different effects on SDHIs. Different mutation pattern in different geographical regions have been found which could be the result of different SDHI use. Therefore, the implementation of resistance management strategies, including the use of various modes of action in alternation and mixture, are recommended for a sustainable disease management in grapes. [ABSTRACT FROM AUTHOR]

Picarbutrazox is the active ingredient of Vayantis®, a novel seed treatment fungicide developed by Syngenta and discovered by Nippon Soda. Vayantis® received registration from the US EPA in 2021. Picarbutrazox is a systemic fungicide and belongs to the tetrazolyloximes chemical group of fungicides, and its mode of action is still unknown (FRAC group U17). Picarbutrazox targets oomycete plant pathogens and controls diseases caused by Pythium, Phytophthora, and downy mildews. Picarbutrazox is in a new mode-of-action group with no known cross-resistance to other oomycete compounds. The sensitivity to Picarbutrazox of 528 isolates belonging to 40 different Pythium species was determined in vitro. Pythium isolates were collected from infected plants including corn, soybean, cotton, and other crops from 17 different states. Pythium isolates were also obtained from collections kept at universities. Isolates were identified at the species level using morphological and molecular tools. Mycelial growth inhibition was quantified using the following Picarbutrazox concentrations: 0, 0.00001, 0.0001, 0.001, 0.01, and 0.1 mg/L. All the species of Pythium tested were sensitive to Picarbutrazox. The sensitivity distribution (EC50 values) across all the Pythium species tested had a mean sensitivity of 0.000376 mg ai/L. The Picarbutrazox sensitivity of 40 species of Pythium species has been documented, and results demonstrate the high in vitro intrinsic activity of this fungicide to control Pythium species. The high potency of Picarbutrazox to control Pythium diseases in corn, soybeans, cotton, and other crops has also been demonstrated under field conditions when used as a seed treatment. Picarbutrazox, with its novel mode of action, will contribute to the management of potential fungicide resistance issues developed by other fungicide products controlling Pythium, including mefenoxam and ethaboxam. [ABSTRACT FROM AUTHOR]

This document provides an update on target site mutations associated with resistance to fungicides. It introduces a method of labeling homologous mutations based on alignment to an archetype sequence to avoid confusion caused by differing gene lengths in different pathogen species. The document includes three tables that provide detailed information on substitutions in archetype genes and their homologous positions in other species. These tables can be useful for researchers studying these proteins in various species. The document acknowledges the support of the Australian Grains Research and Development Corporation and Curtin University, with funding provided by GRDC. The authors of the document are Richard Oliver, James Hane, Wesley Mair, and Fran Lopez-Ruiz. [Extracted from the article]

Efficient grapevine downy mildew control necessitates the implementation of anti-resistance strategies to ensure the ongoing efficacy of available substances and optimal disease control. With the gradual disappearance of multi-site fungicides from the market, reliance on single-site fungicides poses a long-term risk of selecting strains resistant to multiple modes of action. Challenges in disease management encompass selecting optimal spray programs and monitoring field population sensitivity. This study evaluated the efficacy of anti-resistance strategies, including two single-site fungicides (mandipropamid and oxathiapiprolin), on disease control and fungicide sensitivity through a combination of field trials and laboratory tests for the biological and molecular characterization of the pathogen populations over a three-year period (2019–2021). Mandipropamid, a cellulose synthase inhibitor, is used since a long time for downy mildew control, while oxathiapiprolin, an OxySterol Binding Protein homologue Inhibitor, was introduced recently. Field trials demonstrated effective disease control, even in the presence of mandipropamid-resistant strains (with G1105S/V mutations in PvCesA3) and revealed a pronounced selection and spread of resistance to both fungicides in the vineyard where disease pressure was higher. Characterizing pathogen strains remained a significant obstacle in sensitivity monitoring, hindering precise determination of resistance frequencies related to fungicide programs. Traditional techniques, in fact, lack the resolution required for high-throughput isolation and characterization of resistant individuals. To address this challenge, we propose utilizing flow cytometry and fluorescence-activated cell sorting on field sporangia populations, a method able to determine both the number of resistant isolates and isolate pathogen strains in a single assay. [ABSTRACT FROM AUTHOR]

The grass species, Agrostis stolonifera, is commonly used on golf course and lawn bowling greens and can experience frequent fungicide applications, which has given rise to problems with fungicide resistance in major turfgrass pathogens. There are other organisms in this environment which may be naturally tolerant to particular fungicides. This work investigated the identity and diversity of organisms isolated from A. stolonifera leaves, which presumably have had very little exposure to fungicides. Samples were collected monthly throughout two growing seasons. Over 2400 leaf blades were placed on a selective growth medium to select for propiconazole-tolerant fungi. The isolates were resolved into 19 different species using ITS DNA sequencing. The appearance of species was consistent between the two sampling seasons, with ten species in March through May, two additional species in June through July, and another seven species in September through October. The four species that showed the greatest representation among the ~ 2200 isolates were as follows: Microdochium bolleyi (23%), Rhizoctonia solani (11%), Papiliotrema flavescens (9%), and Cryptococcus aspenensis (9%). This study is the first report of Mucor nidicola, Parasarocladium breve, Trichoderma gamsii, T. caribbaeum, and Blakeslea trispora isolated from the A. stolonifera phyllosphere. Why these fungal species show tolerance toward propiconazole remains to be explored, as well as whether the genetic factors conferring resistance are the same as those that produce acquired resistance, and whether this resistance is intrinsic to these species. [ABSTRACT FROM AUTHOR]

