phytopathology

Aerial blight, caused by the fungus Rhizoctonia solani anastomosis group (AG) 1-IA, is an economically important soybean disease in the mid-Southern US. Management has relied on fungicide applications during the season, but there is an increasing prevalence of resistance to commonly used strobilurin fungicides and an urgent need to identify soybean varieties resistant to aerial blight. Since the patchy distribution of the pathogen complicates field variety screening, the present study aimed to develop a greenhouse screening protocol to identify soybean varieties resistant to aerial blight...

Transcription factors play critical roles in diverse biological processes in fungi. XlnR, identified as a transcriptional activator that regulates the expression of the extracellular xylanase genes in fungi, has not been extensively studied for its function in fungal development and pathogenicity in rice false smut fungus Ustilaginoidea virens. In this study, we characterized UvXlnR in U. virens and established that the full-length, N- and C-terminal forms of the UvXlnR have the ability to activate transcription...

Sclerotinia stem rot (SSR) is a globally destructive plant disease caused by Sclerotinia sclerotiorum . Current management of SSR primarily relies on chemical fungicides and crop rotation, raising environmental concerns. In this study, we developed an eco-friendly RNA bio-fungicide targeting S. sclerotiorum . Six S. sclerotiorum genes were selected for dsRNA synthesis. Four genes, including a Chitin binding domain (CBD), Mitogen-activated protein kinase (MAPK), oxaloacetate acetylhydrolase (OA), and Abhydrolase-3 (Abh), were combined to express hairpin RNA in E...

Biological control agent (BCA) Bacillus subtilis formulated as Theia® is registered for control of fungal and bacterial diseases of fruit crops. Combinations of Theia® and strategic concentrations of two demethylation inhibitor (DMI) fungicides were investigated to explore potential synergisms. Bacteria were cultured in nutrient broth and combined with technical grades and two formulations of propiconazole (EC and WP) and metconazole (EC and WDG) at 0, 10, 50, 100, and 150 µg/ml active ingredient...

Development of durable resistance effective against a broad range of pathotypes is crucial for restoration of pathogen-damaged ecosystems. This study dissected the complex genetic architecture for limber pine quantitative disease resistance (QDR) to Cronartium ribicola using a genome-wide association study (GWAS). Eighteen-month-old seedlings were inoculated for resistance screening under controlled conditions. Disease development was quantitatively assessed for QDR-related traits over four years post inoculation...

Growers have depended on the specificity and efficacy of streptomycin and oxytetracycline as a part of their plant disease arsenal since the middle of the twentieth century. With climate change intensifying plant bacterial epidemics, the established success of these antibiotics remains threatened. Our strong reliance on certain antibiotics for devastating diseases eventually gave way to resistance development. Though antibiotics in plant agriculture equal to less than 0.5% of overall antibiotic use in the US, it is still imperative for humans to continue to monitor usage, environmental residues, and resistance in bacterial populations...

Citrus Huanglongbing (HLB) caused by Candidatus Liberibacter asiaticus (CLas) is the most devastating citrus disease worldwide. CLas induces systemic and chronic reactive oxygen species (ROS) production, which was suggested to be a primary cause of cell death in phloem tissues and subsequent HLB symptoms. Mitigating oxidative stress caused by CLas using horticultural approaches has been suggested to a useful strategy to reduce HLB damages. To provide the information regarding the application timing to mitigate ROS, we investigated monthly dynamics of CLas concentration, CLas-triggered ROS, and phloem cell death in the bark tissues of asymptomatic and symptomatic branches of HLB-positive Hamlin and Valencia sweet orange trees in the field...

Unraveling the intricacies of soybean cyst nematode ( Heterodera glycines ) race 4 resistance and susceptibility in soybean breeding lines-11-452 (highly resistant) and Dongsheng1 (DS1, highly susceptible)-was the focal point of this study. Employing cutting-edge N6-methyladenosine (m6A)-seq and RNA-seq techniques, we delved into the impact of m6A modification on gene expression and plant defense responses. Through the evaluation of nematode development in both resistant and susceptible roots, a pivotal time point (3 days post inoculation) for m6A methylation sequencing was identified...

Bursaphelenchus xylophilus , the pine wood nematode (PWN), is the causal agent of pine wilt disease (PWD), which causes enormous economic loss annually. According to our previous research, fomepizole, as a selective inhibitor of PWN alcohol dehydrogenase (ADH), has the potential to be a preferable lead compound for developing novel nematicides. However, the underlying molecular mechanism is still unclear. The result of molecular docking showed that the stronger interactions between fomepizole and PWN ADH at the active site of ADH were attributed to hydrogen bonds...

HC-Pro and CP genes of a potyvirus facilitate cell-to-cell movement and are involved in the systemic movement of the viruses. The interaction between HC-Pro and CP is mandatory for aphid transmission. Two turnip mosaic virus (TuMV) isolates, RC4 and YC5, were collected from calla lily plants in Taiwan. The virus derived from the infectious clone pYC5 cannot move systemically in Chenopodium quinoa plants and lacks aphid transmissibility in Nicotiana benthamiana plants, like the initially isolated virus. Sequence analysis revealed that two amino acids P5 and A206, of YC5 CP uniquely differ from RC4 and other TuMV strains...

