Harnessing eCISs for precision phytomicrobiome engineering and biocontrol.

Plant microbiome disruption often increases vulnerability to crop diseases, endangering worldwide food production, while chemical pesticides become increasingly less viable and continue to damage ecosystems. To safeguard plant microbiome health, several biological control strategies offer alternatives, yet many operate through broader or weakly defined target mechanisms. In recent years, bacterial contractile injection systems (BCISs) have emerged as a promising class of naturally evolved nanomachines that translocate molecular payloads directly into target cells. Subsets of these systems, extracellular contractile injection systems (eCISs), are distinguished by their specific narrow host range and receptor-dependent specificity. Recent studies have demonstrated that eCISs provide a transformative approach for targeted microbial manipulation, enabling the delivery of specialized molecules into particular microbes with higher precision. However, despite their potential, the integration of these engineered injection systems with microbial modulation for phytomicrobiome remains largely underexplored. Here, we explore the capabilities of eCISs as an advanced approach for the biocontrol, leveraging their tailored mechanisms for targeted payload delivery in plant-associated microbial communities with enhanced host specificity. This study aims to address the potential of engineered injection systems in facilitating sustainable phytomicrobiome engineering strategies that enhance biocontrol, aiming to reduce environmental harm while improving agricultural productivity.