We detected isolates with SdhC-I87F-conferring mutations that were slightly SDHI-adapted in the barley leaf rust Puccinia hordei in France and the UK in 2019. SdhC-I87F of P. hordei is orthologous to SdhC-I86F in Phakopsora pachyrhizi, and SdhC-I88F in Puccinia horiana induced SDHI resistance. Nevertheless, the field performance of SDHIs against P. hordei was good, although strains with SdhC-I87F dominated the field. The sensitivity ranges were narrow for wheat leaf rust and Puccinia triticina in 2019; however, isolates with slightly higher EC50 values were obtained in southern France and the eastern UK in 2021. These isolates of P. triticina harbored an orthologous SdhC-I87F-conferring mutation. The range of EC50 values for the SDHI fungicide inpyrfluxam overlapped between the wild type and SdhC-I87F isolates. Further analyses are currently underway. [ABSTRACT FROM AUTHOR]

This document provides a comprehensive overview of various plant diseases and their prevalence in different crops in Canada. It includes information on diseases such as Fusarium head blight, leaf rust, stripe rust, blackleg, sclerotinia stem rot, clubroot, root rot, anthracnose, ascochyta blight, and bacterial blight in crops like wheat, canola, lentils, peas, chickpeas, and soybeans. The surveys conducted in different provinces provide data on the incidence and severity of these diseases, as well as the dominant pathogens responsible for them. This information can be valuable for researchers studying plant diseases and for farmers seeking to manage and prevent these diseases in their crops. [Extracted from the article]

Chemical control of grape black rot, caused by Phyllosticta ampelicida, relies mainly on the use of demethylation inhibitors (DMIs) and quinone outside inhibitors (QoIs). The effectiveness of QoI fungicides is influenced by alternative respiration activity, and the exon/intron structure and point mutations in the target protein's gene, the cytochrome b (cytb) gene. Our study aims to investigate the QoI fungicide sensitivity of 48 P. ampelicida isolates in vitro by measuring EC50 and the molecular characteristics of the cytb gene and its mRNA in P. ampelicida and other Phyllosticta species. Mycelial growth tests revealed that the P. ampelicida isolates were sensitive to both azoxystrobin and trifloxystrobin; baseline EC50 values were 0.029 and 0.022 μg/mL, respectively. Addition of salicylhydroxamic acid (SHAM) resulted in lower EC50 values (0.024 and 0.017 μg/mL, respectively). None of the typical point mutations conferring resistance to QoIs in some fungi were detected. A group I intron was present right after the 143rd codon in the cytb gene in four of the six Phyllosticta species examined. The sequence and exon/intron structure of the cytb gene of P. ampelicida isolated from Vitis vinifera is studied in detail and published here. Our results indicate a low risk of QoI resistance development via the G143A mutation in P. ampelicida. [ABSTRACT FROM AUTHOR]

Fungicide resistance is often conferred through the mutation of genes encoding fungicide targets or proteins that remove fungicides from cells, but mechanisms can vary widely between taxa. Discovering the specific resistance alleles present in pathogen populations is essential for monitoring the evolution and movement of resistant genotypes. In this study, we explored the genomic basis of demethylase inhibitor (DMI) resistance in Leptosphaeria maculans, the main pathogen of the canola crop Brassica napus. Using an international collection of over 200 genome‐sequenced isolates, we assayed in vitro sensitivity to the DMI tebuconazole and conducted a genome‐wide association study on a variant set including single‐nucleotide polymorphisms (SNPs), small indels and structural variants. The main resistance allele identified was a 237 bp remnant transposable element insertion in the promoter of the erg11/CYP51 DMI target gene in a large proportion of isolates from Europe, an allele known to confer DMI resistance in Australia. Several associated loci were identified, none of which are commonly linked to DMI resistance in other phytopathogens. We also found little to no relationship between DMI tolerance and baseline growth rate, suggesting minimal fitness effects of fungicide resistance in these isolates. This study indicates common DMI resistance alleles in L. maculans are shared across continents and erg11/CYP51 coding mutations, which are near‐ubiquitous in other fungal pathogens, may not underpin DMI resistance in this species. Furthermore, that resistance occurs frequently in numerous canola‐growing regions suggests management is essential for growers. [ABSTRACT FROM AUTHOR]

