Application of exogenous jasmonic acid enhances the resistance of pak choi (Brassica chinensis L.) to high levels of selenium-toxicity in the soil

Enhancing selenium (Se) accumulation in crops is an important way to overcome human Se deficiency. However, increasing the Se content in the soil can produce toxic effects in crops. This study aimed to clarify the role of exogenous foliar jasmonic acid (JA) on alleviating Se toxicity of pak choi exposed to high levels of Se-toxicity in the soil.

Pak choi were exposed to high levels of soil Se stress and evaluate the physiological response, variation of Se accumulation and metabolites in the rhizosphere of plants treated with JA compared to those untreated under soil Se stress.

Se stress severely inhibited pak choi growth and biomass accumulation by reducing their photosynthetic capacity of photosystem II and inducing a heavy lipid peroxidation. When plants were sprayed with JA, 23.7% lower levels of lipid peroxidation was found, but higher levels of Fv/Fm (1.6%), Fvꞌ/Fmꞌ (11.8%), qP (40.0%), ETR (56.4%), catalase activity (82.8%), shoot biomass (38.1%) and Se content in the shoots (17.8%). Fifty-three metabolic compounds were altered in response to JA application compared to the Se group. Of those, JA application induced increased secondary metabolites of the rhizosphere, including organoheterocyclic compounds, lipids and lipid-like molecules, organic acids and derivatives, and benzenoids, which may be crucial for defense against Se stress and Se accumulation.

Foliar spraying with JA is an effective measure to alleviate the adverse effects of Se stress and enhance Se accumulation for optimizing crop Se biofortification in high Se soil.