Cross-Kingdom Conversations: Deciphering Molecular Interactions in Microorganisms and Plants

Dear Colleagues,

Plant growth-promoting microorganisms (PGPMs) engage in complex molecular interactions with host plants, significantly influencing nutrient acquisition, stress resilience, and immune responses. These cross-kingdom communications are mediated by diverse molecular signals such as phytohormones (e.g., IAA, ABA, GA₃, melatonin), small RNAs, quorum sensing molecules (e.g., flagellin, LPS, AHLs), and volatile organic compounds (VOCs). For example, Pseudomonas fluorescens alters root architecture through IAA production and induces systemic resistance via flagellin-derived peptides, while arbuscular mycorrhizal fungi (AMF) utilize Myc factors to initiate calcium-mediated signaling in plants. PGPMs also facilitate nitrogen and phosphorus transformations and produce phytohormones that directly regulate plant growth. Additionally, PGPM produce phytohormones such as gibberellic acid (GA₃), and cytokinin, melatonin which play direct roles in regulating plant growth and development and modulated the redox signaling and abiotic stress tolerance.

Despite these advances, current research is often constrained by reductionist approaches focused on single-strain models, limiting our understanding of the dynamic and multifactorial nature of plant-microbiome interactions. Key gaps remain in deciphering the specificity of signaling molecules, mechanisms of receptor recognition, transcriptional reprogramming, and how plants process multiple microbial cues in complex environments. Additionally, the molecular determinants of microbial compatibility, colonization efficiency, and community assembly are not yet fully understood.

This Special Issue seeks to address these challenges by highlighting interdisciplinary research that uncovers the molecular foundations of cross-kingdom communication. We welcome submissions employing integrative approaches such as multi-omics, metabolomics, genome editing, synthetic microbial communities (SynComs), and systems biology. Studies that reveal novel signaling networks, molecular regulators, or functional metabolites involved in plant–microbe interactions are particularly encouraged.

By deepening our mechanistic understanding of how plants and microbes perceive and respond to molecular cues, this Issue aims to foster innovative microbial applications in sustainable agriculture and environmental resilience.

Dr. Eun-Hae Kwon
Guest Editor

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