Mei-Li Zhao

In the autumn of 2024 and 2025, a severe outbreak of powdery mildew was observed on Zinnia elegans in Xinyang, Henan Province, central China, with disease incidence exceeding 90%. White powdery colonies appeared on adaxial leaf surfaces and later spread to stems and flowers, causing chlorosis and premature senescence. The fungus produced nipple‐shaped appressoria, straight conidiophores (75.0–200.0 × 9.0–16.0 μm) with cylindrical foot cells and ellipsoid‐ovoid conidia (18.0–30.0 × 14.0–20.0 μm), consistent with the genus Podosphaera . Although fibrosin bodies were not clearly discernible under standard bright‐field microscopy, the diagnosis was strongly supported by molecular evidence. The ITS sequence showed 100% similarity to Podosphaera xanthii representative isolates, and phylogenetic analysis placed the isolate within the P. xanthii clade (sensu lato). Pathogenicity was confirmed by fulfilling Koch's postulates. This is the first confirmed report of P. xanthii (s.l.) infecting Z. elegans in Henan Province, central China.

Potentilla indica (Andrews) Th.Wolf (syn. Duchesnea indica (Andrews) Teschem.), commonly known as Indian mock strawberry or snakeberry, is a perennial herbaceous plant belonging to the Rosaceae fam...

Sulfur metabolism and stress responses are fundamental to plant growth and seed development. ETHE1 encodes a mitochondrial sulfur dioxygenase that plays important roles in these processes; however, its function in Jatropha curcas remains unknown. In this study, we report the cloning and in silico characterization of a putative JcETHE1 gene from J. curcas. Bioinformatic analysis revealed that JcETHE1 has an open reading frame of 726 bp encoding a 241-amino-acid protein, which is predicted to localize in mitochondria and possesses a typical sulfur dioxygenase conserved domain. Because the transcript ends were not experimentally confirmed and the predicted protein is shorter than related plant homologues, the possibility that the cloned sequence is partial cannot be excluded. Phylogenetic analysis showed that JcETHE1 clusters within the Euphorbiaceae clade, showing high similarity to ETHE1 from Manihot esculenta and Hevea brasiliensis. In silico promoter analysis suggested that, in addition to core elements, the JcETHE1 promoter contains multiple putative regulatory elements associated with light response, hormone responses (ABA, ethylene, gibberellin), floral development (CArG-box, AAGAA-motif), stress responses, and endosperm development. These findings provide a molecular basis for future functional studies of JcETHE1 and suggest that it may serve as a potential candidate gene for further investigation into reproductive development and stress responses in J. curcas. However, these hypotheses require experimental validation.

Bidens pilosa L., an annual herbaceous plant with a wide distribution, possesses novel medicinal properties. In January 2021, a powdery mildew disease outbreak was documented on B. pilosa plants located in the roadside areas in Shenzhen, Guangdong Province, China, with 60 to 80% disease incidence. Initial symptoms manifested as small, irregular white powdery patches, primarily on the adaxial surfaces of leaves. Subsequently, the colonies expanded, forming coalescent colonies that spread across the leaves, petioles, and stems, eventually leading to the distortion and senescence of leaves. Hyphae are hyaline, flexuous to straight, septate, with thin walls and a width ranging from 2 to 8 μm. Hyphal appressoria are nipple-shaped. Conidophores are erect or slightly flexuous, ranging from 80 to 150 µm in length and 12 to 18 µm in width (n = 30). Typically, these conidophores bear chains of 2 to 5 immature conidia, displaying a sinuate outline. Foot-cells, located at the base of conidophores, are cylindrical and erect, approximately 33 to 100 µm in length and 6 to 10 µm in width (n = 30). Conidia are hyaline, ellipsoid-ovoid to barrel-shaped, and lack fibrosin bodies. Primary conidia are ellipsoid-ovoid in shape, characterized by a rounded apex and a subtruncate base, 25 to 40 µm × 15 to 22 µm in width. Secondary conidia are barrel-shaped with truncate or subtruncate ends, 27 to 35 µm × 15 to 20 µm in width. Germ tubes exhibit a longitubus pattern and are prominently produced at the perihilar or apical region of the conidia. No chasmothecia were observed in the collected samples. In order to conduct a molecular-level identification, mycelium and conidia were collected from B. pilosa leaves. Genomic DNA was subsequently extracted from these samples. The internal transcribed spacer (ITS), intergenic spacer (IGS) and beta-tubulin (tub2) sequences were performed using primer pairs ITS1/ITS4, IGS-12a/NS1R, and tub2, respectively (Carbone and Kohn 1999; Scholin et al. 1994; White et al.,1990). A 568-bp ITS, a 366-bp IGS, and a 354-bp tub2 sequences (GenBank accession nos. OR647592, OR978282 and OR978283) were obtained. The ITS sequence exhibited over 99.6% similarity to Golovinomyces ambrosiae (MT929773) and G. cichoracearum (MH590731). The IGS sequence displayed 100% similarity to G. ambrosiae (MK383490) and G. ambrosiae (OK349420). The tub2 sequence displayed 100% similarity to G. ambrosiae (MW981257) and G. ambrosiae (MW981256). Phylogenetic analysis of IGS, ITS and tub2 also grouped obtained sequences within the G. ambrosiae complex. Based on the analysis of morphological characteristics and sequence identity, the pathogen was identified as G. ambrosiae. In order to satisfy Koch's postulates, an infected leaf was carefully pressed onto leaves of six healthy young B. pilosa plants, each grown in a separate pot. Additionally, a control group consisted of six non-inoculated plants. All plants were placed in a greenhouse: 25°C, 14/10-h light/dark photoperiod, and relative humidity 50%. After 10 days, the inoculated leaves exhibited powdery mildew colonies similar to those observed in the original infected plants. At 16 days, the inoculated leaves exhibited discoloration and premature leaf drop. The pathogenicity test was conducted twice. Microscopic observation and sequencing confirmed that isolated fungus was identical to the original pathogen. G. ambrosiae has previously been documented on B. pilosa in Fuzhou, Fujian Province, China (Mukhtar et al., 2022). However, to the best of our knowledge, this study represents the first report of powdery mildew caused by G. ambrosiae on B. pilosa in Shenzhen, Guangdong Province, China.

Chromatin architecture is an essential factor regulating gene transcription in different cell types and developmental phases. However, studies on chromatin architecture in perennial woody plants and on the function of chromatin organization in sex determination have not been reported. Here, we produced a chromosome-scale de novo genome assembly of the woody plant Jatropha curcas with a total length of 379.5 Mb and a scaffold N50 of 30.7 Mb using Pacific Biosciences long reads combined with genome-wide chromosome conformation capture (Hi-C) technology. Based on this high-quality reference genome, we detected chromatin architecture differences between monoecious and gynoecious inflorescence buds of Jatropha. Differentially expressed genes were significantly enriched in the changed A/B compartments and topologically associated domain regions and occurred preferentially in differential contact regions between monoecious and gynoecious inflorescence buds. Twelve differentially expressed genes related to flower development or hormone synthesis displayed significantly different genomic interaction patterns in monoecious and gynoecious inflorescence buds. These results demonstrate that chromatin organization participates in the regulation of gene transcription during the process of sex differentiation in Jatropha. We have revealed the features of chromatin architecture in perennial woody plants and investigated the possible function of chromatin organization in Jatropha sex differentiation. These findings will facilitate understanding of the regulatory mechanisms of sex determination in higher plants.