Editorial: Beneficial Microbiota Interacting With the Plant Immune System.

Abstract

The Green Revolution during the 50s and 60s was a milestone in the history of mankind. Based on the principles “higher yields, more food, less poverty and hunger,” it radically transformed agriculture and dramatically increased global food production (Khush, 2001). Despite the success, intensive agricultural practices that include the exhaustive use of synthetic fertilizers and agrochemicals and the overexploitation of natural resources, eventually came with serious environmental costs (Tang et al., 2021). Today, more and more farmers around the world realize that the soils used to cultivate monocultures for many years are rapidly degrading (Banwart, 2011). In addition, the withdrawal of agrochemicals from the market that are effective but unsafe for the environment and the consumer health created additional difficulties in the control of devastating pathogens and pests. With the advent of a rapidly growing human population, anticipated to reach about 10 billion people by the year 2050 (FAO, 2009), a new revolution in agriculture seems to be more timely than ever in order to sustain and further increase food production (Evans and Lawson, 2020). Plants are massively colonized by communities of microbes that are referred to as the plant microbiota. Plant-associated beneficial microbes have long been known to provide important ecosystem services and promote plant health by enhancing growth, suppressing pathogens and training plant immunity (Berendsen et al., 2012; Trivedi et al., 2020). Lorenz Hiltner, a pioneer of microbial ecology, was the first to recognize the important role of beneficial bacteria that colonize the rhizosphere (Hartmann et al., 2008). Since then, our understanding regarding the structure and the function of the plant microbiomes has been greatly improved (Tian et al., 2020). Towards a new Green Revolution that is protective to the environment and safe to humans, the enhanced interest in the plant microbiome clearly stems from its strong potential to provide eco-friendly solutions in plant disease protection and novel tools to promote sustainability in agroecosystems (Qiu et al., 2019). Understanding the complexity of plant-microbiome interactions is essential to transform fundamental knowledge to microbiome-informed innovations in modern agriculture. We host here in this Research Topic, “Beneficial Microbiota Interacting with the Plant Immune System,” 16 articles that enhance our knowledge on the supportive functions of beneficial microbes in plant disease resistance. In particular, the Topic contains research articles focusing on the protective functions of individual biological control agents (BCAs) against important diseases in agricultural and forest ecosystems, but also metagenomic studies that provide a more holistic view on the way microbiota interact with plant immunity. In addition, one method paper presents a pipeline to dissect selected plant responses to bacteria with different lifestyles and 5 review articles summarize our current knowledge on the mechanisms by which beneficial bacteria and fungi promote host defenses and plant health in below- and aboveground plant tissues. New experimental platforms and integrated approaches that combine (meta)-omics with functional analyses are needed in future research in order to obtain a comprehensive understanding of the mechanisms by which beneficial microbes interact with phytopathogens and plant immunity.