Rhizosphere microbial communities of bacteria and fungi responding to cadmium stress in wheat

Cadmium (Cd) contamination in soil poses a threat to crop production and food safety. Rhizosphere microorganisms are crucial for crop growth and production; however, sufficient evidence regarding Cd-responsive bacteria and fungi within crop rhizosphere remains largely unknown. Here, we investigated the impacts of Cd on soil microbial communities in wheat rhizosphere by performing 16S and ITS sequencing under normal (CK) and Cd (10 μM) conditions. We found that low concentration of Cd significantly increased Cd concentration in wheat grains (nearly 0.2 mg.kg -1 ), but had no obvious growth inhibition. Interestingly, bacterial abundance and diversity were significantly decreased in soil rhizosphere when exposed to Cd, whereas little changes were observed in fungi. A total of 259 CK-specific and 45 Cd-specific operational taxonomic units (OTUs) in bacteria, as well as 3 CK-specific and 2 Cd-specific OTUs in fungi were identified. The function of identified bacteria were enriched in human diseases, organismal systems, metabolism, genetic information processing and environmental information processing. We also revealed a complicated bacterial co-occurrence network responding to Cd, including the core bacteria of Acidobacteria , Nitrospirae and Chloroflexi phylums. This study revealed Cd-responding bacteria and fungi communities in wheat rhizosphere, which may provide new insights into beneficial microorganisms for food safety.