Characteristics of microbial communities in the rhizosphere soil of potato (Solanum tuberosum L.) under different Cd contents in high-Cd geochemical background areas

Abstract

Microorganisms play an important role in soil contamination remediation, yet the characteristics of soil microbial communities under different soil Cd concentrations in areas with a high-Cd geological background remain poorly understood. Here, we determined Cd content in low Cd pollution (LP) and high Cd pollution (HP) soils from a high-Cd geological background area. Meanwhile, high-throughput sequencing of 16 S rRNA and ITS was used to characterize the bacterial and fungal communities composition in potato rhizosphere soil under the two Cd levels. This study showed that Cd content in potato tubers were low in both soil types, with a lower Cd exceedance rate observed in HP than in LP. In the both soils, Proteobacteria , Actinobacteria , and Acidobacteria were the predominant bacterial phyla; Thaumarchaeota and Ascomycota were the predominant archaeal and fungal phyla, respectively. Unlike archaea and fungi, bacterial alpha and beta diversity did not differ significantly between HP and LP. Redundancy analysis (RDA) showed that soil pH and organic matter were the most important environmental factors shaping bacterial, archaeal, and fungal communities. The microbial co-occurrence network was more complex in LP than in HP soil. Furthermore, functional prediction analysis indicated that microorganisms in HP soil had lower relative abundances of beneficial functional groups and higher relative abundances of potential harmful functional groups, which may negatively affect soil health. Interestingly, more bacterial keystone taxa in HP soil were significantly and positively correlated with soil total Cd content, suggesting that Cd-resistant functional microorganisms may be enriched in HP soils. These findings provide valuable insights into the screening and application of Cd-tolerant microorganisms for the remediation of Cd-contaminated soils.