Volatiles of two growth-inhibiting rhizobacteria commonly enroll AtWRKY18 function

Volatiles of certain rhizobacteria can cause growth inhibitory effects on plants/ Arabidopsis thaliana. How these effects are initiated and which mechanisms are enrolled is not yet understood. Obviously the plant can survive/live with the bacteria in the soil, which suggest the existance of a regulatory mechanism/network that provide the possibility for coexistance with the bacteria. To shed light on this regulatory mechanism/network we performed a microarray anlaysis of Arabidopsis thaliana co-cultivated with two different rhizobacteria strains. In this study we used the ATH1 GeneChip microarray to investigate the transcriptional response of 4 to 5 days old Arabidopsis thaliana seedlings at 6 h, 12 h and 24 h exposure to volatiles of the rhizobacteria Serratia plymuthica HRO-C48 or Stenotrophomonas maltophilia R3089. Seedlings from Arabidopsis thaliana were harvested at different time points at exposure to volatiles of two different strains of bacteria. Samples were taken at the start of the experiment (T0) and after 6, 12 and 24 hours (T6, T12, T24 respectively). Two biological replicates from pooled seedlings (from 5 plates, from the respective time points) were used for RNA extraction and hybridization on Affymetrix microarrays (ATH1 GeneChip; GEO accsession GPL198).