Salinity stress is a major abiotic factor that adversely affects plant growth and development. This study investigated the physiological and molecular responses of Brassica rapa L. ssp. Pekinensis to salinity stress by subjecting seedlings to varying concentrations of NaCl. Physiological analysis revealed significant wilting, chlorosis, and a marked reduction in chlorophyll and carotenoid contents in NaCl-treated seedlings, indicating impaired photosynthetic efficiency and oxidative stress mitigation. RNA-seq analysis identified extensive transcriptional reprogramming, with 6693 and 10,280 differentially expressed genes (DEGs) in Z150 and Z300 treatments, respectively, compared to the control group. DEGs were clustered into six expression trends, with sustained up-regulation in Clusters 2 and 6 and down-regulation in Cluster 3. Gene Ontology (GO) enrichment analysis highlighted the involvement of these DEGs in stress responses. Key DEGs encoding heat shock proteins, peroxidases, glutathione S-transferases, and transcription factors were significantly induced under salinity stress, suggesting their roles in stress adaptation. Furthermore, GO and KEGG enrichment analyses revealed significant down-regulation of genes associated with photosynthesis and carbon metabolism, indicating disruption of these critical pathways. Weighted Gene Co-expression Network Analysis (WGCNA) identified hub genes, such as histidine synthase and low-density receptor-like protein, potentially central to salinity stress responses. Additionally, carotenoid metabolism was significantly inhibited, with down-regulation of key genes in the carotenoid biosynthesis pathway. RT-qPCR validation confirmed the reliability of the RNA-seq data. Collectively, these findings provide comprehensive insights into the physiological and molecular mechanisms underlying response of B. rapa L. ssp. Pekinensis to salinity stress, highlighting potential targets for improving salinity tolerance in crops.

The abscission of plant organs plays an important role in ensuring the normal life activities. Rose is one of the most important ornamental plants, and its premature abscission of petal has seriously affected the quality and commercial value. Silver Thiosulfate (STS) is an ethylene inhibitor, which is often used preservative to delay the senescence of fresh cut flowers. To understand the regulatory mechanism of petal abscission in rose by STS, integrative analysis of the metabolome and transcriptome profiles was performed in abscission zone (AZ) tissues of rose under different treatments (MOCK, STS, ETH, STS+ETH). The results showed that STS significantly delayed the petal abscission in phenotype and reduced the activity of two enzymes (pectinase and cellulase) associated with cell wall degradation in physiological level. STS affected the contents of five metabolites (shikonin, jasmonic acid, gluconolactone, stachyose and D-Erythrose 4-phosphate), and involved changes in the expression of 39 differentially expressed genes (DEGs) associated with these five metabolites. Five DEGs (LOC112192149, LOC112196726, LOC112189737, LOC112188495, and LOC112188936) were probably directly associated with the biosynthesis of shikonin, jasmonic acid, and D-Erythrose 4-phosphate. Meanwhile, the effect of STS on the abscission process significantly involved in the pentose phosphate pathway and amino acid biosynthesis pathway. In addition, STS had a greater effect on the transcription factors, phytohormone related DEGs represented by auxin and ethylene, DEGs related to disease resistance and amino acid, etc. Above all, STS negatively influences petal abscission of rose, these results maybe provide a reference for subsequent studies on petal abscission of rose by STS.

Petal abscission affects the growth, development, and economic value of plants, but the mechanism of ethylene-ROS-induced petal abscission is not clear. Therefore, we treated roses with different treatments (MOCK, ETH, STS, and ETH + STS), and phenotypic characteristics of petal abscission, changed ratio of fresh weight, morphology of cells in AZ and the expression of RhSUC2 were analyzed. On this basis, we measured reactive oxygen species (ROS) content in petals and AZ cells of roses, and analyzed the expression levels of some genes related to ROS production and ROS scavenging. Ethylene promoted the petal abscission of rose through decreasing the fresh weight of the flower, promoting the stacking and stratification of AZ cells, and repressing the expression of RhSUC2. During this process, ethylene induced the ROS accumulation of AZ cells and petals mainly through increasing the expressions of some genes (RhRHS17, RhIDH1, RhIDH-III, RhERS, RhPBL32, RhFRS5, RhRAC5, RhRBOHD, RhRBOHC, and RhPLATZ9) related to ROS production and repressing those genes (RhCCR4, RhUBC30, RhSOD1, RhAPX6.1, and RhCATA) related to ROS scavenging. In summary, ROS and related regulatory factors involved in ethylene induced petal abscission in roses.