P-246 - Indole alkaloids in plant-microbe interactions: Microbial detoxification and biochemical effects on plants

Shaping the soil microbiome by plant secondary metabolites covers an important domain in plant-microbe interactions. The supplementation of the two indole metabolites BOA and gramine to agricultural soil revealed metabolite-dependent shifts in the bacterial composition. Several tolerant bacteria strains from BOA-treated soil were found that is able to survive after the exposure to BOA-derived 2-acetoaminophenol (AAP), and it could nitrate AAP in subsequent reactions. Exposure to nitro-AAP derivatives resulted in the up-regulation of terpene synthase (TPS04) expression in A. thaliana and increased the production of geranyllinalool that is known to inhibit sphingolipid metabolism in herbivores and plants. One Arthrobacter sp. isolated from gramine-treated soil was able to degrade gramine via indole-3-carboxaldehyde (I3A) and indole-3-carboxylic acid (I3C). Transcriptomic and p</span>roteomic analysis revealed that peroxidases in Arthrobacter sp. are involved in early stage gramine degradation. I3A and I3C application resulted in increased fresh weight and induced root development of A. thaliana. Real-time qPCR showed up-regulation of several auxin-responsive genes in A. thaliana. Furthermore, the expression pattern of signal transduction and defense mechanism related genes in I3A and I3C treated Arabidopsis were similar with auxin treated A. thaliana. Taken together, our data highlights the importance of plant secondary indole metabolites during plant-microbe interactions.