Impact of pest-induced Burkholderia inoculation on tea seedings: Integrated rhizosphere microbiome, transcriptome and metabolome profiling

In natural environments, plants often recruit beneficial organisms to mitigate various biotic and abiotic stresses, and our previous research identified that the root zone of tea plants infested by Ectropis grisescens Warren (Lepidoptera: Geometridae) accumulated Burkholderia microbes. This study explored the effects of single strain (S1) and mixed strain (S9) Burkholderia inoculations on rhizobacterial communities, and the transcriptomic and metabolic profiles of tea seedlings, aiming to clarify their roles in plant-microbe interactions. Inoculation with S9 enhanced Burkholderia colonization (4.7 % vs. S1:2.3 %) but reduced rhizobacterial diversity and network complexity, whereas S1 increased bacterial richness and community complexity; both treatments significantly altered bacterial community composition, with S1 upregulating 13 genera (e.g., Bacillus , Streptomyces ) and S9 downregulating 18 genera. Furthermore, FAPROTAX functional prediction analysis indicated that both the S1 and S9 treatments promoted soil nitrogen cycling functions, specifically nitrogen fixation and ureolysis. Transcriptomic profiling revealed that both treatments significantly altered gene expression patterns in tea seedling roots and leaves, with roots prioritizing amino acid synthesis and metabolism, while leaves emphasized the synthesis of defensive secondary metabolites. Metabolomic profiling identified 731 metabolites in tea leaves, with S1 exhibiting greater metabolic reprogramming than S9, highlighting 27 key compounds significantly altered by the inoculations. The results collectively underscore the potential of Burkholderia , both singly and in combination, to promote beneficial microbial associations and enhance the metabolic capabilities of tea seedlings, with implications for sustainable agricultural practices. • A Burkholderia strain and mixed community differently affect species composition, diversity, symbiotic networks in tea seedling root bacteria. • Introducing Burkholderia to tea rhizosphere altered gene expression, creating clear functional division between root and leaves. • Burkholderia triggered tea leaves to release esters and terpenes, boosting their defense.