The use of plant genetic resources (PGR)—wild relatives, landraces, and isolated breeding gene pools—has had substantial impacts on wheat breeding for resistance to biotic and abiotic stresses, while increasing nutritional value, end‐use quality, and grain yield. In the Global South, post‐Green Revolution genetic yield gains are generally achieved with minimal additional inputs. As a result, production has increased, and millions of hectares of natural ecosystems have been spared. Without PGR‐derived disease resistance, fungicide use would have easily doubled, massively increasing selection pressure for fungicide resistance. It is estimated that in wheat, a billion liters of fungicide application have been avoided just since 2000. This review presents examples of successful use of PGR including the relentless battle against wheat rust epidemics/pandemics, defending against diseases that jump species barriers like blast, biofortification giving nutrient‐dense varieties and the use of novel genetic variation for improving polygenic traits like climate resilience. Crop breeding genepools urgently need to be diversified to increase yields across a range of environments (>200 Mha globally), under less predictable weather and biotic stress pressure, while increasing input use efficiency. Given that the ~0.8 m PGR in wheat collections worldwide are relatively untapped and massive impacts of the tiny fraction studied, larger scale screenings and introgression promise solutions to emerging challenges, facilitated by advanced phenomic and genomic tools. The first translocations in wheat to modify rhizosphere microbiome interaction (reducing biological nitrification, reducing greenhouse gases, and increasing nitrogen use efficiency) is a landmark proof of concept. Phenomics and next‐generation sequencing have already elucidated exotic haplotypes associated with biotic and complex abiotic traits now mainstreamed in breeding. Big data from decades of global yield trials can elucidate the benefits of PGR across environments. This kind of impact cannot be achieved without widescale sharing of germplasm and other breeding technologies through networks and public–private partnerships in a pre‐competitive space. [ABSTRACT FROM AUTHOR]

BACKGROUND: Grapevine downy mildew, caused by Plasmopara viticola, is an economically important disease in Australia and worldwide. The application of fungicides is the main tool to control this disease. Frequent fungicide applications can lead to the selection of resistant P. viticola populations, which has negative impacts on the management of the disease. Identification of resistance and its prevalence is necessary to inform resistance management strategies. RESULTS: A total of 86 P. viticola isolates were collected between 2017 and 2022 from vineyards in 15 growing regions across Australia for four fungicide groups; phenylamide (PA, group 4), carboxylic acid amide (CAA, group 40), quinone outside inhibitor (QoI, group 11) and quinone outside inhibitor stigmatellin binding type (QoSI, group 45). Decreased phenotypic sensitivity was detected for all four groups, and resistance to metalaxyl‐M (PA) and pyraclostrobin (QoI), was detected. Genetic analysis to detect the G143A (QoI) and G1105S (CAA) mutations using amplicon‐based sequencing was performed for 239 and 65 isolates collected in 2014–2017 and 2017–2022, respectively. G143A was detected in 8% and 52% of isolates, respectively, with strong association to phenotypic resistance. However, G1105S was not detected in any isolates. CONCLUSION: Plasmopara viticola isolates in Australia with resistance to at least two fungicide groups have been detected, therefore it is necessary to adopt resistance management strategies where resistance has been detected. Vineyards should continue to be monitored to improve management strategies for downy mildew. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Garlic is one of the most popular spices in the world and the second most widely cultivated Allium species next to the onion. Garlic production is reduced due to many biotic and abiotic factors, among which white rot disease caused by Stromatinia cepivora (Berk.) Whetzel causes severe yield losses. The study was conducted to evaluate the combined effects of chemical fungicides and garlic varieties on the epidemic development of white rot disease. The experiment was conducted at Chefanen Kebele using three garlic varieties and three chemicals during the 2019 and 2020 seasons. The experimental design was a randomized complete block with three replicates. The application of Apron Star 42, a commercial fungicide containing Thiametoxam 20%, Metalaxyl-M 20% and Difenconazole 2%, significantly reduced the white rot disease on all varieties as compared to the untreated local variety. Bishoftu Nech and MM-98 varieties exhibited fast emergence as compared to the local variety, consequently increasing the yield and yield components of garlic. The application of Apron Star 42, significantly increased yield parameters compared to the untreated control. The significant effect and the negative correlations of days to maturity, growth parameters, yield, and yield components with disease parameters indicated that the white rot disease had a very crucial impact on garlic yield. Application of Apron Star 42 to improved garlic varieties is recommended to reduce the severity of white rot infections and to increase garlic production in the study area. [ABSTRACT FROM AUTHOR]

