For the pathogenicity analysis, smooth bromegrass seeds were soaked in water for four days, subsequently distributed into six pots (10 centimeters in diameter and 15 centimeters in height), and maintained within a greenhouse. These plants were exposed to a 16-hour photoperiod, with temperatures ranging from 20 to 25 degrees Celsius and a relative humidity of 60%. Microconidia produced on wheat bran medium after ten days, from the strain, were washed with sterile deionized water, filtered through three layers of sterile cheesecloth, quantified, and adjusted to a concentration of 1 x 10^6 microconidia per milliliter using a hemocytometer. At a height of approximately 20 centimeters, the foliage of three plant pots received a spore suspension application, 10 milliliters per pot, whereas the remaining three pots were treated with sterile water as a control group (LeBoldus and Jared 2010). Under a 16-hour photoperiod, and within an artificial climate box, inoculated plants were grown, keeping a consistent temperature of 24 degrees Celsius and a 60 percent relative humidity. Five days after treatment, the leaves of the treated plants displayed brown spots, while the control leaves maintained their healthy appearance. Employing the previously described methods of morphological and molecular analysis, the inoculated plants were shown to contain re-isolated E. nigum of the same strain. 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. Smooth bromegrass's agricultural output and quality might be affected by infection with this pathogen. For this purpose, plans for the administration and regulation of this illness should be crafted and put into action.
The worldwide presence of *Podosphaera leucotricha*, the agent of apple powdery mildew, demonstrates its endemic status in apple-producing regions. Conventional orchards, lacking durable host resistance, depend on single-site fungicides for the most efficient disease management. The emergence of erratic precipitation and warmer temperatures in New York, a result of climate change, could contribute to the advancement and dissemination of apple powdery mildew. This scenario suggests a potential shift in disease management priorities, where outbreaks of apple powdery mildew could take precedence over apple scab and fire blight. No reports of fungicide failure in controlling apple powdery mildew have been received from producers, although the authors have observed and documented a rise in disease prevalence. For the continued effectiveness of key single-site fungicide classes – FRAC 3 (demethylation inhibitors, DMI), FRAC 11 (quinone outside inhibitors, QoI), and FRAC 7 (succinate dehydrogenase inhibitors, SDHI) – a crucial step was to ascertain the fungicide resistance status of P. leucotricha populations. New York's key fruit production areas were sampled over two years (2021-2022) for 160 specimens of P. leucotricha, including examples from conventional, organic, low-input, and unmanaged orchard types found at 43 locations. biosafety analysis Screening samples for mutations in the target genes (CYP51, cytb, and sdhB), historically recognized for conferring fungicide resistance in other fungal pathogens to the DMI, QoI, and SDHI fungicide classes respectively, was performed. Genetic-algorithm (GA) Across every sample studied, no nucleotide sequence mutations were detected in the target genes that translated into problematic amino acid changes. This suggests that the New York P. leucotricha populations remain vulnerable to DMI, QoI, and SDHI fungicides, barring the presence of any other resistance mechanisms.
The propagation of American ginseng hinges crucially on the presence of seeds. The significant role seeds play in the far-reaching spread and the crucial survival of pathogens is undeniable. The pathogens carried by seeds serve as a key factor for the proper management of seed-borne diseases. High-throughput sequencing, combined with incubation techniques, was employed to identify and characterize the fungal organisms harbored by American ginseng seeds procured from key Chinese production areas in this research. selleck chemical In Liuba, Fusong, Rongcheng, and Wendeng, the percentages of seed-associated fungi were 100%, 938%, 752%, and 457% respectively. The isolation from the seeds yielded sixty-seven fungal species, categorized into twenty-eight genera. Analysis of seed samples identified a total of eleven pathogenic organisms. In each of the seed samples, the pathogens Fusarium spp. were found. The kernel harbored a greater concentration of Fusarium species than the shell. According to the alpha index, fungal diversity varied considerably between the seed shell and kernel. The application of non-metric multidimensional scaling to the data illustrated a notable separation of samples originating from different provinces, as well as a clear difference between seed shells and kernels. In American ginseng, seed-borne fungal populations showed varying susceptibility to fungicide treatments. Tebuconazole SC yielded a 7183% inhibition rate, while Azoxystrobin SC exhibited 4667%, Fludioxonil WP 4608%, and Phenamacril SC 1111% respectively. A low level of inhibition against seed-borne fungi of American ginseng was observed with the conventional seed treatment, fludioxonil.
