Intercropping-induced shifts in root microbiota promote lead phytoremediation properties of Sonchus Asper

Abstract Intercropping or assistant-endophytes has been proven to promote phytoremediation capacities of hyperaccumulators and to enhance their tolerance to heavy metals (HM) stress. We initially showed that intercropping with maize improved the remediating properties of the hyperaccumulator Sonchus asper (L.) Hill grown in HM contaminated soils, accompanied by an excluder - to- hyperaccumulator switched mode of action towards lead. To characterize molecular events underlying this shift in lead extraction strategy, we conducted an RNA-Seq analysis on Sonchus roots grown in intercropping or monoculture. We show that intercropping only slightly affects the S. asper transcriptome, but dramatically impacts the expression of root associated microbial genomes. Further, intercropping triggers a severe reshaping of endophytic communities which accompanies a “root-to-shoot” transition of lead sequestration and improved phytoremediation capacities of S. asper. This study provides the clue that a unitive network of plant- microbial -plant interactions may participate to the phytoremediation abilities of hyperaccumulator plants and paves the path for innovative cultural practices aiming to cure polluted soils.