Organic matter and Bacillus niescheri amendments mitigate cadmium toxicity by regulating physiology and transcription of Diospyros lotus L., and soil bio-chemical properties

Abstract

Cadmium (Cd) is a hazardous heavy metal that threaten fruit safety and soil quality. The remediated effects of wheat straw and fruit pruning branch, with or without Bacillus niescheri, on the physiology and transcriptome of Diospyros lotus L., and soil bio-chemical properties in Cd condition were assessed in this study. Wheat straw and persimmon branch residue addition decreased the Cd availability in soil and Cd accumulation in tissues and alleviated oxidative damage caused by Cd as exhibited by the reduced O2•-, H2O2 and malondialdehyde contents in roots of D. lotus, especially following B. niescheri inoculation. Different expressed genes of ion uptake and translocation were mostly downregulated, whereas cell wall formation/modifications, amino acid metabolism, and phytohormone biosynthesis in roots were upregulated by organic matter plus B. niescheri. Furthermore, organic matter plus B. niescheri improved soil pH, electrical conductivity, cation exchange capacity, enzyme activity (urease, dehydrogenase, catalase), nutrients (nitrogen, phosphorus, potassium) and organic carbon contents. Soil Cd availability was negatively correlated with the relative abundance of Bacteroides, Cellvibrio, Bacillus, Sphingomonas, Vicinamibacteraceae, and Faecalibacterium. Therefore, the organic waste such as wheat straw and branch residues are eco-friendly methods of remediating Cd-contaminated soil and mitigating toxicity for D. lotus, especially following B. niescheri inoculation.