Rhizome rot is a destructive soil-borne disease of Polygonatum kingianum and adversely affects the yield and sustenance of the plant. Understanding how the causal fungus Fusarium oxysporum infects P. kingianum may suggest effective control measures against rhizome rot. In germinating conidia of infectious F. oxysporum, expression of the zinc finger transcription factor gene Zfp1, consisting of two C₂H₂ motifs, was up-regulated. To characterize the critical role of ZFP1, we generated independent deletion mutants (zfp1) and complemented one mutant with a transgenic copy of ZFP1 (zfp1 tZFP1). Mycelial growth and conidial production of zfp1 were slower than those of wild type (ZFP1) and zfp1 tZFP1. Additionally, a reduced inhibition of growth suggested zfp1 was less sensitive to conditions promoting cell wall and osmotic stresses than ZFP1 and zfp1 tZFP1. Furthermore pathogenicity tests suggested a critical role for growth of zfp1 in infected leaves and rhizomes of P. kingianum. Thus ZFP1 is important for mycelial growth, conidiation, osmoregulation, and pathogenicity in P. kingianum.

Paris polyphylla var. yunnanensis is a perennial herb with diverse chemical components having wide-ranging pharmacological effects. The demand for P. polyphylla var. yunnanensis as a raw material i...

Angelica sinensis (Oliv.) Diels, is a perennial herbaceous plant of the Umbelliferae family. It has a long history of cultivation and is highly valued as a traditional Chinese medicine in China (Zhang et al. 2012). In September 2023, leaf blight on A. sinensis with an average disease incidence of 56% was recorded in an approximately 6.7-ha production field in Lijiang, Yunnan province, China (26.8215°N, 100.2369°E). At first, small, chlorotic lesions appeared on the leaves. They subsequently increased in density and gradually merged, causing leaves to yellow and wither. Ultimately the blight casused death of the entire foliage. In order to identify the causal agent, cross-sectional segments (5×5 mm2) were cut from the edge of leaf lesions, surface disinfected with a 1% sodium hypochlorite solution for 3 min and rinsed three times with sterile distilled water. They were subsequently placed on potato dextrose agar (PDA) plates and incubated for 3 days under a 12-h photoperiod at 28℃. A total of ten isolates with similar morphological characteristics were obtained by single spore isolation. After 10 days of incubation on PDA, the colony morphology of these isolates was characterized by a brownish central area with a white edge. Aged colonies became wrinkled in the center of the colony. Conidia (n = 30) were elliptical and brown, with a size range of 4.11 to 6.55 μm (average 5.37±0.74 μm) × 3.17 to 4.62 μm (average 3.92±0.43 μm). Chlamydospores (n = 30) formed chains in series, spherical or elliptical in shape, ranging from yellow-brown to dark brown, with a size range of 12.30 to 13.70 μm (average 12.98±0.46 μm) × 4.20 to 5.30 μm (average 4.63±0.26 μm). The nuclear ribosomal internal transcribed spacer region (ITS), the second largest subunit of RNA polymerase II (RPB2), and the 28S nuclear ribosomal large subunit rRNA (LSU) region of two isolates were amplified with the primer pairs ITS1/ITS4 (White et al. 1990), fRPB2-5F/fRPB2-7cR (Liu et al. 1999), and LR0R/LR5 (Schoch et al. 2012), respectively. These amplicons were sequenced bidirectionally and assembled. The two isolates produced the same nucleotide sequences, and the sequences of a representative isolate (AsDp1) were deposited in GenBank. BLASTn analyses showed that the ITS (PP510616), RPB2 (PP526010), and LSU (PP550143) sequences of isolate AsDp1 were 100%, 99.66%, and 100% identical with those of Didymella pomorum ex-type isolate CBS 354.52 (MH857081, KT389616, and MH868616), respectively. A phylogenetic tree was constructed based on the ITS, RPB2, and LSU concatenated nucleotide sequences using the maximum likelihood method in MEGAX. Isolate AsDp1 was clustered with four D. pomorum isolates. According to the morphological and nucleotide sequences analyses, isolate AsDp1 was identified as D. pomorum (Chen et al. 2015). To determine pathogenicity, 1-year-old A. sinensis plants (approximately 20 cm tall) grown in 7-liter pots filled with sterilized field soil were sprayed until runoff with a 1×106 conidia/ml suspension of isolate AsDp1 onto the foliage, while control plants were sprayed with sterile water. All plants were cultivated under a 12-h photoperiod at 25℃. The pathogenicity tests were performed in triplicate with ten plants in each treatment. After fifteen days, numerous chlorotic lesions appeared on the leaves of all inoculated plants. The symptoms were similar to those found on naturally infected plants in the field, while the control plants remained asymptomatic. Subsequently, D. pomorum was reisolated from the diseased leaves, and the identity was confirmed based on its ITS sequence and morphological characteristics. D. pomorum causing stem canker on Rosa spp. was reported in Canada (Ilyukhin 2022). To our knowledge, this is the first report of D. pomorum causing leaf blight on A. sinensis in China. This etiological finding will potentially pave the way for the development of control strategies of this disease.

