Hydrogen sulfide mitigates cadmium induced toxicity in Brassica rapa by modulating physiochemical attributes, osmolyte metabolism and antioxidative machinery

Abstract

Hydrogen sulfide (H2S) is helpful for maintaining plant growth under abiotic stresses. The current study elucidated the physiological and biochemical strategies by which sodium hydrosulfide (NaHS), a donor of H2S, alleviated cadmium (Cd) toxicity in Brassica rapa. B. rapa plants growing under 50 mgkg−1 Cd stress showed reduced leaf relative water contents (LRWC), photosynthetic pigments, total soluble proteins, minerals uptake, antioxidants and growth. Furthermore, enhanced accumulation of Cd contents caused augmentation in levels of electrolyte leakage (EL) and methylglyoxal (MG). Nevertheless, improved physiochemical parameters in B. rapa seedlings obtained from seeds primed with 1.5 mM NaHS resulted better phenotype, growth and biomass production in Cd stressed plants. Protective stimulus of H2S regulated minerals and Cd homeostasis besides increased activity of antioxidants which decreased level of reactive oxygen species (ROS), EL, malondialdehyde (MDA) and MG in Cd regimes. Furthermore, H2S treated seedlings exhibited reduction in Cd content and revealed an active participation in the indole acetic acid (IAA) mediated pathway during stress. The findings of current study propose that H2S improved stress tolerance and mitigated Cd stress in B. rapa by modulating growth biomarkers and antioxidative system.