Lycium barbarum L. is a characteristic agricultural crop in Ningxia. Powdery mildew is a serious fungal disease affecting Lycium barbarum. Resistance analysis of Lycium barbarum varieties is rarely reported, and comparative information on field resistance and associated anatomical and physiological responses remains limited. This study evaluated powdery mildew resistance in 26 Lycium barbarum germplasm accessions under natural field conditions over two years, compared leaf anatomical traits in eight representative accessions, and characterized early physiological responses in the genotype Ningqi-1 after inoculation. Based on the two-year mean disease index (DI), the 26 accessions were assigned to four descriptive resistance categories. Four sigmoidal equations were fitted to the observed disease-progress data; these equations were used only as descriptive curves and were not treated as independently validated predictive models. Across the eight representative accessions, the 2021 DI was negatively correlated with the number of palisade tissue layers, palisade tissue thickness, and leaf compactness, but positively correlated with spongy tissue thickness (two-tailed Pearson correlation, n = 8). In Ningqi-1, inoculation induced time-dependent changes in antioxidant-enzyme activities, malondialdehyde content, defense-related enzyme activities, lignin content, soluble protein content, and soluble sugar content during the first 48 h. The increase in malondialdehyde content suggested enhanced membrane lipid peroxidation during infection, which may reflect oxidative stress associated with powdery mildew infection. Overall, this study characterized field disease responses, candidate anatomical traits associated with DI, and early physiological responses in Ningqi-1. These findings provide preliminary information for future resistance screening, but validation in larger germplasm populations and under controlled inoculation conditions is still required.

DNA methylation is one of the earliest and most extensively studied epigenetic regulatory mechanisms. The ROS1 (Repressor of Silencing 1) gene was first discovered in Arabidopsis thaliana, and it is a DNA demethylase that can remove 5-methylcytosine from DNA, thereby affecting DNA methylation levels and gene expression. Objectives: The objective of this study was to investigate the role of ROS1 in the development and maturation of Ziziphus jujuba cv. “Dongzao” fruit. Methods: We cloned the ROS1 gene and conducted bioinformatics and expression characteristics analyses on it. Results: Three ROS1 genes, named ZjROS1-1~3, was identified, and each member protein was localized in the nucleus, cytoskeleton, chloroplast, and vacuole. The promoter contained cis-elements such as light response, plant hormone signal transduction, and stress response cis-elements, and it interacted with many proteins such as CMT, MET, and ZDP. The results of the real-time fluorescence quantitative PCR show that ZjROS1 has specific expression patterns in different tissues of Z. jujuba cv. Dongzao, and the expression of ZjROS1-2 in flowers and fruits is high. At the same time, CRISPR/Cas9 technology was used to construct a gene-editing vector for ZjROS1, which provided a basis for the subsequent genetic transformation. Conclusions: In this study, the biological function of ZjROS1 was clarified and a gene-editing vector was constructed, which provided a theoretical basis for the regulation mechanism of demethylase ZjROS1 in the fruit ripening and development of Z. jujuba cv. Dongzao.

Powdery mildew severely constrains the production of Lycium barbarum L., yet the molecular mechanisms underlying its response to infection remain poorly understood. Here, ‘Ningqi-1’ plants were inoculated with the powdery mildew pathogen and sampled at 0, 12, 24, and 48 hpi for integrated transcriptomic, proteomic, and metabolomic analyses. Quantitative PCR and CRISPR/Cas9-mediated gene editing were further used to evaluate the candidate susceptibility gene LbMLO6. Infection induced extensive molecular reprogramming, yielding 1299 differentially expressed genes with sustained changes, 75 DAPs shared across all three time points, and 127 shared differentially accumulated metabolites. These molecules were mainly enriched in plant–pathogen interaction, plant hormone signal transduction, MAPK signaling, phenylpropanoid biosynthesis, and α-linolenic acid metabolism pathways, suggesting coordinated roles for Ca²⁺ signaling, reactive oxygen species, defense-related proteins, and secondary metabolism in the host response. Integrated multi-omics analysis identified LbMLO6 as a candidate gene associated with powdery mildew susceptibility, its expression was markedly induced from 24 hpi onward. CRISPR/Cas9-edited LbMLO6 lines showed reduced fungal development compared with the control, particularly during the early stages of infection. These findings provide preliminary evidence that LbMLO6 may be associated with powdery mildew susceptibility in L. barbarum.