Identification of beneficial microbes on the phyllosphere of Arabidopsis thaliana that inhibit the spread of Alternaria brassiciola

E Singh1, F Sharifah1, C Pieterse2, P Schenk1 and L Carvalhais1

  1. The University of Queensland, St Lucia, 4072, Queensland, Australia
  2. Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands

The phyllosphere hosts several complex microbial communities which have the ability to tolerate harsh environmental conditions. Current literature illustrates that there could be several beneficial microbes living on the foliar surface of leaves which may provide beneficial roles for the plants health and growth. We hypotheses that beneficial phyllosphere microbes may provide resistance against several foliar pathogens. However, there has only been minimal research conducted within this area, as opposed to beneficial microbes interacting in the rhizosphere. Our first results on strawberry phyllosphere microbiomes demonstrates that we can isolate leaf bacteria that successfully inhibit fungal pathogens. In this study, we have investigated the effect of the fungal pathogen Alternaria brassicicola Isolate 7 on the leaf microbiota of Arabidopsis thaliana. Amplicons of 16S rRNA gene sequencing were conducted for bacterial and fungal identification. Along with culture inhibition assays to screen for survivors and competitors of microbial communities, additionally a collection of leaf leachates and exudates from the phyllosphere were collected to create a substrate utilisation profile and colonisation pattern of the phyllosphere microbiota. Through these methods we found that there were naturally existing microbiota on the phyllosphere. Further analyses indicated that phyllosphere microbes also inhibit the spread of foliar pathogens and this can be significantly enhanced by the production of leachates to attract beneficial microbes. Future studies will integrate this study’s findings into creating new biocontrol agents, by isolating already resistant bacteria and applying them as a foliar spray to enhance plants resistance against pathogens.