International Journal of Molecular Evolution and Biodiversity, 2025, Vol.15, No.2, 111-123 http://ecoevopublisher.com/index.php/ijmeb 116 reprogrammed, and the transcription of multiple heat shock protein (HSP) genes can even soar 50 times (Kourani et al., 2022). In addition, the epigenetic level is also involved in heat response regulation: high temperature treatment can cause demethylation of certain DNA segments, thereby activating the expression of heat-resistant genes (Figure 3). Figure 3 Regulatory and signaling events involved in plant heat stress response (Adopted from Kourani et al., 2022) Under low temperature conditions, signal transduction depends on the rapid mediation of calcium ions. Studies have found that the expression of CaM/CML family genes increased by 15 times in just 2 hours of 4°C stress treatment (He et al., 2020). CNGC-type ion channels assume the responsibility of "environmental sensors", sensing temperature changes and triggering fluctuations in intracellular calcium signals (Liu et al., 2021), initiating subsequent defense responses. 6.3 Molecular regulatory characteristics of salt stress Faced with high-salt environments, rapeseed responds to cytotoxicity by building an ion homeostasis regulatory system. Transcriptome data showed that within 1 hour of salt treatment, the expression of more than 800 genes had changed significantly (Chen et al., 2010). BnSIP1-1 can upregulate Na⁺ efflux channel-related genes, thereby reducing the sodium ion content in the roots by about 40% (Luo et al., 2017), effectively alleviating ion stress. At the same time, NDPK family members assist cells in maintaining the selective absorption of K⁺, balancing cell potential and osmotic pressure while ensuring signal transduction (Wang et al., 2024). In addition, the two-component regulatory system (TCS) exhibits a significant effect under salt stress, regulating the synthesis rate of osmotic protective substances. Rapeseed lines transformed with the TCS gene have a salt tolerance that is three times that of the wild type (Liu et al., 2023). This network, composed of signal perception, gene expression regulation and metabolic regulation, enables plants to respond dynamically to external changes, thereby maintaining survival and development in adversity. 7 Molecular RRegulatory Mechanisms of Biological Stress Response 7.1 Molecular basis of pathogen defense When fungal pathogens such as Sclerotinia sclerotiorum invade, the expression of CNGC ion channel genes in Brassica napus surges 8 times within 6 hours, triggering a calcium ion signaling cascade (Liu et al., 2021). GRF transcription factors act like precise molecular switches, coordinating the expression of disease-resistant genes by activating the two defense pathways of JA and SA (Sun et al., 2022). Mass spectrometry analysis revealed that nsLTPs protein content increased 5-7 times 72 hours after pathogen infection. These lipid-binding proteins may play a defensive role by destroying the cell membrane of pathogens (Xue et al., 2022).
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