Plastics are extensively applied in agricultural production, and exposure of crops to micro- and nano-plastics (MNPs) can markedly affect crop health. However, current understanding of the effects of particle size and concentration on the physiological and biochemical responses of plants remains limited. In this study, the effects of polyethylene micro-plastics (2 μm) and nano-plastics (200 nm) at varying concentrations in cherry radish were investigated. Plant biomass, physiological and biochemical responses, and the microspatial distribution and transport behavior of organic components at the soil-root interface were evaluated. The results demonstrated that high concentrations (150 mg/kg) of both micro- and nano-sized plastic particles significantly inhibited plant growth and photosynthetic performance, including reductions in chlorophyll content, net photosynthetic rate, and stomatal conductance. Notably, stress resistance indicators, such as soluble protein and soluble sugar, were affected, particularly at higher concentrations. SEM analysis directly verified the attachment of micro-plastic particles to root surfaces, whereas nano-particles were capable of penetrating root tissues. Synchrotron radiation-based FTIR imaging enabled in situ visualization of functional group distributions within the soil-root microenvironment, and semi-quantitative analysis further revealed a significant increase in carboxylic functional groups under nanoscale plastic exposure. This study also proposed a novel strategy to characterize the distribution and interactions of organic components within plant roots under MNP-induced stress. Overall, these findings offer new insights into the biological impacts and translocation potential of MNPs in crops, emphasizing their potential risks to agricultural production.

Cucumber (Cucumis sativus L.) is an important vegetable. China's annual output exceeds 50 million tons, accounting for more than 40% of the world total. In Nov 2021, a wilt disease was observed on cucumber plants in Beiluo Town, Shouguang, Weifang City, Shandong Province, China (36°88'N, 118°74'E). The incidence across the greenhouses (≈0.13 ha) was approximately 25%. Leaves of plants in the field turned yellow and wilted. Finally, the whole plant withered and died. The base of the main vine stem shrank and the epidermis cracked longitudinally. Tissue fragments from infected stem bases (5 mm × 5 mm) were surface disinfected with 0.1% mercuric chloride solution for 30 s, followed by 75% ethanol for 30 s, and then washed three times with ddH₂O. These sections were then placed onto PDA and incubated at 25 ± 2°C for five days. Twelve strains (similar colony morphology) belonging to fungal species were obtained from 10 disease samples. On PDA, the colonies appeared off-white or light-orange, occasionally with radiating wrinkles, a damp surface, and defined margins. The conidiophores were solitary, unbranched or rarely irregularly branched, transparent, smooth-surfaced, and thin-walled. Sporulation cells (bottle-stem type autotrophic hyphae) extended with a transparent, smooth surface, a slightly wider base, and a pointed top. Typically, they were solitary upright bottle-necks, 6.3-24.3 μm × 1.4-3.3 μm (n = 30). The conidia aggregated into a head-shaped, oval, shaped, or round shape with narrow ends and a wide middle, transparent, smooth-surfaced, with thin walls and 0-1 septa, containing oil globules. The size of conidia ranged from 4.0-8.9 μm × 2.0-4.0 μm. These morphological characteristics were similar to those of Plectosphaerella sp. At the same time, the internal transcriptional spacer (ITS), and the large subunit (LSU) of the 28S rRNA gene were amplified and sequenced using the primer pairs ITS1/ITS4 and LR5/LROR (Giraldo et al., 2019). BLASTn analysis, the obtained sequences of the ITS amplicon (OR994322), and the LSU domain amplicon (PP092994) showed 99.80% (507/508 bp) and 97.21% (872/897 bp) identity to sequences of P. cucumerina isolates OP881967.1 and MK143394.1, respectively, in the NCBI database. A multilocus phylogenetic tree constructed by MEGA 11 software showed that the representative isolates were assigned to the group of P. cucumerina. To confirm their pathogenicity, 10 ml of spore suspension (105 spores/ml) were poured onto the rhizomes of seedlings (1-2 leaf stage; 20 plants per strain). Another 20 seedlings treated with sterile distilled water were used as the control. Each trial was performed three times. Seedlings inoculated with P. cucumerina began to show symptoms on the 5th day, which continued until the 21st day after inoculation. The symptoms were similar to those observed in the diseased plants in the field. The control seedlings showed no symptoms. P. cucumerina was re-isolated from inoculated diseased seedlings with 100% homology, whereas no fungal growth was observed from the control seedlings. The results indicate that P. cucumerina was the pathogen of cucumber blight. So far, More than 10 species of plants, including Brassica oleracea and Foeniculum vulgare, are known hosts of P. cucumerina in China (Li et al.2017, Su, et al. 2017). This is the first report of P. cucumerina causing wilt on C. sativus L. (Lei et al., 2017). Our study laid a critical foundation for the prevention and control of this disease on cucumbers in China.

