Non-pathogenic and pathogenic leaf-colonising bacteria elicit qualitatively similar responses

Leaves are colonised by a complex mix of microbes, termed the leaf microbiota. Even though the leaf microbiota is increasingly recognised as an integral part of plant life and health, our understanding of its interactions with the plant host is still limited. Here, mature, axenically grown Arabidopsis thaliana plants were spray-inoculated with diverse leaf-colonising bacteria. Whole transcriptome sequencing revealed that four days after inoculation, leaf transcriptional changes to colonisation by non-pathogenic and pathogenic bacteria differed in strength but not in the type of response. Examination of aboveground Arabidopsis thaliana tissue treated either with different bacterial leaf colonisers (pathogenic and non-pathogenic) in comparison to mock-treated plants. Plants were grown in the ‘Litterbox’ system. Plants were 4-weeks-old at time of inoculation and sampled 96 h post inoculation.