A more prevalent aspect of global agricultural trade is the acceleration of newly emerging and recurring plant pathogens. In the United States, the fungal pathogen Colletotrichum liriopes is still a foreign quarantine concern, specifically affecting Liriope spp. ornamental plants. Despite its presence on various asparagaceous plants in East Asia, the species's initial and solitary report in the USA dates back to 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 present study's central objective was to identify the geographic and host range of samples classified as C. liriopes. A comparison of new and existing isolates, sequences, and genomes, sourced from diverse hosts and geographic locations (China, Colombia, Mexico, and the United States, for instance), was undertaken to achieve this. This analysis was carried out against the ex-type of C. liriopes. Phylogenetic analyses, encompassing multilocus data (ITS, Tub2, GAPDH, CHS-1, HIS3), phylogenomic approaches, and splits tree methodologies, demonstrated that all examined isolates/sequences clustered within a strongly supported clade exhibiting minimal intraspecific divergence. Morphological attributes provide compelling support for these results. The recent movement/invasion of a few East Asian genotypes, evidenced by the low nucleotide diversity, negative Tajima's D in both multilocus and genomic data, and the Minimum Spanning Network, suggests a dispersal from East Asia to ornamental plant production countries like South America, and subsequently 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. The findings of this investigation provide fundamental knowledge that will aid in decreasing agricultural trade losses and expenses, and in deepening our knowledge of how pathogens migrate.
One of the most extensively cultivated edible fungi found worldwide is Agaricus bisporus. The mushroom cultivation base in Guangxi, China, reported a 2% incidence of brown blotch disease on the cap of A. bisporus in December 2021. On the cap of A. bisporus, brown blotches of 1-13 cm in size first appeared, and then gradually increased in extent along with the growth of the cap. After two days, the infection had permeated the inner tissues of the fruiting bodies, leaving distinct dark brown blotches. To isolate the causative agent(s), 555 mm internal tissue samples from infected stipes were sterilized in 75% ethanol for 30 seconds, rinsed thrice with sterile deionized water (SDW), then homogenized in sterile 2 mL Eppendorf tubes. A volume of 1000 µL SDW was added, and the suspension was serially diluted into seven concentrations, ranging from 10⁻¹ to 10⁻⁷. Luria Bertani (LB) medium was used to distribute each 120-liter suspension, which was then incubated for 24 hours at 28 degrees Celsius. Colonies of a whitish-grayish color, smooth and convex, held dominance. No fluorescent pigments were produced, and no pods or endospores were formed by the Gram-positive, non-flagellated, and nonmotile cells growing on King's B medium (Solarbio). The amplified 16S rRNA gene (1351 base pairs; OP740790) from five colonies, employing universal primers 27f/1492r (Liu et al., 2022), exhibited a 99.26% sequence identity to Arthrobacter (Ar.) woluwensis. The colonies' partial sequences of the ATP synthase subunit beta gene (atpD) (677 bp; OQ262957), RNA polymerase subunit beta gene (rpoB) (848 bp; OQ262958), preprotein translocase subunit SecY gene (secY) (859 bp; OQ262959), and elongation factor Tu gene (tuf) (831 bp; OQ262960) demonstrated more than 99% similarity to Ar. woluwensis when amplified using the protocol of Liu et al. (2018). Biochemical analyses of the three isolates (n=3), conducted using bacterial micro-biochemical reaction tubes from Hangzhou Microbial Reagent Co., LTD, demonstrated the same biochemical traits as observed in Ar. Woluwensis strains exhibit a positive response in esculin hydrolysis, urea utilization, gelatin degradation, catalase activity, sorbitol metabolism, gluconate assimilation, salicin fermentation, and arginine utilization. According to Funke et al. (1996), the organism exhibited no citrate production, nitrate reduction, or rhamnose fermentation. The isolates, upon identification, proved to be Ar. Phylogenetic analysis, morphological characteristics, and biochemical assays converge to define the characteristics of woluwensis. Bacterial suspensions, cultivated in LB Broth at 28°C (160 rpm) for 36 hours (1×10^9 CFU/ml), underwent pathogenicity tests. The cap and tissue of young A. bisporus were treated with a 30-liter volume of bacterial suspension.