Tomato yellow leaf curl virus (TYLCV) is a prominent viral pathogen that adversely affects tomato plants. Effective strategies for mitigating the impact of TYLCV include isolating tomato plants from the whitefly, which is the vector of the virus, and utilizing transgenic lines that are resistant to the virus. In our preliminary investigations, we observed that the use of growth retardants increased the rate of TYLCV infection and intensified the damage to the tomato plants, suggesting a potential involvement of gibberellic acid (GA) in the conferring of resistance to TYLCV. In this study, we employed an infectious clone of TYLCV to inoculate tomato plants, which resulted in leaf curling and growth inhibition. Remarkably, this inoculation also led to the accumulation of GA₃ and several other phytohormones. Subsequent treatment with GA₃ effectively alleviated the TYLCV-induced leaf curling and growth inhibition, reduced TYLCV abundance in the leaves, enhanced the activity of antioxidant enzymes, and lowered the reactive oxygen species (ROS) levels in the leaves. Conversely, the treatment with PP333 exacerbated TYLCV-induced leaf curling and growth suppression, increased TYLCV abundance, decreased antioxidant enzyme activity, and elevated ROS levels in the leaves. The analysis of the gene expression profiles revealed that GA₃ up-regulated the genes associated with disease resistance, such as WRKYs, NACs, MYBs, Cyt P450s, and ERFs, while it down-regulated the DELLA protein, a key agent in GA signaling. In contrast, PP333 induced gene expression changes that were the opposite of those caused by the GA₃ treatment. These findings suggest that GA plays an essential role in the tomato’s defense response against TYLCV and acts as a positive regulator of ROS scavenging and the expression of resistance-related genes.

Root-knot nematodes (RKNs) severely affect the yield and quality of vegetable crops. While some chemical pesticides can effectively eliminate RKNs, they leave behind significant pesticide residues in vegetables and soil that are potentially harmful for humans. Research suggests that dormant RKNs in the soil become active in the presence of a host, upon which they become sensitive to extreme temperature changes. Here, we tested a novel method to eliminate RKNs (Meloidogyne incognita) in a greenhouse setting. RKNs were first activated by water spinach, at which point the soil was heated by natural sunlight and suddenly cooled by the addition of dry ice. This rapid change in temperature eliminated >90% of activated RKNs. After the temperature treatment, the physical features of soil did not change; however, soil porosity, available potassium content and soil invertase activity increased markedly. The treated soil was then used for cucumber planting to test its viability. Compared with cucumber plants grown in untreated soil, plants in treated soil had higher, thicker, and stronger shoots, and higher photosynthetic ability. Cucumber plants grown in untreated soil were severely infested with nematodes while few plants grown in treated soil had root knots containing nematodes. Based on these findings, we suggest that host plant induction followed by switched temperature treatment is an effective, easy, safe, and cost-effective method for eliminating RKNs.

Blossom-end rot (BER) in tomatoes is a physiological disorder primarily caused by the disruption of calcium absorption and transport. This study cultivated tomatoes using a trough-based vermiculite system. Two treatments were established: a calcium-deficient nutrient solution and a calcium-deficient nutrient solution supplemented with 0.1 mg/L BR (n = 40 plants per treatment). The activities of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD), as well as the contents of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), were measured in the leaves. Calcium ion content was also determined in various plant parts. Statistical analysis of differences was performed using Duncan’s multiple range test at a significance level of p < 0.01. Concurrently, transcriptome sequencing of root, stem, and leaf tissues was conducted via high-throughput sequencing technology. The results showed that foliar application of BR under calcium deficiency significantly reduced the incidence of BER (from 26.67% to 6.67%) and effectively increased calcium ion content in leaves, stems, and roots. At the physiological level, BR treatment markedly enhanced the activities of CAT, POD, and SOD in leaves (by 105.70%, 117.12%, and 82.77%, respectively), while reducing H₂O₂ and MDA contents (by 36.90% and 16.38%, respectively). This indicates that BR alleviates membrane lipid peroxidation damage by enhancing the antioxidant defense system. Gene Ontology (GO) enrichment analysis revealed that the differentially expressed genes (DEGs) were primarily involved in biological processes, such as secondary metabolic processes, response to oxygen-containing compounds, and cell wall organization. KEGG pathway analysis further indicated significant enrichment in pathways, including phenylpropanoid biosynthesis, plant hormone signal transduction, and plant–pathogen interaction. Additionally, key genes, such as the cytochrome c oxidase (COX) gene (Solyc03g013460.1), exhibited a gradient up-regulation pattern (root > stem > leaf) in the oxidative phosphorylation pathway. In conclusion, BR likely enhances tomato tolerance to calcium deficiency stress and effectively reduces BER incidence through multiple pathways: regulating calcium absorption and distribution, activating the antioxidant system, modulating hormone signaling pathways, and enhancing energy metabolism. These findings provide a theoretical basis for the application of BR in agricultural production.

Blossom-end rot (BER) in tomatoes is a physiological disorder primarily caused by disrupted calcium absorption and transport. This study aims to investigate the physiological and molecular mechanisms by which exogenous brassinolide (BR) reduces the incidence of tomato BER under calcium-deficient conditions. The results showed that under calcium deficiency, foliar spraying of BR significantly reduced the BER incidence (from 26.67% to 6.67%) and effectively increased calcium ion content in the leaves, stems, roots, and other parts of the plant. At the physiological level, BR treatment significantly enhanced the activities of CAT, POD, and SOD in the leaves (by 105.70%, 117.12%, and 82.77%, respectively), while reducing the contents of H₂O₂ (by 36.90%) and MDA (by 16.38%). This indicates that BR alleviates membrane lipid peroxidation damage by enhancing the antioxidant defense system. Transcriptome analysis further revealed that BR treatment identified 4807, 2807, and 2554 differentially expressed genes (DEGs) in the leaves, stems, and roots, respectively, with the most significant response observed in the leaves. GO functional enrichment analysis showed that these genes are mainly involved in biological processes such as secondary metabolic processes, response to oxygen-containing compounds, and cell wall organization. KEGG pathway analysis further indicated significant enrichment in pathways such as phenylpropanoid biosynthesis, plant hormone signal transduction, and plant-pathogen interaction. Additionally, several key genes, such as the cytochrome C oxidase gene (Solyc03g013460.1), exhibited a gradient up-regulation pattern of "root > stem > leaf" in the oxidative phosphorylation pathway, while photosynthesis-related genes (e.g., PsbA, PsaA, and ND family genes) were also generally up-regulated. In summary, BR likely enhances tomato tolerance to calcium deficiency stress and effectively reduces the occurrence of BER through multiple pathways, including regulating calcium absorption and distribution, activating the antioxidant system, modulating hormone signaling pathways, and enhancing energy metabolism. This provides a theoretical basis for the application of BR in agricultural production.