Agricultural Jiaosu Enhances the Stress Resistance of Pak Choi (Brassica rapa L. subsp. chinensis) by Recruiting Beneficial Rhizosphere Bacteria and Altering Metabolic Pathways

Agricultural Jiaosu (AJ) is a method of recycling agricultural wastes for improving soil properties, promoting plant growth, and enhancing plant stress resistance. However, the underlying mechanism by which AJ improves plant stress resistance needs to be determined. Therefore, in this study, two treatments of AJ spraying and water spraying were set up to determine the enzyme activities related to the stress resistance of pak choi after 30 days of growth, and the potential mechanism of AJ’s influence on the stress resistance of pak choi was revealed by transcriptome, metabolome, and rhizome microbiome analyses. Microbial community analysis revealed that the application of AJ does not alter microbial abundance in the rhizosphere; however, it can improve microbial diversity and enrich Actinobacteriota, Proteobacteria, and Firmicutes in the pak choi rhizosphere. Metabolomic analysis revealed that these phyla were significantly positively correlated, with highly upregulated metabolites. Our findings suggest that AJ recruits beneficial microorganisms (BMs) in the rhizosphere and stimulates the expression of genes and metabolites involved in phenylpropanoid and glucosinolate biosynthesis, as well as glutathione and alpha-linolenic acid metabolism pathways. The use of AJ could considerably minimise the use of pesticides and fertilisers and improve the quality of the ecological environment.