Editorial: Role of Endophytes in Plant Health and Defense Against Pathogens

With the increasing social concern in avoiding, or at least reducing, the application of pesticides and chemical fertilizers, in favor of sustainable eco-friendly alternatives, the search for beneficial microorganisms and microbial-derived compounds has become one of the most popular Research Topics in the field of plant-microbe interactions (Cardoso Filho, 2019; Omomowo and Babalola, 2019). Bacterial and fungal endophytes ubiquitously inhabit plant tissues without causing any adverse effect. On the contrary, their presence is often of benefit for the host, as they improve tolerance to abiotic adversities, enhance growth, and, relevantly, can modulate plant immune response and suppress pathogen colonization (Dini-Andreote, 2020). Since endophytic microorganisms typically cover the same ecological niches occupied by fungal and bacterial phytopathogens, they have been widely proposed as biocontrol agents that could be used as an alternative to pesticides (Compant et al., 2013). Thanks to the multifaceted role they play, endophytic microbial resources are now considered crucial in the perspective of their potential use to achieve sustainable improvements in the agro-food system. As a consequence, there is now a scientific ferment trying to analyze every aspect of their interaction with plants and associated pathogens. With 16 Original Research Articles and one Review, this Research Topic provides an overview of the current state of the art on the large research effort currently dedicated to understanding the role of endophytes in plant health and defense against pathogens.