CaCl₂ priming promotes sorghum seed germination under salt stress by activating sugar metabolism

Salt stress notably inhibits the germination of sorghum seeds. CaCl2 priming effectively promotes seed germination under salt stress, but the underlying mechanisms remain unclear. This study explored the CaCl2 -primed regulation of sorghum seed germination under salt stress. Hydro-primed seeds (HPS) and CaCl2-primed seeds (CaPS) were cultured under salt stress (150 mM NaCl). The no-primed seeds were cultured in distilled water (no salt) (NPN) or 150 mM NaCl stress (NPS). Primed and unprimed seeds were evaluated for amylase activity, starch content, sugar metabolism, and mitochondrial repair. We found that salt stress significantly inhibited sorghum seed germination and reduced the germination rate. It also decreased amylase activity, starch decomposition, and sugar accumulation during germination, indicating inhibition of sugar metabolism. However, CaCl2 priming reversed the adverse effects of salt stress, increasing amylase activity, starch decomposition, and sugar content. It also up-regulated the expression of genes for phosphofructokinase and other enzymes involved in the glycolytic, tricarboxylic acid cycle (TCA), and pentose phosphate pathways. CaCl2 priming also resulted in the repair and maintenance of mitochondrial structural integrity, contributing to activation of the TCA cycle. In short, CaCl2 priming promotes sorghum seed germination by activating sugar metabolism under salt stress and provides a strategy for improving seed germination during agricultural production.