The association between
hydrogen sulfide (H2S) and cell wall composition with regard to the mitigation of
cadmium (Cd) toxicity in Brassica napus L. was investigated. Cd caused growth retardation, leaf
chlorosis, and decreased endogenous H2S content in Brassica napus roots. Stimulating
l-cysteine desulfhydrase (LCD)-mediated H2S production with H2S releaser (
NaHS) markedly improved plant growth, reduced Cd content in stems and leaves, and rescued Cd-induced
chlorosis. Furthermore, increased Cd retention was observed in root cell walls, indicating that
NaHS reduced Cd movement from the roots to upper-plant parts. Exogenous
NaHS also significantly increased the content of
pectin and the activity of
pectin methylesterase in cell walls of roots, thereby increasing Cd retention in
pectin fractions. However, intensification of H2S barely affected
hemicellulose content under Cd stress. Intensified H2S signal, therefore, alleviates Cd toxicity in Brassica napus by increasing
pectin content and its demethylation, increasing Cd fixation in cell walls, and reducing root-to-shoot Cd translocation.