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Fusarium head blight (FHB) is a major disease worldwide on cultivated cereals, caused by several Fusarium species. FHB can cause not only yield reduction but also accumulation of mycotoxins in the grain contaminating the food supply. Much of the earlier research has focused on Fusarium pathogenesis, conditions required for disease development and toxin accumulation, and FHB management. However, the Fusarium community composition within the micro‐habitat of a single diseased wheat head in the field has had limited investigation. Similarly, the relationship between the Fusarium community structure and mycotoxin accumulation within diseased heads remains unclear. In the present study, we investigated the Fusarium community in diseased heads sampled from different geographical sites in China. Several sites in Shandong province formed a transitional region which contained highly variable profiles of Fusarium OTUs, where a single diseased head could contain more than 10 Fusarium OTUs. Mycotoxin accumulation was independent of geographical properties, however, deoxynivalenol, 15‐acetyldeoxynivalenol and zearalenone concentrations showed a significant negative correlation with Fusarium diversity on diseased heads while a significant positive correlation between nivalenol concentration and Fusarium diversity was observed. Taken together, the Fusarium OTU diversity within diseased heads in the field significantly influences mycotoxin accumulation, providing an important point to consider in FHB disease management and mycotoxin research. [ABSTRACT FROM AUTHOR]

A group of aggressive pathogens have evolved to colonize the plant xylem. In this vascular tissue, where water and nutrients are transported from the roots to the rest of the plant, pathogens must be able to thrive under acropetal xylem sap flow and scarcity of nutrients while having direct contact only with predominantly dead cells. Nevertheless, a few bacteria have adapted to exclusively live in the xylem, and various pathogens may colonize other plant niches without causing symptoms unless they reach the xylem. Once established, the pathogens modulate its physicochemical conditions to enhance their growth and virulence. Adaptation to the restrictive lifestyle of the xylem leads to genome reduction in xylem-restricted bacteria, as they have a higher proportion of pseudogenes in their genome. The basis of xylem adaptation is not completely understood; therefore, a need still exists for model systems to advance the knowledge on this topic. [ABSTRACT FROM AUTHOR]

The United States is the third largest producer of cotton and the largest exporter of cotton globally. Fusarium wilt, caused by the soilborne fungal pathogen Fusarium oxysporum f. sp. vasinfectum (Fov), was estimated to cause a $21 million cotton yield loss in 2022. Historically, Alabama was an important producer of cotton in the Southeastern United States and was the first state in which Fusarium wilt on cotton was described. To assess the genetic diversity of Fov field isolates in Alabama, 118 field isolates were collected from six counties across the state from 2014 to 2016. Phylogenetic analysis using TEF1 and RPB2 placed the Fov field isolates into 18 haplotypes. Upon profiling the Tfol transposon insertion in the NAT gene, it was determined that no race 4 isolates were recovered in Alabama. Representatives of all field isolate haplotypes caused disease on Upland cotton variety Rowden in a hydroponic test tube assay. Two haplotype A isolates were the most aggressive isolates recovered, and haplotype A isolate TF1 was more aggressive than the race 4 isolate 89-1A on Upland cotton and had similar symptom severity on Pima cotton. Karyotype profiling indicted an abundance of small chromosomes characteristic of karyotypes that include accessory chromosomes, with considerable variability between isolates. Collectively, our study indicates that Fov isolates from Alabama are genetically diverse, which may have been promoted by its persistence in cotton fields. [ABSTRACT FROM AUTHOR]

Plant diseases significantly impact food security and food safety. It was estimated that food production needs to increase by 50% to feed the projected 9.3 billion people by 2050. Yet, plant pathogens and pests are documented to cause up to 40% yield losses in major crops, including maize, rice, and wheat, resulting in annual worldwide economic losses of approximately US$220 billion. Yield losses due to plant diseases and pests are estimated to be 21.5% (10.1 to 28.1%) in wheat, 30.3% (24.6 to 40.9%) in rice, and 22.6% (19.5 to 41.4%) in maize. In March 2023, The American Phytopathological Society (APS) conducted a survey to identify and rank key challenges in plant pathology in the next decade. Phytopathology subsequently invited papers that address those key challenges in plant pathology, and these were published as a special issue. The key challenges identified include climate change effect on the disease triangle and outbreaks, plant disease resistance mechanisms and its applications, and specific diseases including those caused by Candidatus Liberibacter spp. and Xylella fastidiosa. Additionally, disease detection, natural and man-made disasters, and plant disease control strategies were explored in issue articles. Finally, aspects of open access and how to publish articles to maximize the Findability, Accessibility, Interoperability, and Reuse of digital assets in plant pathology were described. Only by identifying the challenges and tracking progress in developing solutions for them will we be able to resolve the issues in plant pathology and ultimately ensure plant health, food security, and food safety. [ABSTRACT FROM AUTHOR]

