Peyronellaea arachidicola is the causal agent of peanut (Arachis hypogaea L.) web blotch. Here, we report an assembled draft genome sequence of P. arachidicola strain YY187 obtained from the symptomatic leaf of peanut in China. The genome size is 47.3 Mb, consisting of 26 contigs (N₅₀= 2.2 Mb) with G+C content of 56.37%. This genome will provide a valuable foundation for further research on genetics and comparative genomics of P. arachidicola.

Rehmannia glutinosa is one of the most important medicinal plants in China and is affected by viral diseases. In this study, a new virus tentatively named Rehmannia Allexivirus virus (ReAV) was identified through high-throughput sequencing, reverse-transcription polymerase chain reaction (RT-PCR), and Sanger sequencing. The complete genome length was 7297 nt and it contained five open reading frames (ORFs) encoding replicase, triple gene block 1(TGB1), TGB2, TGB3, and coat protein (CP). The replicase and CP presented nucleotide homology ranges of 59.9–65.2% and 47.5–55.5% between the nine ReAV isolates and the other 12 species of the genus Allexivirus. In the nine isolates, ReAV-20 and ReAV-31 isolates showed breakpoints in the replicase and CP regions, respectively. The other isolates shared 87.2–96.5% nt with the whole genome nucleotide identity. The phylogenetic tree showed that seven ReAV isolates based on replicase, CP, and whole genome sequences were clustered in the same branch and were related to the genus Allexivirus. The ReAV detection rates for 60 R. glutinosa samples were 73.3–81.7% through RT-PCR using primers targeting the replicase or CP genes. These results demonstrate that ReAV is the dominant virus in R. glutinosa. This study provides important evidence for understanding viruses infecting R. glutinosa and for establishing efficient strategies to prevent viral spread.

Epimedium [Epimedium sagittatum (Sieb. et Zucc.) Maxim., E. brevicornu Maxim., E. pubescens Maxim., E. koreanum Nakai] plants are perennial herbs and the dry leaves were used in traditional Chinese medicine with different medicinal effects (Chinese Pharmacopoeia, 2020 edition). In early August 2022 (the high temperature was 33 ℃ and the low temperature was 25 ℃ on average with above 70% relative humidity), large necrotized leaf spots were initially observed in one-year and two-year old E. sagittatum plants in Dengzhou (32°35'26.84" N, 112°11'8.37" E), Henan province, China. White mycelia, yellow and brown sclerotia were observed along the petioles and colonized to the back of leaves and also on soil-petioles interface around the diseased Epimedium plants. White mycelia spread rapidly from the disease plants as a center to neighboring plants and the infected plants eventually wilted. The disease incidence was 16.0% and 28.0% in the surveyed cultivation fields in Dengzhou (Henan) and Danjiangkou (Hubei), respectively, which resulted in above 20% of yield loss. The symptomatic tissues (petioles, n≥10) were cut into 0.5 cm sections with autoclaved scissors and surface sterilized with 75% ethanol for 30 s, followed by 3 min in 1% NaClO, rinsed three times with distilled sterile water, plated on autoclaved filter paper to remove excess moisture in a biological laminar hood, transferred onto potato dextrose agar (PDA) plates and incubated at 28℃ in incubator in the dark for 3-5 days. Twelve fungal isolates with white radial colony morphology were obtained and purified by hyphal-tip method. The isolates formed radial colonies showing abundant aerial mycelia with a growth rate of 19.25 to 22.25 mm/day (mean = 21.67 ± 0.77 mm; n = 36) and white abundant sclerotia were observed after 5-7 days post inoculation at 28℃. The hyphae of the isolates were hyaline, branched with clamp connections at septa. The isolates formed dark brown sclerotia on PDA plate post 10-14 days incubation. The diameter of mature brown sclerotia ranged from 1.31 to 3.07 mm (mean = 1.91 ± 0.39 mm; n = 40) and 13 to 45 sclerotia (mean = 28; n = 24) were observed on each Petri dish. The isolates were tentatively identified as Agroathelia rolfsii based on morphological characteristics (Yi Y., et al. 2024) and isolate YYHBJ1 was selected as representative isolate for molecular identification and pathogenicity test. The genomic DNA was extracted using CTAB method. For molecular identification, ITS region, translation elongation factor-1alpha (TEF-1α) and nuclear large-subunit ribosomal DNA (nLSU-rDNA) were amplified (White et al. 1990, Wendland and Kothe, 1997). The sequences 684-bp ITS (OR428367), 534-bp TEF1α (OR485567), and 965-bp nLSU-rDNA (OR426612) of isolate YYHBJ1 were deposited in GenBank. Sequence analysis revealed that ITS, TEF1α and nLSU-rDNA sequences of YYHBJ001 showed 100%, 99.63%, and 100% identity to ITS (MN380242 and JF819727), EF1α (MN262527) and nLSU-rDNA (MT225781 and AY635773) sequences of Agroathelia rolfsii (Sacc.) Redhead & Mullineux (Redhead and Mullineux 2023). Pathogenicity tests was confirmed by inoculating 1 year-old E. sagittatum plants grown in pots with sterile soil. PDA plug (5 mm diameter) colonized with 3 brown sclerotia and the fungal culture which was cultivated for 12 days was deposited beside the petiole on the surface of the soil. The control plants were inoculated with PDA plugs without the pathogen. Five plants were used in each treatment. The plants were cultivated in incubator at 28℃ with 80% relative humidity. Fourteen days later, white mycelia growing out from the sclerotia and spread along the petioles to the leave and the infected leaves were yellow. After 21 to 24 days, all inoculated plants displayed symptoms like those observed in field, while no symptoms were observed on the controls. The fungus was re-isolated from the inoculated plants as described above, fulfilling Koch's postulates. The pathogenicity tests were repeated three times. Based on morphological feature and DNA sequences, the pathogen of southern blight on Epimedium plants was identified as A. rolfsii (anamorph S. rolfsii). The pathogen A. rolfsii usually infect kinds of crops and cause southern blight, such as peanuts, chili peppers, green onion and so on (Daunde et al. 2018). To our knowledge, this is the first report of A. rolfsii causing southern blight on E. sagittatum plants in Henan in China.

