Improvement of salt tolerance in Vicia faba (L.) seedlings: a comprehensive investigation of the effects of exogenous calcium chloride

This study investigated the effects of the different concentrations of CaCl2 (10 and 15 mol m−3) on the growth, physiology, and cytological characteristics of salt-stressed Vicia faba (L.) seedlings grown under greenhouse conditions. Salinity stress (150 mol m−3 NaCl) had detrimental effects on all measured growth parameters, increased the micronucleus count number (MCN) by 26.6 micronuclei/1000 cells, decreased the mitotic index (MI) by 66.6%, and caused various chromosomal aberrations, nuclear alterations, and chromatin bridges in salt-stressed seedlings compared to the untreated plant. Nevertheless, the seed priming with CaCl2 (10 and 15 mol m−3) significantly alleviated the toxic effects induced by salinity stress, improved growth parameters, total chlorophyll (TChl), proline, and total soluble sugar (TSS) contents in salt-stressed faba bean seedling compared with seedlings germinated from non-primed seeds. The antioxidative system of salt-stressed faba bean was highly stimulated by increasing the activity of catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) enzymes as well as phenolics and flavonoids were increased in all salt-stressed seedlings germinated from seeds primed with CaCl2 (10 and 15 mol m−3) indicating an improved tolerance of faba bean plant to salinity stress. Notably, the pretreatment with CaCl2 (10 mol m−3) reduced the micronuclei number per 1000 cells by 91.3% and decreased the abnormality index by 58.9% more effectively than CaCl2 (15 mol m−3). SDS-PAGE profiling revealed the presence of 16 proteins with different molecular weights, including two peptides, induced by CaCl2 (10 mol m−3) in response to salinity stress. This study showed that 10 mol m−3 CaCl2 significantly improved salt tolerance in treated faba bean plants mitigating the antagonistic effects of salt stress on several physiological and cytological parameters.