BACKGROUND: Peach brown rot caused by Monilinia fructicola severely affects the quality and yield of peach, resulting in large economic losses worldwide. Methyl benzimidazole carbamate (MBC) fungicides and sterol demethylation inhibitor (DMI) fungicides are among the most applied chemical classes used to control the disease but resistance in the target pathogen has made them risky choices. Timely monitoring of resistance to these fungicides in orchards could prevent control failure in practice. RESULTS: In the current study, we developed methods based on recombinase polymerase amplification (RPA) and CRISPR/Cas12a systems to detect MBC and DMI resistance based on the E198A mutation in the β‐tubulin (MfTub2) gene and the presence of the Mona element in the upstream region of the MfCYP51, respectively. For MBC resistance, RPA primers were designed that artificially incorporated PAM sites to facilitate the CRISPR/Cas12a reaction. Subsequently, specific tcrRNAs were designed based on the E198A mutation site. For the detection of the Mona element, we designed RPA primers M‐DMI‐F2/M‐DMI‐R1 that in combination with crRNA1 detected 'Mona' and distinguished resistant from sensitive strains. CONCLUSION: Both methods exhibited high sensitivity and specificity, requiring only a simple isothermal device to obtain results within 1 h at 37 °C. The FQ‐reporter enabled visualization with a handheld UV or white light flashlight. This method was successfully used with purified DNA from lab cultures and crude DNA from symptomatic fruit tissue, highlighting its potential for on‐site detection of resistant strains in orchards. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

ABSTRACT The plant hormone jasmonate (JA) regulates plant growth and immunity by orchestrating a genome‐wide transcriptional reprogramming. In the resting stage, JASMONATE‐ZIM DOMAIN (JAZ) proteins act as main repressors to regulate the expression of JA‐responsive genes in the JA signaling pathway. However, the mechanisms underlying de‐repression of JA‐responsive genes in response to JA treatment remain elusive. Here, we report two nuclear factor Y transcription factors NF‐YB2 and NF‐YB3 (thereafter YB2 and YB3) play key roles in such de‐repression in Arabidopsis. YB2 and YB3 function redundantly and positively regulate plant resistance against the necrotrophic pathogen Botrytis cinerea, which are specially required for transcriptional activation of a set of JA‐responsive genes following inoculation. Furthermore, YB2 and YB3 modulated their expression through direct occupancy and interaction with histone demethylase Ref6 to remove repressive histone modifications. Moreover, YB2 and YB3 physically interacted with JAZ repressors and negatively modulated their abundance, which in turn attenuated the inhibition of JAZ proteins on the transcription of JA‐responsive genes, thereby activating JA response and promoting disease resistance. Overall, our study reveals the positive regulators of YB2 and YB3 in JA signaling by positively regulating transcription of JA‐responsive genes and negatively modulating the abundance of JAZ proteins. [ABSTRACT FROM AUTHOR]

Bakanae disease is mainly caused by Fusarium fujikuroi and is a significant fungal disease with a number of disastrous consequences. It causes great losses in rice production. However, few studies have focused on the details of bakanae disease resistance in rice. Here, we summarize and discuss the progress of bakanae disease resistance in rice. Besides rice germplasm screening and resistance-related gene/quantitative trait locus (QTL) exploration, the route of pathogen invasion in rice plants was determined. We further discussed the regulation of phytohormone-related genes and changes in endogenous phytohormones in rice plants that are induced by the pathogen. To achieve better control of bakanae disease, the use of natural fungicides was assessed in this review. During rice—F. fujikuroi interactions, the infection processes and spatial distribution of F. fujikuroi in infected seedlings and adult plants exhibit different trends. Fungal growth normally occurs both in resistant and susceptible cultivars, with less abundance in the former. Generally, bakanae disease is seed-borne, and seed disinfection using effective fungicides should always be the first and main option to better control the disease. Besides the friendly and effective measure of using natural fungicides, breeding and utilization of resistant rice cultivars is also an effective control method. To some extent, rice cultivars with low grain quality, indica subspecies, and some dwarf or semi-dwarf rice germplasms are more resistant to bakanae disease. Although no highly resistant germplasms were obtained, 37 QTLs were located, with almost half of the QTLs being located on chromosome 1. Using omics methods, WRKYs and MAPKs were usually found to be regulated during rice—F. fujikuroi interactions. The regulation of certain phytohormone-related genes and changes in some endogenous phytohormones induced by the pathogen were clear, i.e., it downregulated gibberellin-related genes and repressed endogenous gibberellins in resistant genotypes, but the opposite results were noted in susceptible rice genotypes. Overall, exploring resistant germplasms or resistance-related genes/QTLs for the breeding of rice with bakanae disease resistance, expanding research on the complex mechanism of rice—F. fujikuroi interactions, and using cost-effective and eco-friendly innovative control methods against the disease are necessary for present and future bakanae disease management. [ABSTRACT FROM AUTHOR]

