Production of Agrocinopine A by Agrocinopine Synthase in Transgenic Tobacco and Its Effect on the Rhizosphere Microbial Community.

is a bacterial pathogen that causes crown gall disease on a wide range of eudicot plants by genetic transformation. Besides T-DNA integrated by natural transformation of plant vegetative tissues by pathogenic spp., previous reports have indicated that T-DNA sequences originating from an ancestral sp. are present in the genomes of all cultivated sweet potato () varieties analyzed. Expression of an -derived agrocinopine synthase (ACS) gene was detected in leaf and root tissues of sweet potato, suggesting that the plant can produce agrocinopine, a sugar-phosphodiester opine considered to be utilized by some strains of spp. in crown gall. To validate the product synthesized by ACS (IbACS), we introduced into tobacco under a constitutive promoter. High-voltage paper electrophoresis followed by alkaline silver nitrate staining detected the production of an agrocinopine-like substance in -expressing tobacco, and further mass spectrometry and nuclear magnetic resonance analyses of the product confirmed that IbACS can produce agrocinopine A from natural plant substrates. The partially purified compound was biologically active in an agrocinopine A bioassay. A 16S ribosomal RNA amplicon sequencing and meta-transcriptome analysis revealed that the rhizosphere microbial community of tobacco was affected by the expression of . A new species of (actinobacteria) was isolated as an enriched bacterium in the rhizosphere of -expressing tobacco. This sp. can catabolize agrocinopine A produced in tobacco, indicating that the production of agrocinopine A attracts rhizosphere bacteria that can utilize this sugar-phosphodiester. These results suggest a potential role of conserved among sweet potato cultivars in manipulating their microbial community.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.