Endophytic pyrroloquinoline quinone enhances banana growth and immunity against Fusarium wilt for plant-microbe mutualisms

Fusarium wilt has a substantial impact on global banana production, posing a threat to food security worldwide. However, breeding new Fusarium-resistant cultivars is difficult and time-consuming. Alternatively, endophytic biostimulants that could combat such pervasive plant diseases provide possible novel solutions. Our prior research demonstrated that a pyrroloquinoline quinone (PQQ)-producing endophytic bacterium, Burkholderia seminalis 869T2, can enhance the growth of various plant species and protect bananas from Fusarium wilt in the field. PQQ is a peptide-derived redox cofactor known to stimulate mitochondrial biogenesis and metabolism in animals, but its molecular roles, especially in plants, remain to be elucidated. In this study, multi-omics approaches were employed to explore the potential mechanisms through which PQQ influences banana plants. The result of in situ imaging mass spectrometry revealed that the endophytic metabolite PQQ does not function through direct antagonism against Fusarium. The follow-up transcriptomic profiling shows it could regulate plant respiration, TCA cycle, oxidative phosphorylation, NAD/NADP-dependent dehydrogenases, MAPK signalling, and various phytohormone signalling pathways. Furthermore, PQQ appeared to trigger plant systemic immunity, thereby enhancing plant health and resistance to biotic stress. Beyond that, the complete genome of 869T2 was determined for follow-up comparative genomics analyses, revealing its genetic contexts, potential evolutionary events of PQQ operons among the Burkholderia species, and the absence of human virulence-facilitating genes within those PQQ-producing agricultural isolates. In summary, this study facilitates our understanding of PQQ in plant-microbe mutualisms and provides scientific evidence for its future application in agriculture.