Hydrogen sulfide mediated alleviation of cadmium toxicity in Phlox paniculata L. and establishment of a comprehensive evaluation model for corresponding strategy

Abstract

A laboratory experiment was performed to evaluate the potential role of H2S on cadmium (Cd) toxicity in Phlox paniculata L. Seeds pretreated with 0.3, 0.6, 0.9, and 1.2 mM NaHS as a donor of H2S for 24 h and subsequently exposed to 100, 200, and 300 μM CdCl2 for 26 days had significantly higher germination rate compared with Cd alone. Meanwhile, 2-year-old seedlings sprayed with 0.3, 0.6, and 0.9 μM NaHS were grown in soil with 0.3, 0.6, and 1.2 mg/kg CdCl2, respectively. We observed that H2S decreased Cd accumulation in leaves and elevated Cd concentration in roots. Cd toxicity in seedlings resulted in a substantial increase in Cd-induced overproduction of malondialdehyde (MDA), Cd accumulation, and electrolyte leakage. Meanwhile, addition of NaHS increased photosynthetic performance compared with Cd alone. Exogenous H2S significantly elevated biomass, improved antioxidant enzyme activities, and reduced ABA content compared with Cd alone. H2S also plays an important role in the ABA signaling pathway during stress. Notably, NaHS promoted Cd uptake by Phlox paniculate L. from soil. The prediction model of H2S for increasing plant resistance and reducing soil Cd pollution was established by factor analysis method based on comprehensive evaluation of plant stress physiology.