Faba bean (Vicia faba L.) seeds were treated with H2O [nonprimed (NP)] or 2% CaCl2 [primed (P)] before germination for 6 h. After seven days, seedlings were exposed to 0 or 50 µM CdCl2 concentrations for three weeks. Under Cd treatment, P plants showed an improvement of gas-exchange characteristics, chlorophyll (Chl) and carotenoids contents as compared to NP plants subjected to Cd stress. Additionally, the values of Chl fluorescence were relatively similar to those of control, implying that no photodamage occurred. Moreover, under 50 µM Cd, the P plants exhibited lesser accumulation of hydrogen peroxide and superoxide radicals in leaves as compared to NP plants. Likewise, results showed that CaCl2seed pretreatment alleviated adverse effects of Cd on electrolyte leakage. In conclusion, CaCl2 improved photosynthesis attributes of faba bean plants subjected to Cd stress by mitigating the adverse effects of Cd toxicity through a reduced generation of reactive oxygen species.Additional key words: nonphotochemical quenching; photosynthetic apparatus; seed priming; water-use efficiency. electron transport rate; F0 -minimal chlorophyll fluorescence; FM -fresh mass; Fm -maximal chlorophyll fluorescence; Fm' -maximal fluorescence yield of the light-adapted state; Fs -steady-state fluorescence yield; Fv -variable chlorophyll fluorescence; Fv/Fm -maximum photochemical quantum efficiency of PSII; gs − stomatal conductance; NPQ -nonphotochemical quenching; PN -net CO2 assimilation rate; ROS -reactive oxygen species; SE -standard error; WUE -intrinsic water-use efficiency (PN/gs); ФPSII -actual PSII efficiency. Acknowledgements: The authors are grateful for the financial support provided by the Tunisian Ministry of Higher Education and Scientific Research.

Alleviation of cadmium-induced root genotoxicity and cytotoxicity by calcium chloride (CaCl 2 ) in faba bean (Vicia faba L. var. minor) seedlings were studied. Faba bean seeds were treated with H 2 O or 2% CaCl 2 for 6 h before germination. Seeds were then exposed to 0 and 50 lM CdCl 2 concentrations for 7 days. Genotoxic damaging effects of Cd was examined through the determination of the mitotic index (MI), chromosomal aberrations (CA) and micronucleus (MN) in the meristem cells of faba bean roots. Similarly, effects of Cd stress on metal accumulation, total membrane lipid contents, total fatty acid composition (TFA), lipid peroxidation as indicated by malondialdehyde production, soluble protein and nonprotein thiols (NP-SH) contents, hydrogen peroxide production and the activities of superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPX) were evaluated after 7 days of Cd stress in the seedling roots. Cd stress resulted in the reduction of MI, in addition to MN formation and CA induction in the roots of non-primed seeds (treated with H 2 O). Moreover, Cd induced lipid peroxidation, H 2 O 2 overproduction and loss of membrane lipid amount and soluble protein content, and changes in the TFA composition in roots of faba bean seedlings. SOD activity declined, but CAT and GPX activities increased. However, seed pre-treatment with CaCl 2 attenuated the genotoxic and cytotoxic effects of Cd on Vicia faba roots. The results showed that CaCl 2 induced reduction of Cd accumulation, improved cell membrane stability and increased the antioxidant defence systems, thus reducing and alleviating Cd genotoxicity and oxidative damage.

No abstract