Stemphylium lycopersici is the causal pathogen of the devastating tomato gray leaf spot with a wide range of alternative plant hosts. To mitigate its potential endemic in facility-cultivated tomatoes, novel disease control strategies should be attempted to minimize the use of chemical fungicides. In this study, we identified a metalloprotease from S. lycopersici genome and designated it as SlMEP1, as it appears to be a typical zinc metalloproteinase containing a WLM (WSS1-like metalloprotease) domain and a characteristic HEXXH motif, which we determined by analyzing its transcriptional profile and enzymatic functions. The transcription level of SlMEP1 increased greatly during the fungal invasion of tomato leaves. The deletion of the SlMEP1 gene from S. lycopersici hindered its mycelial growth and reduced its pathogenicity. An assessment of the functional dissection indicated that SlMEP1 induced cell collapse and inhibited the expression of the host chitinases, which consequently made tomato cells more susceptible to S. lycopersici and other pathogenic fungi.

Hawthorn (Crataegus pinnatifida) is an important economic fruit and Chinese medicinal plant, which is widely distributed in the northern China. In early July 2024, a fruit rot disease was observed on the young fruits of hawthorn in a park of Shouguang, Shandong Province, China (36°53'42.16″N, 118°47'22.4″E). Forty plants were surveyed (from approximately 120 trees), which had 15 to 30% of fruits infected. Diseased fruits displayed brown, sunken, approximately circular lesions. Small sections (3-4 mm) cut from the edges between the diseased and healthy tissue from 20 diseased fruits were surface sterilized by using 75% ethanol for 30 s, and rinsed thrice with sterile distilled water. The diseased tissues were then dried and plated onto potato dextrose agar (PDA) and incubated at 25°C in the dark. Cultures were purified by hyphal tipping. In total, 12 colonies were isolated from the necrotic tissues, and all of them showed similar morphological characteristics. The colonies were initially white, gradually turning gray-green to dark gray after 5 days. Conidia were hyaline, aseptate, ellipsoidal to obovoid, 20.1-29.3 × 5.0-8.3 μm, with an average of 24.2 × 6.6 μm (n = 30). These morphological traits suggested that the pathogen shares similarities with the Botryosphaeria dothidea (Zhang, et al., 2021). For accurate identification, three representative isolates (SGSZ-01 to SGSZ-03) were selected for molecular identification by amplifying and sequencing the internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (TEF1-α), and β-tubulin (TUB2) with the primers ITS1/ITS4, EF1-728F/986R, and Bt2a/Bt2b (Carbone and Kohn 1999; Jia et al. 2019), respectively. GenBank accession numbers were PQ197601, PQ586368, and PQ586369 for ITS, PQ201924, PQ588676, and PQ588677 for TEF1-α, and PQ201925, PQ588678, and PQ588679 for TUB2, and gene sequencing showed 99.2 to 100% identity with the ex-type strain of B. dothidea (CMW 8000). Results from the maximum likelihood phylogenetic analysis, based on the three concatenated gene sequences, placed our isolates in a clade with B. dothidea. The pathogenicity of SGSZ-01 was conducted using a wound inoculation method on 11-week-old fruits of 10-year-old hawthorn trees both on living plants and detached fruits. All fruits were wounded with a sterilized needle and inoculated by placing 5 mm² agar plugs of 5-day-old cultures grown on PDA. Control fruits were treated with agar plugs. All the attached fruits were enclosed in a plastic bag with a wet cotton ball for 5 days. The same number of detached inoculated fruits were placed in Petri dishes on a piece of wet filter paper and incubated at 25°C. The pathogenicity test was conducted three times independently. Necrotic lesions (4.5 ± 0.3 mm in diameter) resembling natural infections were observed on fruits 7 days after inoculation, and no symptoms appeared on the control fruits. The pathogen was reisolated from the lesions and was identified by the methods described above. No pathogens were isolated from control fruits. Therefore, the pathogen of hawthorn fruit rot in China is B. dothidea. B. dothidea has previously been reported causing fruit rot on mango, plum, pomegranate fruit, and apple in China (Feng et al. 2023; Gu et al. 2020; Tang et al. 2012; Yuan et al. 2024). To our knowledge, this is the first report of B. dothidea causing fruit rot disease on C. pinnatifida. The information on identification of this fungus may be helpful to the control and prevention of the disease.

