Corydalis acuminata Franch., C. edulis Maxim. and C. racemosa (Thunb.) Pers. of family Papaveraceae are rich in multiple alkaloids and widely used as Chinese medicinal herbs, for treating cough, pruritus, sores tinea and snake venom (Zhang et al. 2008, Iranshahy et al. 2014). In April 2021, orange rust pustules were observed on C. acuminata, C. edulis and C. racemosa in Shaanxi Province (34°4'56'' N, 108°2'9'' E, alt. 770 m), China. Samples were collected and voucher specimens were preserved in the Herbarium Mycologicum Academiae Sinicae (nos. HMAS249947-HMAS249949), China. Consequent geospatial investigations revealed that diseased plants can be observed at an altitude of 400-1000 m, and show an incidence from 40% to 80% varied by altitude. Spermogonia epiphyllous, subcuticular, densely grouped, oval or round, 0.14-0.36 × 0.09-0.30 mm, pale orange-yellow, and type 3 of Cummins and Hiratsuka (1963). Aecia mostly hypophyllous, subepidermal without peridia, Caeoma-type, erumpent, densely grouped, oval or round, 0.27-0.85 × 0.15-0.43 mm, and orange-yellow; hyaline peridial cells produced in a periphery of the sorus under the ruptured epidermis of host plants. Aeciospores globoid or broadly ellipsoid, catenulate with intercalary cells, 15.7-20.1 × 10.8-15.7 μm, yellow to pale orange; walls hyaline, verrucose, 1.7-3.1 μm thick. This fungus was morphologically identified as Melampsora (Melampsoraceae). The rDNA-28S and the internal transcribed spacer (ITS) regions were amplified using primers NL1/NL4 and ITS1/ITS4 (Ji et al. 2020; Wang et al. 2020). Bi-directional sequences were assembled and deposited in GenBank (accession nos. MW990091-MW990093 and MW996576-MW996578). Phylogenetic trees were constructed with the ITS+rDNA-28S dataset based on maximum-likelihood (ML), maximum-parsimony (MP) and Bayesian Inference (BI). ML and MP bootstrap values were calculated by bootstrap analyses of 1,000 replicates using MEGA-X (Kumar et al. 2018), while BI posterior probabilities (Bpps) were calculated using MrBayes ver. 3.1.2 (Ji et al. 2020; Wang et al. 2020). Phylogenetic analyses grouped our specimens and Melampsora ferrinii Toome & Aime into one clade, highly supported by bootstrap values of ML, MP, and Bpps of 100%/100%/1. Inoculations were conducted with 1-year-old plants of original host, Salix babylonica L. (Toome & Aime 2015). Aeciospores suspension with a concentration of 106 spores/ml were sprayed on 20 healthy leaves, with another 20 healthy leaves sprayed with sterile water as the control. The inoculated plants were kept in darkness at 20-25 °C for 2 days and then transferred into greenhouse at 23°C with 16 h light per day. After 8-10 days of inoculation, yellow pustules of uredinia appeared on abaxial surfaces of the inoculated leaves, which were identical to Toome & Aime (2015) reported, while the control leaves remained healthy. Inoculations with the same method were conducted by spraying urediniospores, and the same rust symptoms developed after 8 days. Genus Corydalis was verified as the alternate host of M. chelidonii-pierotii Tak. Matsumoto, M. coleosporioides Dietel, M. idesiae Miyabe and M. yezoensis Miyabe & T. Matsumoto (Shinyama & Yamaoka 2012; Okane et al. 2014; Yamaoka & Okane 2019), and C. incisa (Thunb.) Pers. was speculated as the potential alternate host of M. ferrinii (Toome & Aime 2015). Based on morphology, phylogeny and pathogenicity, we firstly report M. ferrinii in mainland China and verify C. acuminata, C. edulis and C. racemosa instead of C. incisa as its alternate hosts.

