Arsenic-triggered bacterial minorities correlate with arsenic accumulation in cabbage

Abstract

Arsenic (As) in vegetables imposes severe health risks. Selecting low As cultivars is a practical means to mitigate the risk; however, little is known about whether low-accumulating behaviour is related to the rhizosphere microbiota. From 18 cabbage cultivars, we identified high- and low-As transferring cultivars (HTC vs LTC) for a comparative study. Cabbages were grown in soils spiked with 0, 30, or 60 mg kg−1 of As. Plant physiological properties, As concentrations and speciation, and rhizosphere bacterial communities were analysed. The results showed that the LTC generally had more root activity, cell integrity, root antioxidants, and shoot chlorophyll than the HTC under As stress. Arsenic was the main factor driving the structure of the bacterial communities. The 60 mg As kg−1 treatment increased the proportion of bacterial minorities and altered the community co-occurrence networks. Gemmatimonadetes and Planctomycetes correlated positively and significantly with As concentrations in the HTC; however, these correlations were weaker in the LTC. Rhizosphere soils of the LTC, compared with those of the HTC, had more Patescibacteria, which might immobilise toxic ions in soils. The distinct behaviours of the HTC and LTC in harbouring bacterial communities under As stress might have a role in plant As uptake.