Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 7 April 2021 doi:10.20944/preprints202104.0186.v1 Review Bacterial endophytes: The hidden actor in plant immune re- sponses against biotic stress Nadira Oukala1, Kamel Aissat 1,3* and Victoria Pastor2,* 1 Laboratory of Ecological Microbiology, Department of Microbiology, Faculty of Nature and Life Sciences, University of Bejaia, 06000 Bejaia, Algeria;
[email protected] 2 Metabolic Integration and Cell Signaling Laboratory, Plant Physiology section, Departmento Ciencias Agrar- ias y del Medio Natural, Universitat Jaume I, 12071- Castelló de la Plana, Spain;
[email protected] 3 Department of Microbiology and Biochemistry, Faculty of Nature and Life Sciences, University of Batna 2, 05000, Batna, Algeria * Correspondence:
[email protected] Abstract: Bacterial endophytes interact closely with plant tissues and constitute an essential part of the plant microbiome. These interactions can promote plant growth and elicit specific defense re- sponses against abiotic stresses and pathogen attacks. In this paper, we review the role of endo- phytic bacteria in modulating defenses of the host rendering the entire plant more resistant to path- ogens and pests. The endophyte-induced resistance will probably introduce a new factor when con- sidering plant-pathogen interactions. The impact of the bacterial endosymbionts on the host leading to the priming state is also discussed since it confers a specific adaptation of the plant to the biotic threat. Keywords: Priming, Endophytic bacteria, ISR, Pathogens, Signalling 1. Introduction Plant endophytes are described as microorganisms that inhabit the internal parts of a plant and gain entrance into the root stem, leaf, flowers and seeds and they are not caus- ing apparent harm to the host plant [1].