The cultivated variety of Chinese yam (Dioscorea polystachya Turcz. cv. Tiegun) is an economically important plant, capable of producing tubers that are used as food and traditional Chinese medicine. The basal stem rot was found on approximately 65% of yam (tuber expansion stage) in a total of 10 ha field in Wuzhi, Wen, and Hua counties, Henan, China (Sep 2021). Dark brown fusiform lesions initially occurred at the stems basal, irregularly extending to join together and leading to loop-stem necrotic indentation. Three diseased samples from Wuzhi county were collected, cut into 5 × 5 mm pieces, surface sterilized in 75% ethanol (30 s) and 1% NaClO (1 min), washed in sterile water 3 times, and placed on PDA in the dark for 3 days at 28℃. A total of 44 isolates forming three groups of Fusarium colonies were obtained using monosporic isolation, of which 19, 8, and 17 isolates were identified as F. oxysporum, F. solani, and F. proliferatum based on colony morphology, respectively. Typical isolates SYJJ6, 9, and 10 for each group were further studied. The SYJJ6 colonies showed gray white abundant fluffy aerial mycelium with rough edges, formation of ellipsoid, unicellular microconidia without septa, 5.6 to 13.4 × 2.4 to 4.7 μm (n = 50), and sickle-shaped, slightly curved macroconidia with 2 to 4 septa, 14.0 to 23.9 × 3.4 to 5.1 μm (n = 50). Isolate SYJJ9 produced flocculent white colonies, grew in a circular pattern with a sharp edge, forming oval or oblong microconidia with zero or one septum, 11.2 to 18.8 × 3.4 to 6.2 μm (n = 50), and slightly curved macroconidia with 2 to 3 septa, 27.6 to 44.0 × 3.9 to 7.4 μm (n = 50). SYJJ10 produced whitish or pinkish white colonies with fluffy aerial mycelium and a red pigmentation, produced renal or oval microconidia with no septa, 5.1 to 11.8 × 1.8 to 4.2 μm (n = 50), and falcate, slightly curved macroconidia with 3 to 4 septa, 16.1 to 30.2 × 3.1 to 5.9 μm (n = 50). Additionally, TUB, EF-1α, and RPB2 genes were amplified with primers BT2a/BT2b, EF1/EF2, and 5f2/-7cr, respectively (Glass and Donaldson 1995; O'Donnell et al. 1998, 2010). BLASTn analysis on SYJJ6 (OR047663, OR047666, OR047669), SYJJ9 (OR047665, OR047667, OR047670), and SYJJ10 (OR047664, OR047668, OR047671) gene sequences were over 99% identical to those of F. oxysporum (100%, MK432917; 100%, MN417196; 99.61%, MN457531), F. solani (100%, MF662662; 100%, MN223440; 99.80%, CP104055), and F. proliferatum (100%, ON557521; 100%, ON458137; 99.90%, LT841266), respectively. Pathogenicity tests of three isolates were separately performed on 60-day-old yam seedlings. The basal stems were wounded using needle, and the wounds were wrapped with cotton balls soaked with conidial suspension (1 mL, 3×106 conidia/mL) or water (control). Each isolate treated three plants and repeated three times. All plants were grown at 28℃ under a 16/8-h light/dark cycle. Typical symptoms emerged on basal stems at 16, 13, and 17 days after inoculation with the conidia of isolates SYJJ6, 9, and 10, while the control basal stems appeared healthy. The re-isolated fungi were identical to the original three isolates. Fusarium species (F. oxysporum, F. commune, F. humuli, etc.)were previously reported to cause wilt or stem rot on different D. polystachya cultivars (Fang et al. 2020; Li et al. 2023; Zhao et al. 2013), or basal stem rot on Panax ginseng (Ma et al. 2020). This is the first report of Chinese yam basal stem rot caused by Fusarium species, which threatens the production of Chinese yam 'Tiegun' and should be further studied.