Plant diseases significantly impact food security and food safety. It was estimated that food production needs to increase by 50% to feed the projected 9.3 billion people by 2050. Yet, plant pathogens and pests are documented to cause up to 40% yield losses in major crops, including maize, rice, and wheat, resulting in annual worldwide economic losses of approximately US$220 billion. Yield losses due to plant diseases and pests are estimated to be 21.5% (10.1 to 28.1%) in wheat, 30.3% (24.6 to 40.9%) in rice, and 22.6% (19.5 to 41.4%) in maize. In March 2023, The American Phytopathological Society (APS) conducted a survey to identify and rank key challenges in plant pathology in the next decade. Phytopathology subsequently invited papers that address those key challenges in plant pathology, and these were published as a special issue. The key challenges identified include climate change effect on the disease triangle and outbreaks, plant disease resistance mechanisms and its applications, and specific diseases including those caused by Candidatus Liberibacter spp. and Xylella fastidiosa . Additionally, disease detection, natural and man-made disasters, and plant disease control strategies were explored in issue articles. Finally, aspects of open access and how to publish articles to maximize the Findability, Accessibility, Interoperability, and Reuse of digital assets in plant pathology were described. Only by identifying the challenges and tracking progress in developing solutions for them will we be able to resolve the issues in plant pathology and ultimately ensure plant health, food security, and food safety., Competing Interests: The author(s) declare no conflict of interest.

Verticillium wilt is primarily caused by the fungus Verticillium dahliae and represents one of the most important worldwide soilborne plant diseases. The causal agent can be spread by microsclerotia and conidia attached to seeds during national/international trade or in soil between fields. Consequently, accurate, sensitive, and rapid detection of V. dahliae from complex samples is critical for restricting entry of the pathogen to a new region/environment and enforcing early management of Verticillium wilt. Based on CRISPR/Cas12a and recombinant polymerase amplification (RPA) technologies, we developed an accurate, sensitive, and rapid detection method for V. dahliae with paper-based lateral flow strips. A highly efficient and specific CRISPR RNA (crRNA) was designed for the GAPDH gene of V. dahliae and was validated using several closely related Verticillium spp. Excluding the time required for the DNA extraction from the complex samples, a minimum of 40 min was required for the detection time. The RPA-CRISPR/Cas12a detection system had a lower detection limit of ∼10 copies of genomic DNA per reaction and was able to successfully detect as little as one microsclerotium per gram of soil. In addition, field samples displaying symptoms suggestive of V. dahliae were able to be positively identified for the presence of V. dahliae . Taken together, this study broadens the applications of CRISPR/Cas12a nucleic acid detection to soilborne crop diseases and will contribute to the future development of field-deployable diagnostic tools., Competing Interests: The author(s) declare no conflict of interest.

F. oxysporum is a notorious filamentous pathogenic fungus that causes serious problems in agriculture and animal/human health. Knowing how the fungus interacts throughout the course of an infection is necessary to propose an effective control strategy, and consequently the manipulation of the F. oxysporum genome is essential to investigate the molecular interplay between the host and fungus. To facilitate assessing protein quantification and subcellular localization, we developed a simple, economical CRISPR/Cas9-mediated endogenous gene tagging (EGT) system based on two different strategies, homology-independent targeted integration (HITI) and homology-dependent recombination integration (HDRI). Reporter genes, including GFP and LacZ, can be inserted at the N- or C-terminus of an endogenous gene of interest at the original chromosomal locus, allowing partial characterization of the gene function., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Plants produce low molecular weight compounds with antimicrobial activity in response to microbial attack termed phytoalexins. The first phytoalexin identified was (+) pisatin from pea, and several fungi are able to detoxify pisatin to a less inhibitory compound, including F. oxysporum f. sp. pisi. This detoxification is catalyzed by demethylation of the compound (termed pisatin demethylase activity, or PDA) by the cytochrome P450, Pda. Here we detail two procedures to assess PDA using radiolabeled [ 14 C]pisatin as a substrate and monitoring activity using a scintillation counter., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Characterization of a gene of interest frequently relies on generation of a mutant as a critical component. Transformation to disrupt a gene has been previously accomplished by several methods in Fusarium oxysporum. Here we provide a detailed method to generate a gene mutation mediated by a CRISPR/Cas9 ribonucleoprotein (RNP) complex. The Cas9 RNP cleaves the DNA at the target site, and during DNA repair integration of a dominant selectable marker is incorporated via homologous recombination generating the desired gene disruption., (© 2022. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)