This study investigates the potential role of Acrocalymma dark septate endophytic (DSE) fungi in promoting the growth of Solanum lycopersicum (tomato). Recognized as important symbionts that enhance plant growth and resilience under stress, particularly Acrocalymma species, DSE fungi were the focus of this investigation. Specifically, four stains isolated from gramineous plant roots (Acrocalymma sp. E00677, Acrocalymma vagum E00690, Acrocalymma chuxiongense E01299A, and Acrocalymma chuxiongense E01299B) were examined. Morphological characteristics were observed using three different media, confirming typical DSE traits such as dark pigmentation and septate hyphae. Phylogenetic analysis using six genetic markers (ITS, LSU, SSU, tef1, rpb2, and tub2) placed the strains within the Acrocalymma genus. Co-culture test and physiological index measurements showed that all strains significantly enhanced root development, as evidenced by an increased root-to-shoot ratio and a higher number of lateral roots. Additionally, the Acrocalymma DSE strains elevated chlorophyll a, chlorophyll b, and total chlorophyll content, suggesting improved photosynthetic efficiency. Anthocyanin levels were also increased in the tomato leaves, indicating enhanced antioxidative defense mechanisms. Among these strains, Acrocalymma vagum E00690 exhibited the most substantial effect on root activity. The widespread presence of 325 Acrocalymma isolates from 25 countries underscores its broad ecological adaptability. These findings suggest that Acrocalymma DSE fungi positively influence tomato growth, with potential implications for improving plant resilience under environmental stress. This study highlights the importance of further exploring DSEs, particularly Acrocalymma fungi, to better understand their ecological roles in agricultural practices, particularly in tomato cultivation.

The striped flea beetle (SFB) Phyllotreta striolata (Fabricius) (Coleoptera: Chrysomelidae) is a major pest of cruciferous vegetables in southern China. The population diversity and genetic structure of SFB are unknown. Here, we assembled a draft genome for the SFB and characterized the distribution of microsatellites. Then, we developed 12 novel microsatellite markers across the genome. We used a segment of the cox1 gene and newly developed microsatellite markers to genotype the genetic diversity of SFB across southern China. There were 44 mitochondrial haplotypes in the SFB populations, with haplotype 2 as the most widespread. The population genetic differentiation was very low, indicated by F_ST-values (<0.05 except for Guangxi population with other populations based on cox1), high gene flow (4.10 and 44.88 of cox1 and microsatellite, respectively) and Principal Coordinate Analysis across all populations. Mantel test showed genetic distance in SFB was significantly associated with geographic distance based on microsatellites (R² = 0.2373, P = 0.014) while result based on cox1 (R² = 0.0365, P = 0.155) showed no significant difference. The phylogenetic analysis did not find any geographically related clades among all haplotypes. Analyses based on microsatellites showed a lack of population genetic structure among all populations. Our study provides a foundation for the future understanding of the ecology and evolution of SFB and its management.

Tomato pith necrosis (TPN) is a highly destructive disease caused by species of the Pseudomonas genus and other bacteria, resulting in a significant reduction in tomato yield. Members of the genus Bacillus are beneficial microorganisms extensively studied in the rhizosphere. However, in most cases, the potential of Bacillus members in controlling TPN and their impact on the rhizosphere microbial composition remain rarely studied. In this study, Bacillus velezensis ZN-S10 significantly inhibited the growth of Pseudomonas viridiflava ZJUP0398-2, and ZN-S10 controlled TPN with control efficacies of 60.31%. P. viridiflava ZJUP0398-2 significantly altered the richness and diversity of the tomato rhizobacterial community, but pre-inoculation with ZN-S10 mitigated these changes. The correlation analysis revealed that ZN-S10 maybe inhibits the growth of nitrogen-fixing bacteria and recruits beneficial bacterial communities associated with disease resistance, thereby suppressing the occurrence of diseases. In summary, the comparative analysis of the rhizosphere microbiome was conducted to explore the impact of ZN-S10 on the composition of rhizosphere microorganisms in the presence of pathogenic bacteria, aiming to provide insights for further research and the development of scientific and eco-friendly control strategies for this disease.

