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.

Rambutan is a tropical tree and its fruit has several favorable characteristics. To understand how the color of the rambutan fruit peel develops, the transcriptome, flavonoid metabolome, and carotenoid metabolome data of two rambutan cultivars, ‘BY2’ and ‘BY7’, which show yellow and red peels at maturity, respectively, were comprehensively analyzed at three developmental stages. We identified 26 carotenoid components and 53 flavonoid components in these cultivars. Anthocyanins were the main component contributing to the red color of ‘BY7’ after reaching ripeness. The carotenoid content decreased sharply as the fruit matured. Hence, we speculated that flavonols were the main contributors to the yellow color of the ‘BY2’ peel. In total, 6805 differentially expressed genes were screened by transcriptome analysis; the majority of them were enriched in metabolic pathways and the biosynthesis of secondary metabolites. Weighted gene co-expression network analysis results revealed that in addition to MYB and bHLH, ERF, WRKY, MYB-related, and C3H were the main potential transcription factors regulating the color of the rambutan peel. In addition, we also identified 12 structural genes associated with flavonoid biosynthesis. The research findings shed light on the molecular mechanisms of color acquisition in rambutan fruit peels, laying the foundation for the quality control of rambutan and the cultivation of differently colored cultivars of rambutan.

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.

Diallyl trisulfide (DATS), a volatile natural sulfur-containing compound derived from garlic, possesses antifungal and preservative potential. However, its biocontrol efficacy against postharvest gray mold of tomato and the molecular mechanisms underlying fruit quality maintenance remain unclear. In this study, we systematically investigated the inhibitory effect of DATS fumigation on postharvest gray mold, its role in fruit quality maintenance, and the associated molecular mechanisms through in vitro antifungal assays, physiological and biochemical measurements, transcriptome sequencing, and correlation analysis. In vitro experiments showed that DATS at 50 μL L⁻¹ completely inhibited spore germination and germ tube elongation of Botrytis cinerea in a concentration-dependent manner, and disrupted spore membrane integrity (FDA-positive spores dropped from 73.4% to 2.9% at 50 μL L⁻¹). In vivo experiments demonstrated that Bc + DATS treatment completely inhibited lesion development compared to the control Bc, enhanced the activities of superoxide dismutase, catalase and peroxidase (e.g., CAT activity 2.20-fold higher than Bc on day 3), decreased malondialdehyde accumulation (0.65-fold of Bc on day 4), and delayed the declines in total soluble solids, titratable acidity, soluble sugars and vitamin C content (VC content 4.14-fold higher than Bc on day 4). Transcriptomic analysis revealed that DATS treatment up-regulated genes involved in plant hormone signal transduction, ubiquitin-mediated proteolysis, and phenylalanine metabolism, while down-regulating core MAPK kinases and histidine decarboxylase. Correlation analysis demonstrated significant associations between the expression of these pathway genes and antioxidant enzyme activities, vitamin C content, and lesion diameter. Collectively, DATS achieves effective control of postharvest gray mold and maintenance of fruit quality in tomato through direct antifungal activity, synergistic activation of hormone/MAPK signaling, reprogramming of phenylalanine metabolism, and modulation of membrane lipid homeostasis. This study provides a theoretical and practical basis for developing DATS as a green postharvest preservative to reduce food loss and ensure food safety.