Catalpa bungei is an economically important tree with high-quality wood, which is highly ornamentally valuable in China. Salinity is one of the major constraints restricting the growth of the C. bungei. However, the molecular mechanism underlying the salt stress response remains unknown in C. bungei. In our previous study, a novel WRKY transcription factor gene CbWRKY27 was isolated using association mapping based on the transcriptome database of Catalpa Yuqiu1. In this study, CbWRKY27 was found to function as a transcriptional activator in the nucleus. The transcription of CbWRKY27 was inhibited under salt stress and reactive oxygen species (ROS) but was induced after abscisic acid (ABA) treatment. CbWRKY27-overexpression plants showed decreased tolerance to salt stress compared to wild type while enhancing sensitivity to ABA-regulated lateral root length. Quantitative real-time PCR (qPCR) studies showed that the transcript levels of the ABA biosynthesis gene (NCED3), signaling genes (ABI3 and ABI5), and responsive genes (RD29B and RD22) were greatly increased in CbWRKY27-overexpression plants under salt stress. Under salt treatment, CbWRKY27-overexpression plants disturbed ROS homeostasis by repressing antioxidant enzymes and enhancing the production of O₂⁻ and H₂O₂ through down-regulation of ROS-scavenging-related genes (APX, SOD, and PER57). In summary, these results indicate that CbWRKY27 negatively regulates salt tolerance in C. bungei.

Aquaporins play a crucial role in helping water molecules move across cell membranes. While some studies have examined the role of AQPs in model plants like Arabidopsis, their impact on the ability of non-model plants to withstand environmental stress is largely unknown. In this study, we have explored the functions of the PaPIP1-2 gene, which encodes a protein called PIP, in apricot kernels (Prunus armeniaca L.). Our findings reveal how the PaPIP1-2 gene behaves during both dormancy and sprouting phases. Using a network analysis, we identified its interaction with six genes related to cold resistance. The mRNA levels of PaAQP genes, which co-express with cold resistance genes, remain consistent throughout different stages of P. armeniaca flower bud development, including physiological dormancy (PD), ecological dormancy (ED), sprouting period (SP), and germination stage (GS). Furthermore, our investigation of the location of the GFP-tagged PaPIP1-2 protein showed that it is mainly found in the cell membrane. Yeast strains with overexpressed PaPIP1-2 exhibited improved cold resistance and higher protein content. Similarly, when we overexpressed PaPIP1-2 in Arabidopsis, it enhanced the growth of these transgenic plants under cold stress. This improvement was associated with reduced levels of MDA (malondialdehyde); decreased ion leakage; increased proline accumulation; superoxide dismutase (SOD) activity; and the expression of cold resistance genes like AtPUB26, AtBTF3L, AtEBF1-1, and AtRAV1, compared with the wild-type plants. In summary, our results highlight the role of the P. armeniaca PaPIP1-2 gene in enhancing cold resistance and its importance in the dormancy and germination stages.

Background: The yellow-leaf gl1 mutant of Lagerstroemia indica exhibits an altered phenylpropanoid metabolism pathway compared to wild-type (WT). However, details on the metabolites associated with leaf color variation, including color-specific metabolites with bioactive constituents, are not fully understood. Methods: Chemical and metabolomics approaches were used to compare metabolite composition and antioxidant capacity between the gl1 mutant and WT leaves. Results: The mutant exhibited an irregular xylem structure with a significantly lower phenolic polymer lignin content and higher soluble phenolic compounds. Untargeted metabolomics analysis identified phenolic compounds, particularly lignans, as key differential metabolites between gl1 and WT, with a significant increase in the mutant. The neolignan derivative balanophonin-4-O-D-glu was identified as a characteristic metabolite in the gl1 mutant. The soluble phenolic compounds of the gl1 mutant exhibited higher FRAP, ABTS, DPPH, and hydroxyl radical scavenging activity than in WT. Correlation analysis showed a positive relationship between antioxidant capacity and phenolic compounds in L. indica. Conclusions: Metabolites associated with leaf color variation in the L. indica yellow-leaf gl1 mutant demonstrated high antioxidant capacity, particularly in scavenging hydroxyl radicals.