We evaluated the effects of fungicides on strawberry powdery mildew (PM) fungus, Podosphaera aphanis, using an electrostatic technique. Thirty-six fungicides were sprayed on single colonies of P. aphanis on leaves of strawberry seedlings (Fragaria × ananassa Duchesne ex Rozier). Colony development varied depending on the tested fungicides. Particularly, pyraziflumid, triflumizole, triforine, polyoxin, sodium hydrogen carbonate + copper wettable powder, and flutianil + mepanipyrim were highly effective for reducing colony development. P. aphanis colonies were histochemically stained to observe the morphological characteristics of fungal cells forming normal and abnormal conidiophores. Abnormal conidiophores were classified into seven types based on their morphological and cytological characteristics. Finally, asexual conidia were collected from single P. aphanis colonies on the leaves spray-treated with fungicides using a dielectrically polarized insulator plate (electrostatic spore collector); conidia attracted to the insulator plates were counted using a high-fidelity digital microscope. Most tested fungicides highly inhibited the production and/or germination of asexual conidia. The germination of asexual conidia was observed only in thiophanate-methyl (methyl benzimidazole carbamates fungicides; MBC fungicides) and azoxystrobin (quinone outside inhibitors; QoI fungicides). Assessing with the electrostatic technique, we clarified that P. aphanis has developed resistance to both thiophanate-methyl and azoxystrobin. Thus, the methodological assessment analyzing the colony development and the number of conidia released from single colonies will be helpful information for screening effective fungicides. [ABSTRACT FROM AUTHOR]

In this paper, an extensive review of the literature is provided examining the significance of tolerance to fungal diseases in wheat amidst the escalating global demand for wheat and threats from environmental shifts and pathogen movements. The current comprehensive reliance on agrochemicals for disease management poses risks to food safety and the environment, exacerbated by the emergence of fungicide resistance. While resistance traits in wheat can offer some protection, these traits do not guarantee the complete absence of losses during periods of vigorous or moderate disease development. Furthermore, the introduction of individual resistance genes into wheat monoculture exerts selection pressure on pathogen populations. These disadvantages can be addressed or at least mitigated with the cultivation of tolerant varieties of wheat. Research in this area has shown that certain wheat varieties, susceptible to severe infectious diseases, are still capable of achieving high yields. Through the analysis of the existing literature, this paper explores the manifestations and quantification of tolerance in wheat, discussing its implications for integrated disease management and breeding strategies. Additionally, this paper addresses the ecological and evolutionary aspects of tolerance in the pathogen–plant host system, emphasizing its potential to enhance wheat productivity and sustainability. [ABSTRACT FROM AUTHOR]

Spot form net blotch, caused by Pyrenophora teres f. maculata, is a significant necrotrophic disease of barley that spread worldwide in the twentieth century. Genetic relationships were analyzed to determine the diversity, survival, and dispersal of a diverse collection of 346 isolates from Australia, Southern Africa, North America, Asia Minor, and Europe. The results, based on genome-wide DArTseq data, indicated that isolates from Turkey were lhe most differentiated with regional substructuring, together with individuals closely related to geographically distant genotypes. Elsewhere, population subdivision related to country of origin was evident, although low levels of admixturing was found that may represent rare genotypes or migration from unsampled populations. Canadian isolates were the next most diverged, and Australian and South African the most closely related. With the exception of Turkish isolates, multiple independent CypSIA mutation events (which confer insensitivity to demethylation inhibitor fungicides) between countries and within regions was evident, with strong selection for a transposable element insertion at the 3' end of lhe promoter and counterselection elsewhere. Individuals from Western Australia shared genomic regions and CypSIA haplotypes with South African isolates, suggesting a recent common origin. [ABSTRACT FROM AUTHOR]

By screening the compounding combination of Wuyiencin and chemical agents, this study aims to delay the emergence of chemical agent resistance, and provide a technical reference for scientific and rational fungicides technology. This study investigated the impacts of the antibiotic wuyiencin derived from Streptomyces albulus var. wuyiensis and its combination with pyrimethanil on the inhibition of Botrytis cinerea. Treatment with wuyiencin (≥80 µg mL−1) strongly inhibited the pathogenicity of B. cinerea and activated the plant defense response against B. cinerea. Application of 80–100 µg mL−1 wuyiencin effectively controlled grape gray mold (by 57.6–88.1% on leaves and 46.7–96.6% on fruits). Consequently, the application of 80–100 µg mL−1 wuyiencin effectively mitigated grape gray mold incidence, leading to a substantial reduction in disease symptoms to nearly imperceptible levels. When wuyiencin (at the median effective concentration [EC50]) was combined with pyrimethanil (EC50) at a ratio of 7:3, it exhibited the highest efficacy in inhibiting B. cinerea growth. This combination was significantly more potent (p < 0.05) than using wuyiencin or pyrimethanil alone in controlling gray mold on grape leaves and fruits. Furthermore, the combination effectively delayed resistance development in gray mold. The experimental results show that wuyiencin can delay resistance development by affecting the expression of methionine biosynthesis genes and reducing the activity of the cell wall-degrading enzyme activity. [ABSTRACT FROM AUTHOR]

