Exploring the phyllosphere bacterial community for improving tree crops protection

Plants are able to interact with plentiful bacteria resulting in a number of positive or negative outcomes for plant health. The ecological balance between pathogens and beneficial bacteria could be strategically disturbed and manipulated for improving host plant protection. As bacterial communities present in the phyllosphere of herbaceous plants have been largely studied, a number of biocontrol agents for controlling host diseases are already identified and used with promising results. A few studies on the use of phyllosphere biocontrol agents on woody crop tree plants have revealed encouraging results toward a future where plant disease control could be attained without the application of chemical compounds. In addition to the use of biocontrol agents, disease suppression can be achieved by the manipulation of microbial communities through plant management practices. In this review, an overview of the available knowledge on phyllosphere bacterial communities of woody tree crop species is provided, giving special emphasis to the structural differences of bacterial communities living on and within important tree crop species. Studies and challenges on the application and/or manipulation of these bacteria under in planta conditions are discussed, disclosing new sustainable ways for dealing with woody crop diseases.This work was partially funded by European Structural and Investment Funds in the FEDER component, through the Operational Competitiveness and Internationalization Programme (COMPETE 2020); and national funds, through the FCT – Portuguese Foundation for Science and Technology under the project POCI-01-0145-FEDER-031133. J.D. Mina thanks FCT, POPH-QREN and FSE for PhD grant SFRH/BD/105341/2014