Scald is one of the major economically important foliar diseases in barley, causing susceptible varieties up to 40% of yield loss. The identification of quantitative trait loci (QTL) and elite alleles that confer resistance to scald is imperative in reducing the threats to barley production. In this study, genome-wide association studies (GWAS) were conducted using a panel of 697 barley genotypes to identify QTL for scald resistance. Field experiments were conducted over three consecutive years. Among different models used for GWAS analysis, FarmCPU was shown to be the best-suited model...

Sugar beet (Beta vulgaris L.) is grown in temperate regions around the world as a source of sucrose. Sugar beet is susceptible to a number of viral diseases, but identification of the causal agent(s) under field conditions is often difficult due to mixtures of viruses that may be responsible for disease symptoms. In this study, the application of RNAseq to RNA extracted from diseased sugar beet roots obtained from the field and from greenhouse-reared plants grown in soil infested with the virus disease rhizomania (causal agent, Beet necrotic yellow vein virus; BNYVV) yielded genome-length sequences from BNYVV as well as Beet soil-borne virus (BSBV)...

Calcium deficiency is a leading cause of reduced peanut (Arachis hypogaea) seed quality and has been linked to increased disease susceptibility, specifically to soil borne fungal pathogens. Sufficient calcium at flowering time is critical to ensure proper pod development. Calcite Dissolving Bacteria (CDB) isolated from farming fields can dissolve calcite (CaCO3) on plates and increase soluble calcium levels in soil. However, the phylogenetic diversity and geographic distribution of CDB is unclear. Here, we surveyed soil samples from fifteen peanut producing fields in three regions in southern Georgia, representing distinct soil compositions...

Pine, an evergreen conifer, is widely distributed worldwide. It is economically, scientifically, and ecologically important. However, pine wilt disease (PWD) induced by the pine wood nematode (PWN) adversely affects pine trees. Many studies have been conducted on PWN and their beetle vectors to prevent the spread of PWD. However, studies providing a comprehensive understanding of the pine tree transcriptome in response to PWN infection are lacking. Here, we performed temporal profiling of the pine tree transcriptome using PWD-infected red pine trees, Pinus densiflora, inoculated with PWN by RNA-sequencing...

Deoxynivalenol (DON) is the most widespread mycotoxin contaminant hazardous to human and animal health globally. It acts as a crucial virulence factor to stimulate the spread of pathogenic Fusarium within wheat plants. Control of DON and Fusarium disease contributes enormously to food safety, which relies on chemical fungicides. Here, we report the biodegradation of DON using a novel soil bacterium, Devosia insulae FS10-7, and the biocontrol effect of that against Fusarium crown rot (FCR). We demonstrated that strain FS10-7 degraded DON to 3-epi-DON by forming a 3-keto-DON intermediate...

Traditional monitoring of asian soybean rust severity is a time- and labor-intensive task, as it requires visual assessments by skilled professionals in the field. Thus, the use of remote sensing and machine learning (ML) techniques in data processing has emerged as an approach that can increase efficiency in disease monitoring, enabling faster, more accurate and time- and labor-saving evaluations. The aims of the study were: (i) to identify the spectral signature of different levels of Asian soybean rust severity; (ii) to identify the most accurate machine learning algorithm for classifying disease severity levels; (iii) which spectral input provides the highest classification accuracy for the algorithms; (iv) to determine a sample size of leaves that guarantees the best accuracy for the algorithms...

We revisit the foundations of the Horsfall-Barratt (HB) scale, a widely cited and applied plant disease visual assessment tool introduced in 1945, a full 37 years prior to T. T. Hebert's 1982 critique that raised concerns regarding the scale's rationale, particularly its reliance on the Weber-Fechner law and visual perception assumptions. Although use of the HB scale and similar ordinal scales persists, comprehensive studies have revealed that direct visual estimation using percentage scales often proves more accurate and reliable...

The genetic erosion of the European grapevine diversity in the last century has promoted the conservation of varieties in germplasm banks to prevent their disappearance. The study of these varieties is necessary as it would allow the diversification of the wine market, as well as provide a source of genes to face new pathogens or climate constraints. In this work, the grapevine varieties preserved in the "Estación de Viticultura e Enoloxía de Galicia" (EVEGA) Germplasm Bank (Ourense, Spain) were widely characterized, combining ampelography, ampelometry, agronomy, and phytopathology...

CRISPR has been widely characterized as a defense system against phages and other invading elements in bacteria and archaea. A low percentage of Ralstonia solanacearum species complex (RSSC) strains possess the CRISPR array and the CRISPR-associated proteins (Cas) that would confer immunity against various phages. In order to provide a wide-range screen of the CRISPR presence in RSSC, we analyzed 378 genomes of RSSC strains to find the CRISPR locus. We found that 20.1%, 14.3%, and 54.5% of the R. solanacearum, R...

The image-based detection and classification of plant diseases has become increasingly important to the development of precision agriculture. We consider the case of tomato, a high-value crop supporting the livelihoods of many farmers around the world. Many biotic and abiotic plant health issues impede the efficient production of this crop, and laboratory-based diagnostics are inaccessible in many remote regions. Early detection of these plant health issues is essential for efficient and accurate response, prompting exploration of alternatives for field detection...