Copyright of Jurnal Fitopatologi Indonesia is the property of IPB University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractFusarium graminearum is the most important pathogen of maize and winter wheat in Canada, resulting in yield loss and mycotoxin contamination. Fungicides are essential to manage F. graminearum in cereal crops. Until pydiflumetofen became commercial, the only available fungicides were triazoles, limiting the potential to manage fungicide resistance. Fusarium graminearum isolates were surveyed from wheat, grain maize and overwintering maize stalks in southern Ontario. Chemotype and the baseline sensitivity to pydiflumetofen were determined in addition to sensitivity to common fungicides used to control F. graminearum. Fusarium graminearum has several strains producing different trichothecenes called chemotypes. In Ontario, 73.3% of the F. graminearum isolates were 3ANX chemotypes producing 7α-hydroxy, 15-deacetylcalonectrin, in addition to 15-acetyldeoxynivalenol and deoxynivalenol; the remaining isolates were 15ADON chemotypes producing only 15-acetyldeoxynivalenol and deoxynivalenol. Chemotype was not affected by isolate source (wheat grain, maize grain, maize stalks) nor by location. All isolates were sensitive to pydiflumetofen and fungicide products containing pydiflumetofen. The mean EC50 for isolates exposed to pydiflumetofen was 0.05 µg mL−1 (range 0.01–0.10 µg mL−1). The mean EC50 for isolates exposed to Miravis®Ace (containing pydiflumetofen and propiconazole), Miravis®Neo 300SE (containing pydiflumetofen, azoxystrobin and propiconazole), Caramba® (containing metconazole), Proline® (containing prothioconazole) and Prosaro (containing prothioconazole and tebuconazole) was 0.06, 0.13, 0.18, 0.05, 3.75 and 0.30 µg mL−1, respectively. These data will be useful in monitoring the development of fungicide resistance. [ABSTRACT FROM AUTHOR]

Sirtuins (SRTs) are a group of nicotinamide adenine dinucleotide (NAD+)‐dependent deacetylase that target both histone and nonhistone proteins. The biological function of SRT in horticultural plants has been rarely studied. In this study, FaSRT1‐2 was identified as a key member of the 8 FaSRTs encoded in cultivated strawberry genome. Transient overexpression of FaSRT1‐2 in strawberry fruit accelerated ripening, increased the content of anthocyanins and sugars, enhanced ripening‐related gene expression. Moreover, stable transformation of FaSRT1‐2 in strawberry plants resulted in enhanced vegetative growth, increased sensitivity to heat stress and increased susceptibility to Botrytis cinerea infection. Interestingly, knocking out the homologous gene in woodland strawberry had the opposite effects. Additionally, we found the content of stress‐related hormone abscisic acid (ABA) was decreased, while the growth‐related gibberellin (GA) concentration was increased in FaSRT1‐2 overexpression lines. Gene expression analysis revealed induction of heat shock proteins, transcription factors, stress‐related and antioxidant genes in the FaSRT1‐2‐overexpressed plants while knocked‐out of the gene had the opposite impact. In conclusion, our findings demonstrated that FaSRT1‐2 could positively promote strawberry plant vegetative growth and fruit ripening by affecting ABA and GA pathways. However, it negatively regulates the resistance to heat stress and B. cinerea infection by influencing the related gene expression. Summary statement: FaSRT1‐2 is likely to exert a positive regulatory effect on both strawberry fruit ripening and vegetative growth by stimulating sugar, anthocyanin, and the gibberellin metabolism pathway. Moreover, FaSRT1‐2 appears to enhance the susceptibility of strawberry plants to heat stress while also promoting defence against Botrytis cinerea through alterations in abscisic acid metabolism and stress‐related genes expression. [ABSTRACT FROM AUTHOR]

Mexico generates specific phytosanitary regulations for each product and origin to prevent the entry of quarantine pests and/or delay their spread within the national territory, including fungi and oomycetes. Phytosanitary regulations are established based on available information on the presence or absence of these pathogens in the country; however, the compilation and precise analysis of reports is a challenging task due to many publications lacking scientific rigor in determining the presence of a taxon of phytosanitary interest in the country. This review evaluated various studies reporting the presence of plant pathogenic fungi and oomycetes in Mexico and concluded that some lists of diseases and phytopathogenic organisms lack technical-scientific basis. Thus, it highlights the need and presents an excellent opportunity to establish a National Collection of Fungal Cultures and a National Herbarium for obligate parasites, as well as to generate a National Database of Phytopathogenic Fungi and Oomycetes present in Mexico, supported by the combination of morphological, molecular, epidemiological, pathogenicity, symptom, and micrograph data. If realized, this would have a direct impact on many future applications related to various topics, including quarantines, risk analysis, biodiversity studies, and monitoring of fungicide resistance, among others. [ABSTRACT FROM AUTHOR]

