Hydrogen sulfide mediated alleviation of cadmium toxicity in <i>Phlox paniculata</i> 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 <i>Phlox paniculata</i> 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 <i>Phlox paniculate L.</i> 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.