For the pathogenicity test, smooth bromegrass seeds were steeped in water for four days, subsequently planted in six pots (diameter 10 cm, height 15 cm). These pots were maintained in a greenhouse environment, subject to a 16-hour photoperiod, with temperatures controlled between 20 and 25°C and a relative humidity of 60%. The microconidia of the strain, grown on wheat bran medium for 10 days, were purified by washing with sterile deionized water, then filtered through three sterile layers of cheesecloth. The concentration was quantified, and adjusted to 1 million microconidia per milliliter using a hemocytometer. Three pots of plants, upon reaching a height of about 20 centimeters, experienced foliar spraying with a spore suspension of 10 milliliters per pot, while the remaining three pots were treated with sterile water, functioning as a control (LeBoldus and Jared 2010). Cultivation of inoculated plants took place in an artificial climate box, with a 16-hour photoperiod, a temperature of 24 degrees Celsius and 60 percent relative humidity. After five days, the treated plants' leaves exhibited noticeable brown spots, contrasting with the unblemished leaves of the control group. From the inoculated plants, the same E. nigum strain was re-isolated, its identity confirmed via the morphological and molecular techniques outlined above. Our research indicates that this is the first documented case of E. nigrum-caused leaf spot disease on smooth bromegrass, observed both in China and across the entire globe. The quality and yield of smooth bromegrass could be diminished by the introduction of this pathogen. Due to this, it is imperative to formulate and implement management and control strategies for this disease.
Apple powdery mildew, caused by *Podosphaera leucotricha*, is an internationally widespread pathogen in apple-producing regions. When host resistance is inadequate, single-site fungicides offer the most efficient disease management in conventional orchards. Erratic precipitation and rising temperatures in New York State, a consequence of climate change, are likely to foster a more favorable environment for apple powdery mildew to flourish and propagate. In the described scenario, emerging outbreaks of apple powdery mildew could displace the established disease management protocols, including those targeting apple scab and fire blight. To date, no reports of fungicide-related control problems concerning apple powdery mildew have reached us from producers, yet the authors have witnessed and documented increased cases of the disease. Therefore, to maintain the potency of the single-site fungicide classes (FRAC 3 demethylation inhibitors, DMI; FRAC 11 quinone outside inhibitors, QoI; FRAC 7 succinate dehydrogenase inhibitors, SDHI), action was essential to evaluate the fungicide resistance status of P. leucotricha populations. In a two-year study (2021-2022), our team gathered a total of 160 samples of P. leucotricha from 43 orchards in New York's primary agricultural areas. These orchards were categorized as conventional, organic, low-input, and unmanaged systems. clinicopathologic feature Samples were screened for mutations in the target genes (CYP51, cytb, and sdhB), with a historical association to conferring fungicide resistance in other fungal pathogens to DMI, QoI, and SDHI fungicide classes, respectively. Histochemistry Across all samples, no mutations in target gene nucleotide sequences were found that translated into problematic amino acid changes. This implies that New York populations of P. leucotricha retain susceptibility to DMI, QoI, and SDHI fungicides, given that no additional resistance mechanisms are operative.
In the production of American ginseng, seeds hold a pivotal role. Pathogens utilize seeds as a significant vehicle for long-distance dissemination and survival strategies. Identifying the pathogens present in seeds forms the foundation for effective strategies to control seed-borne diseases. This paper investigated the fungi carried by American ginseng seeds from major Chinese production zones, using incubation and high-throughput sequencing as the primary methods. find more Seed-borne fungi were observed at a rate of 100%, 938%, 752%, and 457% in Liuba, Fusong, Rongcheng, and Wendeng, respectively. The isolation from the seeds yielded sixty-seven fungal species, categorized into twenty-eight genera. From the seed samples, eleven pathogenic agents were found to be present. All seed samples showed the presence of pathogens identified as Fusarium spp. The kernel's population of Fusarium species exceeded the shell's. The seed's shell and kernel exhibited significantly different fungal diversities, as indicated by the alpha index. Non-metric multidimensional scaling analysis produced results showcasing a pronounced separation of samples from different provinces and a clear distinction between seed shells and kernels. In American ginseng, the seed-borne fungi's response to four different fungicides varied significantly. Tebuconazole SC displayed the strongest inhibition (7183%), followed by Azoxystrobin SC (4667%), Fludioxonil WP (4608%), and Phenamacril SC (1111%). Fludioxonil, a standard seed treatment agent, demonstrated a modest reduction in the activity of fungi present on American ginseng seeds.