Leaves of Welsh onion (Allium fistulosum) are subject to various fungal diseases such as anthracnose (Colletotrichum species) and Stemphylium leaf blight (Stemphylium vesicarium). These diseases are the main biotic limitations to Welsh onion production in northern Taiwan. From 2018 to 2020, anthracnose symptoms were observed throughout Welsh onion fields in northern Taiwan, mainly the Sanxing area. In total, 33 strains of Colletotrichum species were isolated from diseased leaves, and major causative agents were identified based on a multilocus phylogenetic analysis using four genomic regions (act, tub2, gapdh, and internal transcribed spacer). Based on this phylogeny, Colletotrichum species causing anthracnose of Welsh onion were identified as C. spaethianum (C. spaethianum species complex) and C. circinans (C. dematium species complex) in the Sanxing area, northern Taiwan. To determine and compare the pathogenicity of each species, representative fungal strains of each species were inoculated on the cultivar 'Siao-Lyu' by spraying spore suspension onto the leaf surface. Welsh onion plants were susceptible to both species, but disease incidence and severity were higher in C. spaethianum. In total, 31 fungicides were tested to determine their efficacy in reducing mycelial growth and conidial germination of representative strains of C. spaethianum and C. circinans under laboratory conditions. Five fungicides--fluazinam, metiram, mancozeb, thiram, and dithianon--effectively reduced mycelial growth and spore germination in both C. spaethianum and C. circinans. In contrast, difenoconazole and trifloxystrobin + tebuconazole, which are commonly used in Welsh onion production in northern Taiwan, mainly the Sanxing area, were ineffective. These results serve as valuable insights for growers, enabling them to identify and address the emergence of anthracnose caused by C. spaethianum and C. circinans of Welsh onion, employing fungicides with diverse modes of action. The findings of this study support sustainable management of anthracnose in Sanxing, northern Taiwan, although further field tests of the fungicides are warranted. [ABSTRACT FROM AUTHOR]

Botrytis cinerea is a severe threat in agriculture, as it can infect over 200 different crop species with gray mold affecting food yields and quality. The conventional treatment using fungicides lead to emerging resistance over the past decades. Here, we introduce Photodynamic Inactivation (PDI) as a strategy to combat B. cinerea infections, independent of fungicide resistance. PDI uses photoactive compounds, which upon illumination create reactive oxygen species toxic for killing target organisms. This study focuses on different formulations of sodium–magnesium–chlorophyllin (Chl, food additive E140) as photoactive compound in combination with EDTA disodium salt dihydrate (Na2EDTA) as cell-wall permeabilizer and a surfactant. In an in vitro experiment, three different photosensitizers (PS) with varying Chl and Na2EDTA concentrations were tested against five B. cinerea strains with different resistance mechanisms. We showed that all B. cinerea mycelial spheres of all tested strains were eradicated with concentrations as low as 224 µM Chl and 3.076 mM Na2EDTA (LED illumination with main wavelength of 395 nm, radiant exposure 106 J cm−2). To further test PDI as a Botrytis treatment strategy in agriculture a greenhouse trial was performed on B. cinerea infected bell pepper plants (Capsicum annum L). Two different rates (560 or 1120 g Ha−1) of PS formulation (0.204 M Chl and 1.279 M Na2EDTA) and a combination of PS formulation with 0.05% of the surfactant BRIJ L4 (560 g Ha−1) were applied weekly for 4 weeks by spray application. Foliar lesions, percentage of leaves affected, percentage of leaf area diseased and AUDPC were significantly reduced, while percentage of marketable plants were increased by all treatments compared to a water treated control, however, did not statistically differ from each other. No phytotoxicity was observed in any treatment. These results add to the proposition of employing PDI with the naturally sourced PS Chl in agricultural settings aimed at controlling B. cinerea disease. This approach seems to be effective regardless of the evolving resistance mechanisms observed in response to conventional antifungal treatments. [ABSTRACT FROM AUTHOR]

