Bacterial blight caused by Pseudomonas syringae pv. glycinea (Psg) is a widespread foliar disease. Although four Resistance to Pseudomonas syringae pv. glycinea (Rpg) 1 to 4 (Rpg1∼4) genes that have been observed to segregate in a Mendelian pattern have been reported to confer resistance to Psg in soybean, the genetic basis of quantitative resistance to bacterial blight in soybean remains unclear. In the present study, the Psg resistance of two soybean association panels consisting of 573 and 213 lines, respectively, was phenotyped in multiple environments in 2014 to 2016. Genome-wide association study was performed using two models, FarmCPU and BLINK, to identify Psg resistance loci. A total of 40 soybean varieties with high level of Psg resistance were identified, and 14 quantitative trait loci (QTLs) were detected on 12 soybean chromosomes. These QTLs were identified for the first time. The majority of the QTLs were detected only in one or the other association panels, while qRPG-18-1 was detected in both association panels for at least one growing season. A total of 46 candidate Psg resistance genes were identified from the qRpg_13_1, qRPG-15-1, and qRPG-18-1 loci based on gene function annotation. In addition, we found the genomic region covering rpg1-b and rpg1-r harbored the synteny with a genomic region on chromosome 15 and identified 16 nucleotide binding site–leucine-rich repeat (NBS-LRR) genes as the candidate Psg resistance genes from the synteny blocks. This study provides new information for dissecting the genetic control of Psg resistance in soybean.

Quantitative real-time PCR (qRT-PCR) is a dominant technique for gene expression analysis in medicinal plants, and accurate qRT-PCR data normalization strictly relies on stably expressed reference genes (RGs). However, systematically validated RGs for Panax quinquefolius L. across diverse tissues, abiotic stresses, and hormone treatments are still lacking. In this study, 15 candidate RGs with FPKM values ranging from 7.21 to 210.56 were selected from RNA-Seq datasets based on expression abundance, coefficient of variation, and homology to commonly used reference genes. The expression stability of candidate RGs was evaluated under tissue-specific, drought, waterlogging, gibberellin A3 (GA3), and melatonin (MT) treatments using ΔCt, geNorm, NormFinder, BestKeeper, and RefFinder methods. UBC28 and EF1-α ranked as the top two most stable reference genes across all tested conditions, with stability values of 2.21 and 2.38, respectively. Subsequent qRT-PCR validation of eight ginsenoside biosynthesis-related genes using the UBC28 and EF1-α normalization system showed that drought and waterlogging stresses induced significant expression fold changes (1.5–4.8-fold) in most ginsenoside synthetic genes, while exogenous GA3 and melatonin treatments caused no significant transcriptional regulatory effects under the tested experimental conditions. This study provides a set of reliable, condition-adaptive RGs for P. quinquefolius and establishes a robust molecular tool for future studies on ginsenoside biosynthesis and stress response mechanisms in American ginseng.

Panaxadiol (PD) is a bioactive dammarane triterpenoid with limited antiproliferative potency, and systematic optimization of its C3 and C12 positions remains underexplored. Here, a stepwise, site-differentiated strategy was established by combining selective C3 esterification with late-stage C12 diversification through a chloroacetyl–piperazine linker, affording 23 PD derivatives and enabling complementary C3/C12 structure–activity analysis. Antiproliferative screening in AGS gastric cancer cells identified compounds 6, 11, and 17 as the most active analogues, with IC₅₀ values of 8.41, 5.08, and 6.78 μM, respectively, all outperforming 5-fluorouracil under identical conditions. Compound 6 provided a relatively favorable balance between low-micromolar activity and preservation of non-malignant GES-1 cells within a defined concentration range and was therefore selected for mechanistic investigation. Transcriptomic profiling identified 298 differentially expressed genes associated with cellular stress, cytokine signaling, epithelial growth regulation, and extracellular remodeling, whereas metabolomic analysis revealed marked perturbation of glycerophospholipid, choline, polyunsaturated fatty acid, and glutathione metabolism. Integrated analysis highlighted membrane-lipid remodeling, redox dysregulation, and ferroptosis-related processes as central features of the response. These findings establish a modular platform for PD optimization and identify compound 6 as a promising lead for further anti-gastric cancer development.