Fusarium wilt of Momordica charantia in the greenhouse is one of the most severe crop diseases in Shandong Province, P.R. China. This study aimed to investigate the mechanisms of accumulation and long-term survival of the pathogen in naturally pathogenic soils. Soil physicochemical properties were tested after applying a highly virulent strain of Fusarium wilt to M. charantia in an artificial disease nursery. The functional structure of soil microorganisms was analyzed through amplicon sequencing. The highly virulent strain SG−15 of F. oxysporum f. sp. momordicae was found to cause Fusarium wilt in M. charantia in Shandong Province. The strain SG−15 could not infect 14 non-host crops, including Solanum melongena and Lycopersicon esculentum, but it had varying degrees of pathogenicity towards 11 M. charantia varieties. In the artificial disease nursery for Fusarium wilt of M. charantia, the F. oxysporum was distributed in the soil to a depth of 0–40 cm and was mainly distributed in crop residues at 0–10 cm depth. During crop growth, F. oxysporum primarily grows and reproduces in susceptible host plants, rather than disease-resistant hosts and non-host crops. The colonization of the pathogen of Fusarium wilt significantly changed the soil physicochemical properties, the functional structure of soil microorganisms and the circulation of soil elements such as carbon, nitrogen, phosphorus and sulfur. Soil pH value, organic matter content, available iron content, available manganese content, FDA hydrolase activity and polyphenol oxidase activity were significantly correlated with the relative abundance of Fusarium wilt pathogens in the soil. In general, this study suggests that susceptible host plants facilitate the accumulation of Fusarium wilt pathogens in the soil. These pathogens can mediate the decomposition process of plant residues, particularly those of diseased plants, and indirectly or directly affect soil’s chemical properties.

Pine wilt disease, caused by Bursaphelenchus xylophilus (Steiner & Buhrer, 1934) Nickle 1981, poses a significant threat to the safety of pine forests in the world. Currently, the available nematicides for controlling this disease are limited. Finding new nematicides is crucial for the effective prevention and control of pine wilt disease. In this study, we discovered that tetramycin B₃, derived from Streptomyces ahygroscopicus, demonstrated a promising effect on pine wilt disease. The LC₅₀ values of tetramycin B₃ at 24, 48, and 72 h were 26.49, 23.37, and 12.79 μg/mL, respectively. Tetramycin B₃ significantly inhibited the feeding and growth rate of B. xylophilus at low concentrations while also increasing ROS (reactive oxygen species) production and lipid accumulation. Furthermore, tetramycin B₃ markedly inhibited the activity of detoxifying and protective enzymes. Transcriptome and metabolome analyses indicated that tetramycin B₃ significantly affected the expression of genes related to lysosomes, autophagy, and lipid metabolism in B. xylophilus. Additionally, tetramycin B₃ delayed the onset of pine wilt disease. Transcriptome results showed that tetramycin B₃ significantly influenced the expression of genes related to defense responses in pine trees and induced pine trees to produce disease-resistant mechanisms. Future research will focus on further elucidating the mechanism of action of tetramycin B₃ against B. xylophilus and verifying the gene functions identified through transcriptome screening.

Bursaphelenchus xylophilus (PWN), a highly destructive invasive forest pest, has expanded northward in China, even colonizing cold regions, implying evolved low-temperature tolerance. To explore its cold adaptation mechanisms, we selected PWN isolates from diverse origins, screened cold-tolerant strains via low-temperature stress assays, and conducted integrative transcriptomic and metabolomic analyses. We also compared invasive and native populations to clarify adaptive pattern differentiation. The results showed that northern Chinese isolates had significantly higher survival rates, with cold tolerance closely linked to lysophosphatidylethanolamine (LysoPE). Silencing the LysoPE-related gene BX02G0260 markedly elevated nematode mortality under low temperatures. Unlike native populations, invasive PWN may have developed a cold adaptation strategy centered on genetic material protection, with xanthosine as a key metabolite. These findings provide critical molecular insights into invasive species’ rapid cold adaptation in novel environments.