First report of cobweb disease in Auricularia cornea caused by Hypomyces mycophilus in Guizhou, China.

Auricularia cornea is a widely cultivated mushroom in China, which has high medicinal values such as hemostaticity, analgesia, antioxidation and anti-tumor (Wu et al., 2019). In 2022, an investigation on edible mushroom diseases in Guizhou Province observed a suspected cobweb disease in an A. cornea growing factory, with up to 30% incidence. The pathogen first produced flocculent hyphae on the surface of the fruiting body of A. cornea, and then developed spider web-like aerial hyphae, covering the entire fruiting bodies. It hinders the normal growth of A. cornea, resulting in deformity and rot of the fruiting bodies. These symptoms seriously affect the quantity and quality of mushroom yields and cause huge economic losses. Three fungal isolates (GUCCX001, GUCCX002 and GUCCX003) were recovered from the diseased mushroom fruiting bodies and purified through single spore isolation. The colonies of three isolates spread rapidly on PDA, reaching 79-82 mm in seven days. The flocculent mycelium was whitish, and its reverse turned from yellowish to amber after 14 days. The branched conidiophores arising from aerial mycelia were septate and each cell contained several denticulate conidiogenous loci. Each denticle contained a single conidium. Conidia were observed at the tip of conidiophore branches and were 0-1-septate, oval or spherical, transparent, 5.2-11.3 × 11.7-18.7 µm (n = 35). Chlamydospores were visible as 3-4 thick-walled cells at the tip of lateral hyphal branches. Three isolates were tentatively identified as H. mycophilus based on their morphological characteristics similar to those described by Rogerson and Samuels (1993). The sequence of internal transcribed spacer (ITS) region (primers ITS5/ITS4) (Rehner and Samuels, 1994) and nuclear ribosomal large subunit (LSU) region (primers LR0R/LR5) (Vilgalys and Heste, 1990) of GUCCX001 (ITS: OP777905; LSU: OQ152071), GUCCX002 (ITS: OP862872; LSU: OQ152072) and GUCCX003 (ITS: OP862873; LSU: OP862873) were 99%-100% similar to H. mycophilus CBS 175.56 (ITS: MH857567; LSU: MH869110). Fifteen healthy fruiting bodies of A. cornea were inoculated by spraying spore suspension (106 conidia/mL) of the three isolates and five healthy fruiting bodies were sprayed with sterile water as control. All inoculated fruiting bodies were kept at 25 ℃. After three days, fruiting bodies of A. cornea treated with the spore suspension exhibited the same symptoms of cobweb as in the factory, while no symptom appeared in the control. Pathogens re-isolated from diseased fruiting bodies were confirmed to be H. mycophilus based on morphological characteristics, which fulfills the Koch's postulate. Zeng et al. (2017) reported H. mycophilus on the fruiting bodies of Auricularia sp. as a new record in Guangdong, China. H. mycophilus caused cobweb disease on A. auricula (Liu et al., 2020), A. cornea var. Li. (Cao et al., 2023) and A. heimuer (Zhang et al., 2023). To our knowledge, this is the first report of cobweb disease in A. cornea caused by H. mycophilus in Guizhou, China. Our findings will provide a basis for correct diagnosis and management of cobweb diseases on A. cornea.

The poplar pangenome provides insights into the evolutionary history of the genus.

The genus Populus comprises a complex amalgam of ancient and modern species that has become a prime model for evolutionary and taxonomic studies. Here we sequenced the genomes of 10 species from five sections of the genus Populus, identified 71 million genomic variations, and observed new correlations between the single-nucleotide polymorphism-structural variation (SNP-SV) density and indel-SV density to complement the SNP-indel density correlation reported in mammals. Disease resistance genes (R genes) with heterozygous loss-of-function (LOF) were significantly enriched in the 10 species, which increased the diversity of poplar R genes during evolution. Heterozygous LOF mutations in the self-incompatibility genes were closely related to the self-fertilization of poplar, suggestive of genomic control of self-fertilization in dioecious plants. The phylogenetic genome-wide SNPs tree also showed possible ancient hybridization among species in sections Tacamahaca, Aigeiros, and Leucoides. The pangenome resource also provided information for poplar genetics and breeding.

Global Methylomic and Transcriptomic Analyses Reveal the Broad Participation of DNA Methylation in Daily Gene Expression Regulation of Populus trichocarpa.

