International Journal of Molecular Evolution and Biodiversity, 2025, Vol.15, No.2, 111-123 http://ecoevopublisher.com/index.php/ijmeb 117 7.2 Induction mechanism of systemic resistance After 15 minutes of salicylic acid treatment, phospholipase C activity reached a peak, 12 times higher than the control group (Profotová et al., 2006). This rapid response suggests the presence of post-translational modifications such as protein phosphorylation, which is like a "start button" for the immune system. The ISR response induced by methyl jasmonate shows different kinetic characteristics: the signal transmission is slower but lasts longer, providing continuous protection for the plant. 7.3 Cross-regulation of stress signaling pathways UGTs enzymes are induced to express under various stresses, and their activity changes show an interesting pattern: they increase 3 times under salt stress and 5 times after pathogen infection (Rehman et al., 2018). nsLTPs show a wider spectrum of response characteristics, and are significantly accumulated under drought, low temperature and pathogen attack (Xue et al., 2022). Co-expression analysis of CNGC and GRF gene families revealed a core regulatory module: these genes showed similar expression trends under temperature stress and pathogen infection (correlation coefficient r>0.7), indicating that plants may respond to different stresses through conservative molecular mechanisms. 8 Study on Gene Expression Regulation of Brassica napus Under Drought Stress 8.1 Physiological effects of drought stress Water loss triggers a series of chain reactions in Brassica napus. The 35% decrease in plant fresh weight and the 42% decrease in dry weight reveal the significant inhibition of drought on biomass accumulation (Fang et al., 2022). The photosynthetic apparatus was significantly damaged, and the decrease in stomatal conductance led to a decrease in CO₂ assimilation rate of more than 40%. Interestingly, the seed metabolic profile was reprogrammed: while lipid synthesis decreased by 28%, protein content increased by 15% against the trend (Bianchetti et al., 2024). This metabolic conversion may be a survival strategy (Figure 4). The expression of genes related to active oxygen metabolism was upregulated by 3-5 times, suggesting the activation of the oxidative stress defense system (Liang et al., 2019). Figure 4 Seed development of Brassica napus (cv. ‘Express’) under various stress conditions (Adopted from Bianchetti et al., 2024) Image caption: A. Evolution of the seed water content (dotted line) and dry weight (DW, solid line) during seed development. Immature seeds were harvested at different timepoints (T) as depicted on pictures (bar 1 mm for all). Thermal times are given in growing degree-days (GDD). Data are expressed as the mean ± SE from three biological replicates of five seeds for each treatment. B. Mean values (solid line) with standard deviations (dashed lines) of soil water potentials (mbar) in eight (C and WS) or four (Pb and Pb + WS) replicated tanks over a 20-day window that frames the application of the drought stress. C. Relative expression level of RD20 (qRT-PCR) in mature leaves of B. napus plants grown under the different conditions (three biological rep. each). D. Number of plants with clubroot symptoms evaluated at the onset of WS application (4 rep. × 2 plants) or at the end of the crop cycle (4 rep. × 30 plants). C, control; WS, water shortage; Pb, P. brassicae inoculation; Pb + WS, P. brassicae inoculation and water shortage; rep., biological replicate (Adopted from Bianchetti et al., 2024)
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