BACKGROUND: Resistance to succinate dehydrogenase inhibitor (SDHI) fungicides has been reported in some rust fungi within Pucciniales. However, measuring the resistance factors conferred by a specific substitution at the target site is difficult for most species because of the difficulty in performing in vitro experiments and the complexity of the binuclear state in these obligate parasites. We focused on Puccinia horiana because it easily forms homozygous basidiospores that are sensitive to SDHIs during in vitro germination, whereas the uredospores of other rust fungi are less sensitive. RESULTS: We identified two substitutions, SdhC‐I88F and SdhD‐C125Y, that drive SDHI resistance in Pu. horiana. Using basidiospore germination inhibition tests, we measured the resistance factors for six SDHI fungicides in Pu. horiana isolates harboring SdhC‐I88F substitutions, wherein orthologous substitutions were most frequently observed in SDHI‐resistant Pucciniales, such as soybean rust (Phakopsora pachyrhizi). The resistance factors were high for penthiopyrad and benzovindiflupyr (>150), moderate for oxycarboxin and inpyrfluxam (10–30), and low for mepronil and fluxapyroxad (3–10). The most potent SDHI against SdhC‐I88F‐harboring isolates was inpyrfluxam, with a half‐maximal effective concentration (EC50) of 0.0082 mg L−1 owing to its high intrinsic activity. SdhD‐C125Y played a minor, but significant role in increasing the resistance factors (one‐ to tenfold increases), depending on the individual SDHIs. CONCLUSION: This study is the first to use basidiospore germination inhibitory tests to quantify the resistance factors for SDHI‐resistant Pucciniales. Owing to its homozygous binucleate nature and the high availability of basidiospores, Pu. horiana is useful for investigating SDHI resistance in Pucciniales. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Botrytis cinerea is one of the fungal pathogens with the widest host plant spectrum, causing serious yield losses and significant economic damage in vineyards from year to year. As an ubiquitous, polyphagous fungal pathogen, with both saprophytic and parasitic lifestyle. The sequential use of active substances belonging to the same chemical family to protect vineyards can lead to an increase in fungal chemical resistance, which is reflected in the enrichment of point mutations in the genomic regions coding proteins involved in the mechanism of action of different pesticides. The aim of our studies was to compare the sensitivity to different fungicides of B. cinerea populations in two wine regions with different pest management practices: the Tokaj region, where the presence of B. cinerea is necessary to produce noble rot wines, and the adjacent Eger Region, where a total protection against B. cinerea is desired. Our study is the first Hungarian report of some previously studied resistance mutations in ERG27 and SDHB protein-coding genes. We identified point mutations in ERG27 transmembrane domain that have not been previously described but may affect the emergence of resistance to certain fungicides. Our study shows that the B. cinerea population of the Northern Hungary region is consistently characterized by an increase in fenhexamid resistance. [ABSTRACT FROM AUTHOR]

Triazoles are widely used to control pathogenic fungi. They inhibit the ergosterol biosynthetic pathway, but the precise mechanisms leading to fungicidal activities in many fungal pathogens are poorly understood. Here, we elucidate the mode of action of epoxiconazole and metconazole in the wheat pathogen Zymoseptoria tritici and the rice blast fungus Magnaporthe oryzae. We show that both azoles have fungicidal activity and reduce fluidity, but not integrity, of the plasma membrane. This impairs localisation of Cdc15-like F-BAR proteins, resulting in defective actin ring assembly and incomplete septation. However, mutant studies and pharmacological experiments in vitro and in planta show that azole lethality is due to a combination of reactive oxygen species-induced apoptosis and macroautophagy. Simultaneous inhibition of both programmed cell death pathways abolishes azole-induced cell death. Other classes of ergosterol biosynthesis inhibitors also induce apoptosis and macroautophagy, suggesting that activation of these two cell death pathways is a hallmark of ergosterol synthesis-targeting fungicides. This knowledge will inform future crop protection strategies. Antifungal azoles inhibit ergosterol biosynthesis, but how that leads to fungistatic or fungicidal activities in many pathogenic fungi is poorly understood. Here, Schuster, Kilaru & Steinberg show that azole lethality in the plant pathogens Zymoseptoria tritici and Magnaporthe oryzae is due to a combination of reactive oxygen species-induced apoptosis and macroautophagy. [ABSTRACT FROM AUTHOR]

This text explores the concept of rapid adaptation in biological systems, focusing on the impact of factors such as population size, genetic drift, and fluctuating selection. It provides examples from studies on yeast populations and host-parasite interactions to illustrate these concepts. The text emphasizes the importance of understanding the influence of demographic processes and environmental conditions on rapid adaptation, highlighting the complex interplay between ecological and evolutionary processes. [Extracted from the article]

The powdery mildew fungi (Erysiphaceae) are globally distributed plant pathogens with a range of more than 10,000 plant hosts. In this review, we discuss the long‐ and short‐term evolution of these obligate biotrophic fungi and outline their diversity with respect to morphology, lifestyle, and host range. We highlight their remarkable ability to rapidly overcome plant immunity, evolve fungicide resistance, and broaden their host range, for example, through adaptation and hybridization. Recent advances in genomics and proteomics, particularly in cereal powdery mildews (genus Blumeria), provided first insights into mechanisms of genomic adaptation in these fungi. Transposable elements play key roles in shaping their genomes, where even close relatives exhibit diversified patterns of recent and ongoing transposon activity. These transposons are ubiquitously distributed in the powdery mildew genomes, resulting in a highly adaptive genome architecture lacking obvious regions of conserved gene space. Transposons can also be neofunctionalized to encode novel virulence factors, particularly candidate secreted effector proteins, which may undermine the plant immune system. In cereals like barley and wheat, some of these effectors are recognized by plant immune receptors encoded by resistance genes with numerous allelic variants. These effectors determine incompatibility ("avirulence") and evolve rapidly through sequence diversification and copy number variation. Altogether, powdery mildew fungi possess plastic genomes that enable their fast evolutionary adaptation towards overcoming plant immunity, host barriers, and chemical stress such as fungicides, foreshadowing future outbreaks, host range shifts and expansions as well as potential pandemics by these pathogens. [ABSTRACT FROM AUTHOR]