Lysobacter: an emerging frontier in sustainable control of soilborne phytopathogenic microorganisms

Biological control of plant diseases has emerged in the last decades as a crucial strategy to control soilborne plant pathogenic (micro)organisms, while gradually reducing dependency on chemical pesticides. As global food security and sustainability concerns rise in agriculture, microbial BioControl Agents (mBCAs) residing in soils are increasingly recognized as supplementary and alternative strategies. While the genera Bacillus, Pseudomonas, and Trichoderma have been the focus of attention due to their diverse modes of action against soilborne plant pathogenic (micro)organisms, the gradual rise of the genus Lysobacter, a group of ubiquitous, nonmotile, Gram-negative bacteria, is a novel and intriguing development. This bacterial genus has been named based on its lytic activity towards (micro)organisms and comprises 73 species. The potential of Lysobacter spp. as versatile mBCAs is underscored by their ability to control plant pathogenic (micro)organisms through various modes of action. Indeed, Lysobacter spp. are known to secrete long- and intermediate-range weapons, such as secondary metabolites with antibiotic activity and lytic enzymes such as cellulases, chitinases, ß-1,3-glucanases, and proteases. These lytic enzymes and secondary metabolites act against Gram-positive and Gram-negative bacteria, fungi, oomycetes, nematodes, and protists in agricultural soils. In addition to their arsenal of antimicrobial compounds and lytic enzymes, Lysobacter spp. exhibit other mechanisms such as competition for space, predation, production of volatile compounds, and induction of plant resistance, some of which are considered short-range weapons. The increasing availability of Lysobacter spp. genomes have deepened our understanding of their molecular interactions with other (micro)organisms and the environment. Research has shown that Lysobacter spp. are highly abundant in disease-suppressive soils, where they play a significant role in inhibiting plant pathogens. Advances in omics technologies have highlighted the mechanisms by which Lysobacter spp. contribute to soil health and resilience, effectively targeting a wide array of plant pathogens, including fungi, bacteria, oomycetes, nematodes, and protists. The successful acclimatization of Lysobacter spp. in the soil depends on several factors, which aid in recruiting these bacteria to the rhizosphere. However, the mBCAs must often withstand harsh and hostile environmental conditions in natural settings. The recent advancement in formulations of mBCAs offers promising solutions to these challenges. Formulations with specific coformulants protect Lysobacter spp. from environmental stressors, enhancing their stability, viability, and efficacy in field applications. Together, better acclimatization strategies and optimized formulations enhance Lysobacter populations, linking their abundance in the soil to effective control of plant pathogens and sustainable crop protection. As research into the applications of Lysobacter mBCAs continues to evolve, with recent advancements in understanding their molecular interactions and formulation protocols, they hold the potential to revolutionize global agriculture toward sustainability.