Euonymus fortunei (Turcz.) Hand.-Maz., an evergreen vine shrub, commonly used for landscaping and herbaceous medicines in China. In December 2024, leaf spot symptoms were noticed on E. fortunei plants in three parks with a 15-25% disease incidence out of 160 trees in Weifang City, Shandong Province in China (118°44'34.9''E, 36°52'17.3''N). Irregularly shaped lesions with a grayish-white center and brownish margins surrounded by a yellow halo developed on infected leaves and coalesced at later stages. To isolate the causal agent, 14 diseased leaves were randomly collected from 10 trees in different parks and a small piece (2 x 2 mm) was sliced from each lesion at the edge, surface-disinfected with 75% ethanol for 30 s, rinsed 3 times in sterilized water, placed on a potato dextrose agar (PDA), and incubated at 27°C in the dark for 3 days. Botryosphaeria sp.-like fungal colonies were isolated from 93% of the sampling plates and 3 representative fungal isolates (FFT01 to FFT03) were selected randomly for morphological and molecular characterization and hyphal-tip purified. Fungal colonies initially appeared to be white with fluffy mycelia and gradually developed a grayish-black pigment. The hyaline, unicellular, and oblong-fusiform conidia were 20.1 - 25.7 μm (mean = 23.2 ± 1.4) long and 6.3 - 9.1 μm (mean = 7.2 ± 0.8) in diameter (n = 30), similar to the morphological features of Botryosphaeria dothidea (Zhang et al. 2021). The internal transcribed spacer (ITS) region, translation elongation factor 1-alpha (tef1) gene, and beta-tubulin (tub2) gene were amplified and sequenced using primer pairs ITS1/ITS4, EF1- 728F/EF1-986R, and Bt2a/Bt2b, respectively (White et al. 1990; Glass and Donaldson 1995; Carbone and Kohn 1999) and desposited in GenBank (Accession Nos. PV422744 to PV422746 for ITS, PV441492 to PV441494 for tef1, and PV4414485 to PV441487 for tub2). Sequences had > 99% identity with their corresponding sequences from the ex-type B. dothidea strain CMW 8000. In the maximum-likelihood phylogeny derived from the concatenated alignments, all three isolates were grouped in the B. dothidea clade. To validate the pathogenicity of FFT01 isolate, five leaves from each of three one-year-old E. fortunei seedlings were scratched with a sterilized syringe needle and then a 5 mm² mycelial PDA plug of 6-day-old culture was placed on each wounded site. Three E. fortunei seedlings inoculated with sterile PDA plugs served as controls. Each wound-inoculated seedling was enclosed in a transparent plastic bag for 3 days then kept in a growth chamber under controlled conditions (27°C, 14/10-h light/dark cycle, and 75% relative humidity). Seven days post-inoculation, grayish-white lesions surrounded by yellow halo were observed on leaves with black pycnidia developing in lesions, similar to the symptoms on the naturally infected leaves, while no lesions appeared on mock-inoculated leaves. The identity of the fungus re-isolated from symptomatic leaves was confirmed as B. dothidea based on morphology and DNA sequence. The pathogenicity test was repeated three times with similar results. Although B. dothidea has been reported as a common fungal pathogen causing leaf spot, fruit rot or stem canker on a variety of plants including plum, Kadsura coccinea, and soybean (Chen et al. 2021; Su et al. 2024; Yuan et al. 2024), this is the first report on its occurrence on E. fortunei in China. This study will provide a basis for the prevention and control of leaf spot on E. fortunei in the future.