Effects of inoculation with beneficial Serratia proteamaculans S4 and Verticillium longisporum on structure and allocation of plant-derived C in root and rhizosphere communities of oilseed rape
K. GKARMIRI (1), S. Mahmood (2), B. Andersson (2), S. Alström (2), N. Högberg (2), R. Finlay (2), K. Gkarmiri (1) (1) Swedish University f Agricultural Sciences, Sweden; (2) Swedish University of Agricultural Sciences, Sweden

The rhizosphere is an active niche where plant-derived carbon supports microbial growth. Serratia spp. have demonstrated plant growth promoting and antagonistic effects, and should compete more successfully than indigenous communities for plant-derived C and alter C allocation patterns. A greenhouse study was performed to identify microbial communities actively assimilating plant-derived C in root and rhizosphere of oilseed rape plants following inoculation with Serratia bacteria and the fungal phytopathogen Verticillium longisporum. Continuous labelling for 6 hours was initiated 4 weeks after the seeds were sown. No morphological differences or difference in shoot or root dry weight was observed between treatments. However total 13C enrichment in rhizospheric microorganisms was different between the treatments suggesting a treatment effect on carbon allocation below-ground, either in the level of microorganisms or due to increased root exudation because of stress. Preliminary bioinformatics analyses indicate that there is significant separation of RNA-active from DNA-abundant communities and clear separation between rhizospheric and root communities. In addition, the presence of different treatments seems to affect the abundance of indigenous microbial communities actively assimilating plant C. Communities such as Proteobacteria appear less abundant in DNA compared to RNA, indicating their key role in the active assimilation of plant-derived C.   

Abstract Number: P4-92
Session Type: Poster