Phytopathology

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...

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...

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...

This study provides the first report of a quantitative trait locus (QTL) in maize (Zea mays) for resistance to the southern root-knot nematode (SRKN) (Meloidogyne incognita). The SRKN can feed on the roots of maize in the U.S. Southern Coastal Plain region and can cause yield losses of 30% or greater in heavily infested fields. Increases in SRKN density in the soil may reduce the yield for subsequently planted susceptible crops. The use of maize hybrids with resistance to SRKN could prevent an increase in SRKN density, yet no genetic regions have been identified that confer host resistance...

The loss of the soil fumigant methyl bromide (MeBr) and adoption of soil fumigant alternatives has been challenging for farmers, particularly for those crops in which pathogens previously controlled by MeBr have emerged as significant problems, but it has resulted in some unanticipated benefits for the scientific community and the environment. Applauded as one of the most effective environmental agreements to date, the universally accepted Montreal Protocol on Ozone Depleting Substances has had a significant impact on the environment, reducing the release of halogenated compounds from anthropogenic sources enough to mitigate global warming by an estimated 1...

Sustainable production of pome fruit crops is dependent upon having virus-free planting materials. The production and distribution of plants derived from virus- and viroid-negative sources is necessary not only to control pome fruit viral diseases but also for sustainable breeding activities, as well as the safe movement of plant materials across borders. With variable success rates, different in vitro-based techniques, including shoot tip culture, micrografting, thermotherapy, chemotherapy, and shoot tip cryotherapy, have been employed to eliminate viruses from pome fruits...

Maize lethal necrosis (MLN) is a viral disease caused by host co-infection by maize chlorotic mottle virus (MCMV) and a potyvirus, such as sugarcane mosaic virus (SCMV). The disease is most effectively managed by growing MLN-resistant varieties. However, the relative importance of MCMV and potyvirus resistance in managing this synergistic disease is poorly characterized. In this study, we evaluated the effects of SCMV and/or MCMV resistance on disease, virus titers, and synergism and explored expression patterns of known potyvirus resistance genes TrxH and ABP1...

Wheat sheath blight caused by the necrotic fungal pathogen Rhizoctonia cerealis is responsible for severe damage to bread wheat. Reactive oxygen species (ROS) are vital for stress resistance by plants and their homeostasis plays an important role in wheat resistance to sheath blight. Valine-glutamine (VQ) proteins play important roles in plant growth and development, and responses to biotic and abiotic stresses. However, the functional mechanism mediated by wheat VQ protein in response to sheath blight via ROS homeostasis regulation is unclear...

Coffee fruit rot (CFR) is a well-known disease worldwide mainly caused by Colletotrichum spp., the most important species being C. kahawae subsp. kahawae . In Puerto Rico, Colletotrichum spp. were identified as pathogens of coffee fruits. The coffee berry borer (CBB) was shown to be a dispersal agent of these fungi and the role of Fusarium affecting coffee fruits was suggested. In this study we demonstrated that Fusarium spp. also cause CFR in Puerto Rico. Fusarium spp. are part of the CBB mycobiota, and this insect is responsible for spreading the pathogens in coffee fields...