Hung, S.-H. W.; Yeh, P.-H.; Huang, T.-C.; Huang, S.-Y.; Wu, I.-C.; Liu, C.-H.; Lin, Y.-H.; Chien, P.-R.; Huang, F.-C.; Ho, Y.-N.; Kuo, C.-H.; Hwang, H.-H.; Chiang, E.-P. I.; Huang, C.-C.

In response to climate change, the nature of endophytes and their applications in sustainable agriculture has attracted the attention of academia and agro-industries. We focused on the endophytic halophiles of the endangered Taiwanese salt marsh plant, Bolboschoenus planiculmis, and evaluated the functions of the isolates through in planta salinity stress alleviation assay using Arabidopsis. An endophytic strain Priestia megaterium BP01R2 that could promote plant growth and salinity tolerance was further characterised through multi-omics approaches. The transcriptomics results suggested that BP01R2 could function by tuning hormone signal transduction, energy-producing metabolism, multiple stress responses, etc. In addition, a cyclodipeptide, cyclo(L-Ala-Gly), identified by metabolomics analysis was later confirmed to contribute to salinity stress alleviation in stressed plants by exogenous supplementation. Here we provide a new perspective on host-microbe interactions in the wetland biome based on the multi-omics investigation and mixotrophic character of BP01R2. This study revealed a biostimulant-based plant-endophyte symbiosis with potential application in sustainable agriculture and facilitated our understanding of those enigmatic cross-kingdom relationships.