Many members of the WRKY family regulate plant growth and development. Recent studies have shown that members of the WRKY family, specifically WRKY13, play various roles in the regulation of plant stress resistance. To study the function of WRKY family members in peony, the PlWRKY13 gene (KY271095) was cloned from peony leaves. Sequence analysis and subcellular localization results revealed that PlWRKY13 has no introns, belongs to the type IIc subgroup of the WRKY family, and functions in the nucleus. The expression pattern of PlWRKY13 was analysed via real-time quantitative RT-PCR (qRT-PCR), which showed that the expression of PlWRKY13 was induced by four types of abiotic stress, low-temperature, high-temperature, waterlogging and salt stress, and was positively upregulated in response to these stresses. In addition, the expression of PlWRKY13 tended to first decrease and then increase after infection with Alternaria tenuissima. Virus-induced gene silencing (VIGS) technology was used to explore the function of PlWRKY13 in the resistance of Paeonia lactiflora to fungal infection further, and the results showed that PlWRKY13-silenced plants displayed increased sensitivity to A. tenuissima. The infection was more severe and the disease index (DI) significantly greater in the PlWRKY13-silenced plants than in the control plants, and the expression of pathogenesis-related (PR) genes was also significantly altered in the PlWRKY13-silenced plants compared with the control plants. The contents of the endogenous hormones jasmonic acid (JA) and salicylic acid (SA) were measured, and the results showed that the JA content increased gradually after infection with A. tenuissima and that JA may play an active role in the resistance of P. lactiflora to pathogen infection, while the SA content decreased after PlWRKY13 silencing. The contents of the two hormones decreased overall, suggesting that they are related to the transcription of PlWRKY13 and that PlWRKY13 may be involved in the disease-resistance pathway mediated by JA and SA. In summary, the results of our study showed that PlWRKY13 expression was induced by stress and had a positive effect on the resistance of P. lactiflora to fungal infection.

Screening waterlogging-tolerant woody plants is essential for urban greening, and predictive models based on physiological indicators offer an efficient approach for rapid selection. In this study, 27 woody plant species were subjected to 10 and 15 days of waterlogging stress. Chlorophyll fluorescence parameters and biomass-related traits were measured and subsequently analyzed using linear mixed models, principal component analysis, clustering, correlation analysis, and random forest modeling. The results were as follows: (1) Waterlogging significantly suppressed most photosynthetic and biomass-related traits, whereas initial fluorescence (Fo) and dry matter content (DMC) increased; the stress response of maximum photochemical efficiency of PSII (Fv/Fm) intensified with prolonged waterlogging. (2) The first four principal components explained 83.2% of total variance, with stressed and control groups separating distinctly along PC1, reflecting photochemical inhibition. (3) Based on post-recovery phenotypes and survival rates, the 27 species were classified into strong and weak recovery capability categories; physiological clustering showed strong concordance with these recovery categories (Cramér’s V = 0.714, accuracy = 85.2%). Representative strong-recovery species included Fraxinus chinensis, Ulmus pumila, and Lagerstroemia indica, which maintained high survival (≥80%) and good ornamental quality after recovery. In contrast, representative weak-recovery species such as Kerria japonica, Syringa oblata, and Forsythia suspensa displayed marked post-recovery deterioration despite relatively intact stress-period phenotypes. (4) Among the measured parameters, maximum fluorescence (Fm) emerged as the most robust indicator, maintaining significant associations with recovery-phase phenotypes and survival in both contemporaneous and cross-period analyses (cross-period r = 0.46 with survival). Other fluorescence parameters exhibited distinct time-dependent indicative patterns. (5) Random forest models achieved the best predictive performance for 15-day survival (R² = 0.712), substantially outperforming 10-day models (R² = 0.153). Collectively, these findings demonstrate that chlorophyll fluorescence and biomass-related indicators effectively capture post-waterlogging recovery capability in woody plants, and the random forest framework provides technical support for rapid screening of waterlogging-tolerant germplasm.

Ginkgo biloba is a dioecious species valued for landscaping and medicine, but rapid sex identification outside the flowering and fruiting stages remains challenging. Hyperspectral imaging offers a potential solution, though whether spectral sex markers are stable across phenological stages and can support a single year-round model is unclear. Here, leaf hyperspectral reflectance (400–1000 nm) was acquired from mature G. biloba at flowering (n = 360), green-leaf (n = 1395), and yellow-leaf (n = 243) stages. Sex identification models were built using multiple machine learning classifiers, with leaf flavonoid content as biochemical validation. Stage-specific models achieved optimal test accuracies of 96.67% (flowering, MSC + PLS-DA), 95.77% (green-leaf, raw spectra + LDA), and 97.12% (yellow-leaf, MSC + LDA). However, discriminative bands shifted from the visible (520–690 nm) at the green-leaf stage to the near-infrared (700–1000 nm) at the yellow-leaf stage, with almost no bands shared across all stages. Furthermore, cross-stage prediction accuracy dropped to near-chance levels (~50%). As t-SNE analysis revealed, the universal model had learned phenological rather than sex-specific information. In addition, flavonoid measurements revealed a highly significant sex × stage interaction (p < 0.001) and a reversal of the sex difference between green-leaf (male > female) and yellow-leaf (female > male) stages. Thus, the spectral and biochemical sex markers examined in this study varied substantially with phenology, and stage-specific models are required for practical sex identification in G. biloba.