Changes in DNA methylation patterns in different tissues, at various developmental stages, and under environmental stimuli have been investigated in plants. However, the involvement of DNA methylation in daily gene expression regulation and the plant circadian clock have not been reported. Here, we investigated DNA methylomes and mRNA transcriptomes from leaves of P. trichocarpa over 24 h by high-throughput sequencing. We found that approximately 15.63-19.50% of the genomic cytosine positions were methylated in mature poplar leaves, with approximately half being in the form of asymmetric CHH sites. Repetitive sequences and transposable elements (TEs) were heavily methylated, and the hAT and CMC-EnSpm transposons were more heavily methylated than other TEs. High methylation levels were observed upstream and downstream of the transcribed region, medium in exon and intron, low in untranslated region (5'-UTR and 3'-UTR) of genic regions. In total, about 53,689 differentially methylated regions (DMRs) were identified and CHH context was the most abundant type among daily DNA methylation changes. The DMRs overlapped with over one third of the total poplar genes, including plant defense genes. In addition, a positive correlation between expression levels and DNA methylation levels in the gene body region were observed in DMR overlapping genes. About 1,895 circadian regulated genes overlapped with DMRs, with 871 hypermethylated genes with down-regulated expression levels and 881 hypomethylated genes with up-regulated expression levels, indicating the possible regulation of DNA methylation on the daily rhythmic expression of these genes. But rhythmic DNA methylation changes were not detected in any oscillator component genes controlling the plant circadian clock. Our results suggest that DNA methylation participates widely in daily gene expression regulation, but is not the main mechanism modulating the plant circadian clock.

[Blood levels of true insulin and immunoreactive insulin in evaluating beta-cell function with arginine stimulation test].

OBJECTIVE: To investigate the difference between serum true insulin (TI) and immunoreactive insulin (IRI) in evaluating islet beta-cell function and insulin resistance. METHODS: The arginine stimulation test was performed in 141 individuals, including 35 with normal glucose tolerance (NGT) and 106 with type 2 diabetes (T2DM). Plasma glucose (PG), TI, IRI and proinsulin (PI) levels were measured; the incremental value of TI/PG, (TI+PI)/PG and IRI/PG (delta TI/PG, delta(TI+PI)/PG and deltaIRI/PG) and the area under curve of TI/PG, (TI+PI)/PG and IRI/PG (AUC [TI/PG], AUC[(TI+PI)/PG] and AUC [IRI/PG]) after arginine stimulation were calculated to evaluate beta-cell function. RESULT: There were positive correlations of delta TI/PG with delta (TI+PI)/PG and delta IRI/PG in both NGT and T2DM patients (r=0.68 - 0.99, P<0.01). The similar correlations of AUC [TI/PG] with AUC [(TI+PI)/PG] and AUC [IRI/PG] were also shown (r=0.62 - 0.99, P<0.01). delta TI/PG was correlated with AUC [TI/PG] in two groups (NGT r=0.96, T2DM r=0.82, P<0.01). HOMA-IRTI, HOMA-IR(TI+PI) and HOMA-IRIRI in T2DM were higher than those in NGT (P<0.01). After arginine stimulation T2DM subjects mainly presented insulin resistance and decreased insulin secretion. CONCLUSION: The determination of TI may be more accurate than IRI in evaluating beta-cell function and insulin resistance.

[Relationship between the prevalence of microalbuminuria and components of metabolic syndrome in Shanghai].

OBJECTIVE: To study the relationship between the prevalence of microalbuminuria and components of metabolic syndrome in Shanghai. METHODS: A total of 3532 Shanghai Chinese (men 1622, women 1910) aged over 20 years were included. Body mass index (BMI), blood pressure, fasting plasma glucose, lipid profile and plasma insulin concentrations were measured in all subjects. Oral glucose tolerance test was performed in those subjects without knowing the diabetic history. Urinary albumin-to-creatinine ratio (ACR) was measured in an early morning spot urine sample. Microalbuminuria was diagnosed when ACR was between 30 and 300 mg/g. RESULTS: (1) The prevalence of microalbuminuria was increasing with aging (P < 0.001). When compared with subjects having normal ACR, the waist-hip ratio, systolic and diastolic pressure, serum triglyceride level, fasting plasma glucose and homeostasis model assessment-insulin resistance (HOMA-IR) were all significantly increased in those subjects with microalbuminuria. (2) Along with the increment of number of items on metabolic disorders, the prevalence of microalbuminuria was significantly increased (P for trend < 0.001). (3) Multiple logistic regression analyses revealed that hypertension and hyperglycemia were independent factors associated with microalbuminuria (OR = 2.15, P < 0.001 and OR = 1.64, P = 0.01 respectively). Those subjects with two or more items on metabolic disorders had higher odd ratio for the development of microalbuminuria (OR = 3.93 and 4.77, both P < 0.001) when compared with the subjects without metabolic disorder. CONCLUSION: The prevalence of microalbuminuria was independently associated with hypertension and hyperglycemia. The subjects with multiple metabolic abnormalities had higher risk for the development of microalbuminuria, especially in metabolic syndrome.