Global agricultural trade acts as a catalyst for the appearance and reappearance of fresh plant pathogens. The fungal pathogen Colletotrichum liriopes, a foreign quarantine concern for ornamental plants, particularly Liriope spp., continues to be a problem in the United States. East Asian records of this species on various asparagaceous hosts contrast with its single, initial report in the USA, which occurred in 2018. However, the identification in the study was constrained to ITS nrDNA data alone, without the benefit of a preserved culture or voucher specimen. The primary focus of this study was to ascertain the geographic and host distribution patterns of specimens categorized as C. liriopes. In order to achieve this objective, a comparative analysis was conducted on newly acquired and previously documented isolates, genetic sequences, and complete genomes derived from a range of host species and geographical regions (including, but not limited to, China, Colombia, Mexico, and the United States), juxtaposed against the ex-type specimen of C. liriopes. The isolates/sequences under investigation, subjected to multilocus phylogenetic analysis (utilizing ITS, Tub2, GAPDH, CHS-1, HIS3), phylogenomic studies, and splits tree analyses, displayed a robustly supported clade with minimal intraspecific variability. Morphological descriptions strengthen the validity of these findings. The Minimum Spanning Network, in combination with the low nucleotide diversity and negative Tajima's D values in both multilocus and genomic data, indicates a recent expansion of East Asian genotypes, initially to countries producing ornamental plants like South America, and ultimately to importing nations like the USA. Analysis of the study demonstrates that the geographic range and host diversity of C. liriopes sensu stricto have extended to encompass the United States (specifically, Maryland, Mississippi, and Tennessee), and now include various hosts beyond Asparagaceae and Orchidaceae. This research yields foundational knowledge applicable to minimizing agricultural trade expenses and losses, and to deepening our comprehension of pathogen transmission.
Among the most widely cultivated edible fungi globally, Agaricus bisporus holds a prominent place. In December 2021, a 2% occurrence of brown blotch disease was noted on the cap of A. bisporus, within a mushroom cultivation base in Guangxi, China. Initially, the cap of A. bisporus featured brown blotches, ranging in size from 1 to 13 centimeters, that grew progressively larger as the cap itself expanded. Two days later, the infection had reached the inner tissues of the fruiting bodies, manifesting as dark brown blotches. To isolate causative agents, infected stipe tissue samples (555 mm) were sterilized in 75% ethanol for 30 seconds, rinsed three times with sterile deionized water (SDW), and then mechanically disrupted within sterile 2 mL Eppendorf tubes. Subsequently, 1000 µL of SDW was added, and this suspension was serially diluted to achieve seven concentrations (10⁻¹ to 10⁻⁷). Following the application of each 120-liter suspension to Luria Bertani (LB) medium, the incubation process was maintained for 24 hours at a temperature of 28 degrees Celsius. Colonies of a whitish-grayish color, smooth and convex, held dominance. The culture of cells on King's B medium (Solarbio) revealed Gram-positive, non-flagellated, nonmotile characteristics, with no formation of pods or endospores and no production of fluorescent pigments. The 16S rRNA sequence (1351 bp; OP740790), amplified from five colonies using universal primers 27f/1492r (Liu et al., 2022), demonstrated a 99.26% sequence identity with Arthrobacter (Ar.) woluwensis. Using the method of Liu et al. (2018), amplification of the partial sequences for the ATP synthase subunit beta (atpD) gene (677 bp; OQ262957), RNA polymerase subunit beta (rpoB) gene (848 bp; OQ262958), preprotein translocase subunit SecY (secY) gene (859 bp; OQ262959), and elongation factor Tu (tuf) gene (831 bp; OQ262960) from colonies exhibited a similarity greater than 99% to Ar. woluwensis. Three isolates (n=3) underwent biochemical testing, using bacterial micro-biochemical reaction tubes provided by Hangzhou Microbial Reagent Co., LTD, resulting in the same biochemical characteristics observed in the Ar strain. Woluwensis strains exhibit a positive response in esculin hydrolysis, urea utilization, gelatin degradation, catalase activity, sorbitol metabolism, gluconate assimilation, salicin fermentation, and arginine utilization. Citrate, nitrate reduction, and rhamnose were not detected, as determined by Funke et al. (1996). Analysis of the isolates indicated they are Ar. The woluwensis species' identity is confirmed through a comparative study of its morphological attributes, its biochemical properties, and its phylogenetic relationship. Pathogenicity assays were executed on bacterial suspensions (1×10^9 CFU/ml), cultivated in LB Broth at 28°C with 160 rpm for 36 hours. Young Agaricus bisporus caps and tissues received a 30-liter addition of bacterial suspension.