In June 2023, a sudden outbreak root rot and vine decline symptoms was observed during a watermelon (Citrullus lanatus T.) variety demonstration trial located in Taizhou City, Zhejiang Province, China, with an incidence rate ranging from 75% to 100% and an affected area of nearly 2,000 square meters. The disease initially appeared with a rapid and alarming invasion of root rot and vine decline symptoms within watermelon plants. Affected plants exhibited rapid deterioration, showing symptoms of wilting, yellowing and eventual demise, predominantly during the pre-harvest stage. Notably, numerous black, spherical, erumpent perithecia were clearly visible on the watermelon's root epidermis, a characteristic trait of the disease. Symptomatic plant samples were rigorously disinfected with 75% ethanol, and plated on potato dextrose agar medium for incubation at 25°C, successfully isolate two potential strains. These isolates were inoculated in oatmeal agar and incubated in a 25℃ light incubator. After 30 days, mature perithecia, the same as those found on the watermelon's root epidermis, reached a diameter of 500 μm. Each perithecium contained several pear-shaped asci, 56 to 108.5 μm in length and 30.5 to 46.4 μm in width, typically holding 1, rarely 2 ascospores. These characteristics align precisely with the typical strains of Monosporascus cannonballus Pollack and Uecker (1974). Additionally, sequencing the internal transcribed spacer region of ribosomal DNA (ITS) gene (White et al., 1990), large subunit ribosomal RNA (LSU) gene (Rehner and Samuels 1995), and beta-tubulin (TUB) gene (Glass and Donaldson, 1995) were performed. BLAST analysis indicated the highest nucleotide sequence identity with M. cannonballus CBS 586.93 reference sequence (ITS: 100%, JQ771930; TUB: 98.99%, JQ907292). Representative sequences of isolate ZJUP0990-2 from these regions were deposited in GenBank (Accession No.: OR357656 for ITS; OR474500 for LSU; OR365762 for TUB). A multigene phylogenomic analysis (ITS-LSU-TUB) was undertaken to ascertain the exact phylogenetic position of M. cannonballus within the genus Monosporascus. The amalgamation of both morphological and molecular insights consistently reaffirmed the accurate classification of the causative agent as M. cannonballus. To validate the pathogenicity of M. cannonballus, a controlled greenhouse experiment was conducted using watermelon (cv. Nabite) as the subject. Mycelium fragments, harvested from the edge of the colony ZJUP0990-2, were inoculated into oat liquid medium and cultivated under dark conditions at a consistent temperature of 30°C for 7 days. After 20 days, the inoculated plants exhibited root rot and wilting, mirroring the symptoms observed during the field outbreak. In contrast, the control plants did not exhibit any signs of disease. M. cannonballus was successfully re-isolated from the symptomatic roots of the inoculated plants, satisfying Koch's postulates. This experiment was repeated three times. This pathogenic fungus has previously been documented as a menace to melons in various regions including Mexico (Chew-Madinaveitia et al., 2012) and Brazil (Sales et al., 2004), as well as watermelons in Brazil (Sales et al., 2010), northern Mexico (Gaytan-Mascorro et al., 2012), and Saudi Arabia (Karlatti et al., 1997). To our knowledge, this is the first reported presence of M. cannonballus on watermelons in China. This new disease poses a serious threat to watermelon production, potentially leading to severe economic losses and impacting food security.

Paddy–upland rotation systems are widely adopted to mitigate soil degradation in rice-based agroecosystems; however, their impacts on soil biota remain insufficiently understood. This study investigated the impacts of paddy continuous cropping (PA), upland continuous cropping (UP), and rice–loofah paddy–upland rotation (RO) on soil nematodes and microbial communities in southeastern China. Soil samples were collected prior to harvest at the end of the rice season and were analyzed for physicochemical properties, nematode communities via morphological identification, and microbial communities through high-throughput sequencing. The results showed that the RO system significantly increased soil pH, total phosphorus, available potassium, and available phosphorus, while reducing the abundance of the plant-parasitic nematode Hirschmanniella compared to the PA system. The total nematode abundance was highest in the UP system, where bacterivores predominated; the RO system was characterized by a higher proportion of algivores associated with flooded conditions, whereas the PA system was dominated by herbivores. The RO and PA system also improved nematode food web stability under flooded conditions, as indicated by higher maturity and structure indices relative to the UP system. Although microbial diversity did not differ significantly between systems, the community composition and predicted functional groups varied considerably. The relative abundance of Gemmatimonadota was significantly reduced in the PA system, while the abundance of Nitrospirota, Myxococcota, and Entorrhizomycota increased. Functional prediction revealed system-specific enrichment of bacterial metabolic groups associated with nitrogen cycling, carbon turnover, and redox-sensitive energy metabolism. Integration of soil physicochemical and biological indicators into a Soil Quality Index (SQI) ranked RO highest, underscoring its capacity to enhance soil ecological function and sustainability in rice-based systems.