Saline Stress Impairs Lipid Storage Mobilization during Germination in Eruca sativa

Soil salinization become worse in the last decades, leading to reduced crop yields, especially in the Mediterranean basin. Eruca sativa is a common species cultivated in this area with remarkable economic importance. This study aimed at investigating the effect of salinity on this plant, focusing on (i) seedling development in terms of variations in germination and growth parameters and (ii) anatomical and ultra-structural changes in the morphology of cotyledons. For this reason, seeds were treated with different salinity levels ranging from 137 to 548 mM NaCl. Seed germination was delayed by all the concentrations tested, but only above 137 mM seedling growth was impaired. Results showed a high occurrence of lipid bodies within the mesophyll cells of cotyledons of seedlings exposed to salt concentrations above 137 mM, suggesting an impairment in lipid mobilization caused by salinity during plant development. The cotyledons of treated seedlings showed reduced intercellular spaces and ultrastructural changes in chloroplasts and peroxisomes. Moreover, salt-induced autophagic processes were present in samples grown at the highest NaCl levels. Interestingly, at 137 mM NaCl, seedlings showed the highest values of mesophyll thickness and fresh weight, implying a possible mechanism of salt adaptation during germination.

Automated summary

Soil salinization has worsened in recent decades, resulting in decreased crop yields, particularly in the Mediterranean basin. Eruca sativa is an economically important species cultivated in this region. This study aimed to investigate the effects of salinity on the germination and growth of seedlings, as well as the anatomical and ultrastructural changes in cotyledon morphology. Seeds were treated with varying levels of NaCl, ranging from 137 to 548 mM. Seed germination was delayed at all tested concentrations, but impaired seedling growth occurred only above 137 mM. Results showed a high presence of lipid bodies in the cotyledon mesophyll cells of seedlings exposed to salt concentrations above 137 mM, indicating a disruption in lipid mobilization during plant development caused by salinity. Treated seedlings exhibited reduced intercellular spaces, ultrastructural changes in chloroplasts and peroxisomes, and salt-induced autophagic processes at the highest NaCl levels. Interestingly, seedlings at 137 mM NaCl displayed the highest mesophyll thickness and fresh weight, suggesting a potential mechanism of salt adaptation during germination.