Exogenous Hydrogen Sulfide Ameliorates Seed Germination and Seedling Growth of Cauliflower Under Lead Stress and Its Antioxidant Role

Lead (Pb) is a widespread ecosystem pollutant and affects food security and public health. Hydrogen sulfide (H2S) plays prominent roles in mediating a variety of responses to stresses. The effects of sodium hydrosulfide (NaHS), a fast releaser of H2S, on cauliflower (Brassica oleracea L. var botrytis L. cv. Xiahua 60 d) seed germination and seedling growth under lead acetate stress were investigated in the present study. Pb (0.25 and 0.5 mM) stresses markedly inhibited seed germination and seedling growth, whereas the inhibition was effectively mitigated by NaHS application. Germination percentage, root length, shoot length, and fresh weight of single seedling significantly increased. In addition, NaHS elevated endogenous H2S contents and reduced malonyldialdehyde, superoxide anion (), and hydrogen peroxide (H2O2) production, thereby preventing oxidative damage from Pb or Pb and antioxidant enzyme inhibitor (diethyldithiocarbamate or 3-amino-1,2,4-triazole) dual stresses. The protective roles of NaHS were equivalent to the ROS scavengers, 4,5-dihydroxy-1,3-benzene disulfonic acid? and N,N'-Dimethylthiourea. Moreover, NaHS elevated non-protein thiols and total glutathione levels to chelate Pb or scavenge ROS directly. Our results demonstrated the strong protective and antioxidant roles of H2S.