Late spring frost (LSF) poses a threat to temperate forest ecosystems; however, its combined effects with soil properties on triterpene glycosides in the buds of valuable shrubs are still unclear. In this study, natural Aralia elata (Miq.) Seem. populations were investigated in 15 counties in Heilongjiang and Jilin provinces in Northeast China. Buds were sampled in 3–5 cm length and used for determining triterpene glycosides (TGs) of Araloside VI, Araloside V, and 4-F8 (structural analogs) in spring of 2023. LSF in Heilongjiang showed longer days reaching 20 °C (CD20) (6.0 ± 2.5 d), LSF number (NLSF) (1.8 ± 0.5 times) and duration (DLSF) (21.5 ± 5.2 d), and days of temperature rise (DTR) (15.9 ± 3.8 d) compared to Jilin (4.4 ± 0.4 d, 1.2 ± 0.4 times, 17.4 ± 3.9 d, 12.0 ± 3.3 d, respectively). Araloside VI (0.30–0.59%) was positively driven by DLSF but negatively driven by DTR. Araloside V (0.04–0.17%) and 4-F8 (0.09–0.44%) were positively influenced by the lowest temperature, DTR, and CD20, negatively influenced by NLSF, and slightly influenced by organic matter. In LSF-prone regions, soil organic matter and nutrient availability do not need to be enriched, and soil pH should be higher than 5.7 if high TGs are the objective in A. elata buds.

Potato common scab is a soil-borne disease caused by Streptomyces spp., which affects the commodity value of potato worldwide. This study evaluated the inhibitory effect and potential mechanisms of the Bacillus velezensis TS-2 strain against Streptomyces scabies, providing a basis for developing safe and effective biocontrol agents for potato common scab. Strain TS-2 was isolated from soil adhering to the surface of healthy potato tubers. Confrontation assays, scanning electron microscopy, and pot experiments showed that strain TS-2 significantly reduced the potato common scab incidence and inhibited the mycelial growth and spore formation of S. scabies. Whole genome sequencing identified strain TS-2 as Bacillus velezensis. Transcriptome analysis showed that B. velezensis TS-2 significantly downregulated key genes involved in carbohydrate, lipid, and amino acid metabolism in S. scabies, including aceB, glyA, acd, thereby disrupting the core carbon and nitrogen energy supply network essential for pathogen growth and development. B. velezensis TS-2 also induced structural damage to the cell wall (pbpA), cell membrane (ino1) and bubble sac (gvpA), reducing environmental adaptability. Noticeable downregulation of genes in the bld–whi morphological differentiation cascade and the quorum-sensing gene afsA was observed under TS-2 stress, which correlates with suppressed hyphal maturation and sporulation of S. scabies.