[Identification and biological characterization of pathogen causing black spot of Pseudostellaria heterophylla in Fujian province].

In Zherong county, Fujian province, the black spot of Pseudostellaria heterophylla often breaks out in the rainy season from April to June every year. As one of the main leaf diseases of P. heterophylla, black spot seriously affects the yield and quality of the medicinal material. To identify and characterize the pathogens causing black spot, we isolated the pathogens, identified them as a species of Alternaria according to Koch's postulates, and then tested their pathogenicity and biological characteristics. The results showed that the pathogens causing P. heterophylla black spot were A. gaisen, as evidenced by the similar colony morphology, spore characteristics, sporulation phenotype, and the same clade with A. gaisen on the phylogenetic tree(the maximum likelihood support rate of 100% and the Bayesian posterior probability of 1.00) built based on the tandem sequences of ITS, tef1, gapdh, endoPG, Alta1, OPA10-2, and KOG1077. The optimum conditions for mycelial growth of the pathogen were 25 ℃, pH 5-8, and 24 h dark culture. The lethal conditions for mycelia and spores were both treatment at 50 ℃ for 10 min. We reported for the first time the A. gaisen-caused black spot of P. heterophylla. The results could provide a theoretical basis for the diagnosis and control of P. heterophylla leaf spot diseases.

[Identification and biological characteristics of violet root rot pathogen of Pseudostellaria heterophylla in Fujian province].

Violet root rot is one of the main root diseases in the production process of Pseudostellaria heterophylla. To clarify the pathogenic species that cause the violet root rot of P. heterophylla in Fujian province, the roots and the sclerotia with violet root rot symptoms were collected from the main producing areas of P. heterophylla(Fujian province) from 2017 to 2021, and the pathogens were isolated by tissue separation method and identified by morphology and multi-gene phylogenetic analysis. Additionally, the biological characteristics of the pathogens were studied and the fungicides were determined. The results showed that 78 strains of violet root rot were isolated from the collected root samples, which belonged to one type after preliminary morphological identification. Two represen-tative strains were selected from the pathogens for multi-gene phylogenetic analysis, and they were clustered with Helicobasidium mompa together. The suitable culture conditions for the mycelium were OA medium, 25 ℃, pH 6, and ammonium oxalate as the nitrogen source. The lethal temperature of the mycelium was 50 ℃ for 10 minutes. Moreover, 99.1% propiconazole and 98.7% azoxystrobin had the optimal bacteriostatic effect, and the concentrations with the 50% bacteriostatic rate were 16.85 and 12.24 µg·mL~(-1), respectively. On the basis of the above results, the pathogen causing violet root rot of P. heterophylla in Fujian province was H. mompa. The medium type, growth temperature, pH value, nitrogen source, etc. had significant effect on the growth of mycelium.

First Report of Corynespora cassiicola Causing Leaf spot of Strobilanthes cusia in China.