Melampsora larici-populina is a macrocyclic rust, and the haploid stage with two nuclei and the diploid of mononuclear sequentially occur annually. During the preservation of dry urediniospores at −80°C, we found that one isolate, ΔTs₀₆, was different from the usual wild-type isolate Ts₀₆ at −20°C because it has mixed polykaryotic urediniospores. However, the other spores, including the 0, I, III, and IV stages of a life cycle, were the same as Ts₀₆. After five generations of successive inoculation and harvest of urediniospores from the compatible host Populus purdomii, the isolate ΔTs₀₆ steadily maintained more than 20% multiple nucleus spores. To test the pathogenesis variation of ΔTs₀₆, an assay of host poplars was applied to evaluate the differences between ΔTs₀₆ and Ts₀₆. After ΔTs₀₆ and Ts₀₆ inoculation, leaves of P. purdomii were used to detect the expression of small secreted proteins (SSPs) and fungal biomasses using quantitative real-time PCR (qRT-PCR) and trypan blue staining. ΔTs₀₆ displayed stronger expression of five SSPs and had a shorter latent period, a higher density of uredinia, and higher DNA mass. A transcriptomic comparison between ΔTs₀₆ and Ts₀₆ revealed that 3,224 were differentially expressed genes (DEGs), 55 of which were related to reactive oxygen species metabolism, the Mitogen-activated protein kinase (MAPK) signaling pathway, and the meiosis pathway. Ten genes in the mitotic and meiotic pathways and another two genes associated with the “response to DNA damage stimulus” all had an upward expression, which were detected by qRT-PCR in ΔTs₀₆ during cryopreservation. Gas chromatography–mass spectrometry (GC-MS) confirmed that the amounts of hexadecanoic acid and octadecadienoic acid were much more in ΔTs₀₆ than in Ts₀₆. In addition, using spectrophotometry, hydrogen peroxide (H₂O₂) was also present in greater quantities in ΔTs₀₆ compared with those found in Ts₀₆. Increased fatty acids metabolism could prevent damage to urediniospores in super-low temperatures, but oxidant species that involved H₂O₂ may destroy tube proteins of mitosis and meiosis, which could cause abnormal nuclear division and lead to multinucleation, which has a different genotype. Therefore, the multinuclear isolate is different from the wild-type isolate in terms of phenotype and genotype; this multinucleation phenomenon in urediniospores improves the pathogenesis and environmental fitness of M. larici-populina.

During an investigation of the macrofungal flora in the Huanglong Mountains of the Loess Plateau, northwest China, a unique gomphoid fungus was discovered and collected. After morphological identification and molecular phylogenetic analyses, a new genus named Luteodorsum and its type species, L. huanglongense, were proposed. Phylogenetic analyses were conducted using datasets of nuclear ribosomal DNA 28S large subunit (LSU), mitochondrial (mt) adenosine triphosphatase (ATPase) subunit 6 (atp6), and mt small-subunit rDNA (mtSSU). The results confirmed that L. huanglongense forms an independent clade within Gomphales, with full maximum likelihood bootstrap support (MLBS), maximum parsimony bootstrap support (MPBS), and Bayesian posterior probability (BPP). L. huanglongense is characterized by its sandy-brown, orange-brown, or coffee-brown color; clavate to infundibuliform shape; wrinkled and ridged hymenophore; ellipsoid to obovoid warted basidiospores; cylindrical to clavate flexuous pleurocystidia; and crystal basal mycelium. Overall, this study contributes to the growing body of knowledge on the diversity and evolution of Gomphales and provides valuable insights into the unique fungal flora found in the Huanglong Mountains.

