Fig. 9 | Scientific Reports

Fig. 9

From: Spermine treatment improves salinity tolerance in Plantago major by altering growth parameters, biochemical profiles and gene expression

Fig. 9

 (a) Heatmap showing Pearson correlation coefficients among morphological, physiological, and biochemical traits in Plantago major under various treatments. Positive correlations are shown in blue, negative correlations in red, with intensity indicating strength (r-values). Strong positive associations were observed among growth traits, while stress markers such as MDA and proline negatively correlated with photosynthetic and biomass parameters, highlighting the antagonistic interplay between growth and stress responses. (b) Heatmap of correlation analysis between gene expression levels (PAL, COMT, DAHPS, HMGR, Epoxidase) and corresponding metabolites (e.g., phenylalanine, caffeic acid, ferulic acid, rosmarinic acid, shikimic acid, ABA, spermine) in Plantago major. The analysis reveals strong gene–metabolite relationships, supporting transcriptional regulation of stress-induced secondary metabolic pathways. Color scale represents Pearson correlation coefficients (r), with positive and negative values indicating direct or inverse associations.

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