Exogenous salicylic acid signal reveals an osmotic regulatory role in priming the seed germination of Leymus chinensis under salt-alkali stress

Priming agents play an important regulatory role in improving the plant seed vigor in response to abiotic stresses. However, lower germination rate of the seeds has been an obstacle factor limiting the propagation of Leymus chinensis, especially in the soils of salinization-alkalinization. In this study, the seeds of Leymus chinensis were soaked by salicylic acid priming to investigate whether exogenous salicylic acid participates in the osmotic regulation in the germinating seeds of Leymus chinensis under salt-alkali stress. Here, we report the priming effects of salicylic acid on promoting the germination rates of Leymus chinensis seeds. Data showed that exogenous salicylic acid priming increased the influx of O2 in the germinating seeds of Leymus chinensis under salt-alkali stress, thus increasing the respiration strength and triggering a series of physiological changes in the germinating seeds. Our measurements show that exogenous salicylic acid beneficially modulated the distribution of endogenous hormone signal molecules such as abscisic acid, gibberellin, indole-3-acetic acid and salicylic acid. Exogenous salicylic acid balanced the osmotic potentials and lowered the osmotic damage to the plasma membrane by mediating the accumulation profiles of ions such as Na+, K+, and Ca2+ as well as compatible metabolites such as proline and soluble sugar. Priming with exogenous salicylic acid increased the efflux of Na+ and inhibited the efflux of K+ and Ca2+, thus lowering the accumulation of Na+ and retaining more K+ and Ca2+ in the germinating seeds of Leymus chinensis under salt-alkali stress, thus improving the activities of the antioxidant enzymes, reducing lipid membrane peroxidation damage, and promoting the accumulation of signal factor H2O2 and the germination rates of Leymus chinensis seeds.

Automated summary

Priming with exogenous salicylic acid promoted germination rates of Leymus chinensis seeds by increasing O2 influx, modulating endogenous hormone distribution, balancing osmotic potentials, and reducing osmotic damage. This led to improved antioxidant enzyme activities and reduced lipid peroxidation damage, ultimately promoting seed germination.