Melampsora larici-populina (Mlp), M. medusae (Mmed), M. magnusiana (Mmag), and M. pruinosae (Mpr) are epidemic rust fungi in China. The first two are macrocyclic rust fungi distributed in temperate humid environments. The latter two are hemicyclic rusts, mainly distributed in arid and semi-arid areas. Ontogenetic variation that comes with this arid-resistance is of great interest—and may help us predict the influence of a warmer, drier, climate on fungal phylogeny. To compare the differences in the life history and ontogeny between the two types of rust, we cloned mating type genes, STE3.4 and STE3.3 using RACE-smart technology. Protein structures, functions, and mutant loci were compared across each species. We also used microscopy to compare visible cytological differences at each life stage for the fungal species, looking for variation in structure and developmental timing. Quantitative PCR technology was used to check the expression of nuclear fusion and division genes downstream of STE3.3 and STE3.4. Encoding amino acids of STE3.3 and STE3.4 in hemicyclic rusts are shorter than these in the macrocyclic rusts. Both STE3.3 and STE3.4 interact with a protein kinase superfamily member EGG12818 and an E3 ubiquitin protein ligase EGG09709 directly, and activating G-beta conformational changes. The mutation at site 74th amino acid in the conserved transmembrane domain of STE3.3 ascribes to a positive selection, in which alanine (Ala) is changed to phenylalanine (Phe) in hemicyclic rusts, and a mutation with Tyr lost at site 387th in STE3.4, where it is the binding site for β-D-Glucan. These mutants are speculated corresponding to the insensitivity of hemicyclic rust pheromone receptors to interact with MFa pheromones, and lead to Mnd1 unexpressed in teliospora, and they result in the diploid nuclei division failure and the sexual stage missing in the life cycle. A Phylogenic tree based on STE3.4 gene suggests these two rust types diverged about 14.36 million years ago. Although these rusts share a similar uredia and telia stage, they show markedly different wintering strategies. Hemicyclic rusts overwinter in the poplar buds endophytically, their urediniospores developing thicker cell walls. They form haustoria with a collar-like extrahaustorial membrane neck and induce host thickened callose cell walls, all ontogenetic adaptations to arid environments.

White pine blister rust disease (WPBR), caused by Cronartium ribicola, ranks among the most destructive pathogens of five-needle pines. We developed a hydroxynaphthol blue (HNB)-based Loop-mediated isothermal amplification (LAMP) assay enabling rapid, visual detection of C. ribicola directly following DNA extraction. LAMP primers targeting the internal transcribed spacer (ITS) region were designed and validated through in silico comparison with related Cronartium species and in vitro testing against sympatric forest fungi. The optimized 25 μL reaction contained 8.0 mM Mg²⁺, 1.0 mM dNTPs, and an inner-to-outer primer ratio of 8:1, with amplification conducted at 62 °C for 40 min. Positive amplification produced a distinctive color transition from purple to sky blue, enabling visual interpretation without instrumentation. Under the tested conditions, the assay achieved a detection limit of 460 ± 3.2 fg/μL genomic DNA—a 10-fold improvement over conventional PCR in concentration-based sensitivity. Assay applicability was evaluated using 211 field-collected Pinus armandii samples sourced from China. Detection efficiency varied significantly across tissue types. Symptomatic bark exhibited a substantially higher positive detection rate (68.97%, 95% CI: 49.2–84.7%) compared to needles from symptomatic trees (18.75%, 95% CI: 4.1–45.7%). Among asymptomatic samples, 3.75% of bark samples tested positive for C. ribicola DNA, whereas all needle samples were negative. Geographically, positive detections clustered at several discrete sampling sites in southwestern China, predominantly at elevated elevations. The established LAMP-HNB assay provides a rapid, visually interpretable diagnostic tool for early detection and quarantine monitoring of WPBR following DNA extraction. Beyond its practical utility, this assay establishes valuable baseline data for targeted disease surveillance in the context of evolving climate conditions.

The genus Sawadaea (Erysiphales, Erysiphaceae) comprises obligate parasitic fungi that cause powdery mildew diseases primarily on maples (Acer spp.). During a mycological survey in the Qinling Mountains, China, distinctive powdery mildew specimens were collected from leaves of Acer stachyophyllum subsp. betulifolium. To elucidate its taxonomic status, we conducted comprehensive morphological characterization using light microscopy and molecular phylogenetic analyses based on a concatenated ITS and LSU dataset. The fungus is distinguished from all previously described Sawadaea species by its unique chasmothecia bearing numerous dichotomously to trichotomously branched appendages with up to 12 ultimate branchlets. Phylogenetically, the specimens form a monophyletic clade with strongly supported values of ML/MPBS = 100% and BPP = 1.0, within the genus Sawadaea. Based on this congruent morphological and phylogenetic evidence, the fungus is formally described herein as a new species, Sawadaea taibaishanensis sp. nov.