Strobilanthes cusia (Nees) Kuntze is a vital medicinal and industrial herb, planted extensively in southern China (Hu, et al. 2011.). In July and August of 2021, leaf spot incidence on >60% plants and reduced yields >20% for fresh leaves were observed in S. cusia cultivar 'Malan No.1' across the Shufeng whole Township, Xianyou County, Fujian province. Initial symptoms on leaves were observed as small, dark-brown, spots surrounded by a yellow halo, expanding irregularly or into semicircular spots. As symptoms developed, the spots became dark brown, thin and fragile, forming small holes. In severe cases plants were defoliated. The pathogen was isolated from the margin of 60 symptomatic leaf lesions， surfacesterilized with 75% ethanol for 45 s, rinsed three times with sterile water, air dried, and cultured on PDA at 25°C in the dark. Pure cultures were obtained by single-spore isolation after subculture. Ten representative single-spore isolates (MY-1 to MY-10) from 154 pathogens in 10 sampling points were selected for morphological characterization and identification. After 7 days, mycelial colonies were gray to dark gray with few aerial hyphae. Conidia (32.3 to 132.8 × 5.8 to 8.4 µm, average 81.4 × 6.3 µm, n=50) were pale to brown, erect or curved, solitary or in chains, with 0 to 15 pseudosepta. Based on morphological characteristics, the isolates were preliminarily identified as Corynespora cassiicola. Genomic DNA of isolate MY-2 (randomly selected from 10 isolates as representative) was extracted from mycelia using the Ezup DNA extraction kit (Sangon Biotech Co., Ltd. Shanghai, China). The ITS (internal transcribed spacer) region of rDNA, TEF1-α (translation elongation factor 1 alpha) and TUB2 (beta-tubulin) genes were amplified and sequenced with primers ITS4/ITS5, EF1-728F/EF-986R (Wang et al. 2021) and Bt2a/Bt2b (Glass et al. 1995), respectively. BLASTN sequence analyses of ITS (538 bp), TEF1-α (302 bp) and TUB2 (436 bp) of isolate MY-2 (GenBank accessions OK355515, OM339443, OM339442) showed 100%, 97.6%, 100% identity with C. cassiicola in GenBank (Accession numbers JX908713, MW961421, AB539228). A neighbor-joining phylogenetic analysis based on ITS and TEF1-α sequences using MEGA7 showed that MY-2 clustered in the same clade with C. cassiicola. For pathogenicity tests, five S. cusia plants were inoculated onto the adaxial surface of leaves with mycelial plugs from ten isolates of 8-day-oldcultures on PDA. Five leaves per plant were inoculated, covered with wet cotton, and kept in a controlled greenhouse (26~33 °C, RH 80% ~ 90%). Leaves inoculated with sterile PDA plugs served as a negative control. At 3-5 days post inoculation, all 25 inoculated leaves of each isolate showed leaf spot lesions similar to those observed in the field, and control leaves were symptomless. C. cassiicola was successfully reisolated from the diseased leaves. The pathogenicity tests were repeated three times under the same conditions and similar results were observed. In view of morphology, pathogenicity and sequence results, the isolates were identified as C. cassiicola, a pathogen reported from many important crops (Lu et al. 2021). This is the first report of C. cassiicola as a pathogen in China which poses a potential threat to leaf production and S. cusia processing. References: Glass, N. L., et al. 1995. Appl. Environ. Microb. 61:1323 Hu, J.Q., et al. 2011. Flora of China. Science Press, Beijing, China. Volume 19: 407 Li, Q.L., et al. 2013. Plant Dis. 97 (5): 690 Lu, P. et al. 2021. Plant Dis. 105:3753 Wang S. H., et al. 2021.Forest Pathology, 51(2):1 Keywords: fungal disease, Strobilanthes cusia, medicinal plants, etiology, leaf spot.

Partially sintered copper‒ceria as excellent catalyst for the high-temperature reverse water gas shift reaction.

For high-temperature catalytic reaction, it is of significant importance and challenge to construct stable active sites in catalysts. Herein, we report the construction of sufficient and stable copper clusters in the copper‒ceria catalyst with high Cu loading (15 wt.%) for the high-temperature reverse water gas shift (RWGS) reaction. Under very harsh working conditions, the ceria nanorods suffered a partial sintering, on which the 2D and 3D copper clusters were formed. This partially sintered catalyst exhibits unmatched activity and excellent durability at high temperature. The interaction between the copper and ceria ensures the copper clusters stably anchored on the surface of ceria. Abundant in situ generated and consumed surface oxygen vacancies form synergistic effect with adjacent copper clusters to promote the reaction process. This work investigates the structure-function relation of the catalyst with sintered and inhomogeneous structure and explores the potential application of the sintered catalyst in C1 chemistry.

Aquagenic acrokeratoderma.

BACKGROUND: Aquagenic acrokeratoderma (AA) is a rare condition with female predilection that occurs after brief water exposure and disappears minutes to an hour after drying. The pathogenesis remains unclear. METHODS: Four Chinese patients with AA were reported and analyzed. RESULTS: There were 2 males and 2 females (age range: 14-33 years) who presented with a 2-week to more than 10-year history of small white papules coalescing into edematous plaques on the hands; lesions appeared within 5-10 minutes of water exposure, began to regress in 3-20 minutes and disappeared within 5 minutes to one hour after drying. Warm water provoked the lesions more rapidly than cold water. Lesions of a female patient could be triggered by detergent. In another female patient, lesions also involved the feet and were associated with palmoplantar erythema and hyperhidrosis. Biopsy from the lesion of one patient after water exposure revealed hyperkeratosis, mild hypergranulosis, and dilatated eccrine ducts. Biopsy from the lesion of another patient after drying showed normal epidermis and dermis. Two patients were treated with topical formalin 3% in alcohol, and two with 3% potassium aluminium sulfate solution with partial relief without any adverse effects. CONCLUSION: AA may occur in both males and females and may involve the feet. Warm water triggers the lesions more rapidly than cold. Topical formalin 3% in alcohol and 3% potassium aluminium sulfate solution may be optional therapy.