Fusarium oxysporum strain PkF01 is the causal agent of Polygonatum kingianum rhizome rot. Here, we report, for the first time, the genome assemblies of the F. oxysporum strain PkF01 using the PacBi...

Stephania epigaea Lo is an herb of significant medicinal and ornamental value in China. In May 2024, leaf spot disease was observed on S. epigaea in the medicinal plant nursery base of Yunnan University of Chinese Medicine, Kunming, Yunnan Province, China (24°33'59.21"N, 99°55'43.71"E), with an incidence rate of 75%. The symptomatic leaves exhibited irregular brown lesions along the margins, surrounded by a yellow halo. To determine the causal agents, symptomatic leaf tissues (5 × 5 mm) were excised, surface-sterilized in 75% ethanol for 30 s, followed by immersion in 1% sodium hypochlorite (NaClO) for 180 s, and rinsed three times with sterile distilled water. The sterilized tissues were transferred onto potato dextrose agar (PDA) and incubated at 28°C in the dark for 3 d. Pure cultures were obtained using the single-spore purification method. A total of five single-spore isolates were obtained. The isolates exhibited white, cottony aerial mycelia with undulated colony margins. Conidia were fusiform and four-septate, with three versicolor median cells and hyaline apical and basal cells (17.3-26.8 µm long × 3.7-6.2 µm wide; n = 30). The apical cells bore two to three appendages (19.6-28. 6 μm long; n = 30), while the basal cells bore a single unbranched appendage. To further identify the fungus, isolate SeF01 was randomly selected for sequencing. The nuclear ribosomal internal transcribed spacers (ITS), large subunit ribosomal RNA gene (LSU), β-tubulin gene (TUB2), and translation elongation factor-1α (TEF-1α) regions were amplified and sequenced using primer pairs ITS1/ITS4 (White et al., 1990), LR0R/LR5 (Schoch et al., 2012), T1/T2 (O'Donnell and Cigelnik, 1997), and EF1-728F/EF1-986R (Carbone and Kohn, 1999), respectively. BLASTn homology analysis revealed that the ITS (GenBank accession no. PV363391), LSU (PV363539), TUB2 (PV384116), and TEF-1α (PV384117) sequences of isolate SeF01 exhibited 99.44-100% identity with Neopestalotiopsis rosae strain CBS 101057 (KM199359, KM116245, KM199429, and KM199523). A phylogenetic tree of Neopestalotiopsis species was built based on concatenated nucleotide sequences of ITS, LSU, TUB2, and TEF-1α using the maximum likelihood method. Isolate SeF01 clustered with N. rosae on the same branch. Morphological and molecular analyses confirmed that SeF01 was identical to N. rosae. To confirm pathogenicity of the isolate, conidial suspension with 1 × 106 conidia/mL was sprayed onto S. epigaea plants until runoff, while the control plants were sprayed with sterile distilled water. Two replicates (6 plants/replicates) were performed. All plants were incubated at 28℃ and 80% relative humidity with a 12 h light/12 h dark photoperiod. After 15 d, inoculated plants developed leaf spot symptoms, whereas control plants remained symptom-free. Fungal strains re-isolated from symptomatic leaves displayed morphological characteristics identical to SeF01. N. rosae has been reported to cause leaf spot on Fragaria × ananassa, Punica granatum, and Lonicera caerulea. To our knowledge, this is the first report of leaf spot caused by N. rosae on S. epigaea in China. The disease significantly reduces the value of S. epigaea, and pathogen-specific control measures are recommended.