Phytophthora infestans, the notorious pathogen of potato late blight, leads to a severe decline in potato yields and even harvest failure. We isolated 201 endophytic isolates from healthy root tissues of potatoes, among which 41 showed strong antagonistic activity against P. infestans. Further, the tolerance to stress and the potential application against potato late blight of these antagonistic isolates were tested. Most of them were extremely tolerant to stresses such as acid–alkali, temperature, UV, salt, and heavy metal stress. However, some antagonistic isolates with excellent stress tolerance might be pathogenic to potatoes. Combining the screening results, a total of 14 endophytes had excellent comprehensive performance in all the tests. In this paper, the endophyte 6-5 was selected among them for the preliminary exploration of the anti-oomycete mechanism. Analysis of the 16S rDNA sequence revealed that 6-5 had a high homology to the corresponding sequence of Bacillus velezensis (99.72%) from the NCBI database. Endophyte 6-5 significantly inhibited the mycelial growth of P. infestans, with an inhibition rate of over 90% in vitro assays, and deformed the hyphal phenotype of P. infestans. In addition, endophyte 6-5 could secrete protease and cellulase, and produce antagonistic substances with high thermal stability, which might be helpful to its antagonistic activity against P. infestans. Furthermore, it was demonstrated that 6-5 had the ability to improve the resistance of potato tubers to late blight. In short, our study described the process of isolating and screening endophytes with antagonistic activity against P. infestans from potato roots, and further explored the potential of biocontrol candidate strain 6-5 in potato late blight control.

Late blight, caused by Phytophthora infestans, is a devastating disease of potato. Our previous work illustrated that scopolamine, the main bioactive substance of Datura extract, exerts direct inhibitory effects on P. infestans, but it is unclear whether scopolamine and Datura extract can boost resistance to late blight in potato. In this study, P. infestans is used to infect scopolamine-treated potato pieces and leaves, as well as whole potatoes. We found that scopolamine-treated potato is resistant to P. infestans both in vitro and in vivo. The treatment of 4.5 g/L scopolamine reduces the lesion size of whole potato to 54% compared with the control after 20 d of the infection of P. infestans. The disease-resistant substance detection based on the kit method shows that scopolamine triggers the upregulation of polyphenoloxidase, peroxidase, superoxide dismutase activities, and H₂O₂ contents in potato tubers, and the decline of phenylalanine ammonia lyase and catalase activity. A total of 1682 significantly differentially expressed genes were detected with or without scopolamine treatment through high-throughput transcriptome sequencing and the DESeq2 software (version 1.24.0), including 705 upregulated and 977 downregulated genes. Scopolamine may affect the genes functioning in the cell wall, membrane and the plant-pathogen interaction. The addition of Datura extract could directly inhibit the mycelial growth of P. infestans on rye plate medium. In addition, P. infestans was found to be resistant to late blight in potato pieces treated with Datura extract. Datura extract can also be utilized in combination with the chemical fungicide Infinito in field experiments to lessen late blight symptoms and enhance potato yield. To our knowledge, this is the first study to detect the induction of disease resistance by scopolamine, and it also explores the feasibility of Datura extract in potato disease resistance.

Peucedanum praeruptorum is increasingly cultivated as wild resources are depleted. However, cultivated plants often contain lower levels of coumarins than wild individuals and may not meet the standards of the Chinese Pharmacopoeia. To clarify whether growth year could influence coumarin accumulation, we analyzed P. praeruptorum populations cultivated for 1–3 years using a newly developed 17-coumarin quantification method and conducted transcriptomics to characterize gene expression across growth years. The results suggest that total coumarins and major pyranocoumarins (notably praeruptorin B) increased steadily with growth years, while furanocoumarins and simple coumarins increased initially then declined. Notably, despite substantial intra-population variation in coumarin content, cultivated plants could be classified into two distinct chemotypes: chemotype A (higher praeruptorin A and praeruptorin E, lower praeruptorin B) and chemotype B (lower praeruptorin A and praeruptorin E, higher praeruptorin B, pteryxin, and qianhucoumarin D than chemotype A). Both chemotypes coexisted across all examined populations, with the proportion of chemotype B increasing with growth years. Transcriptomic profiling revealed that 3-year-old plants showed higher expression of pyranocoumarin biosynthetic genes and lower expression of genes associated with simple coumarin and furanocoumarin biosynthesis compared with 1-year-old plants. Differential expression analysis further identified key candidate genes associated with growth years and chemotypes. Together, these results demonstrate that growth year and chemotype synergistically regulate coumarin accumulation in cultivated P. praeruptorum, providing a two-dimensional framework for improving the quality of cultivated medicinal materials.

Potato late blight, caused by Phytophthora infestans, leads to a significant reduction in the yield and value of potato. Biocontrol displays great potential in the suppression of plant diseases. Diallyl trisulfide (DATS) is a well-known natural compound for biocontrol, although there is little information about it against potato late blight. In this study, DATS was found to be able to inhibit the hyphae growth of P. infestans, reduce its pathogenicity on detached potato leaves and tubers, and induce the overall resistance of potato tubers. DATS significantly increases catalase (CAT) activity of potato tubers, and it does not affect the levels of peroxidase (POD), superoxide dismutase (SOD), and malondialdehyde (MDA). The transcriptome datasets show that totals of 607 and 60 significantly differentially expressed genes (DEGs) and miRNAs (DEMs) are detected. Twenty-one negatively regulated miRNA-mRNA interaction pairs are observed in the co-expression regulatory network, which are mainly enriched in metabolic pathways, biosynthesis of secondary metabolites, and starch and sucrose metabolism based on the KEGG pathway. Our observations provide new insight into the role of DATS in biocontrol of potato late blight.