Illumina MiSeq sequencing-bacterial 16S rRNA gene
For both AC (Amino acids + Carbohydrates) and FC (Fatty Acyls + Carbohydrates) treatments, aqueous solutions were prepared by combining equal concentrations of each selected compound to achieve a final total concentration of 10 mM. Specifically: AC solution (2 mM each): L-Alanine, L-Leucine, L-Valine, DL-Xylose, and Glycerol; FC solution (2 mM each): D-Tagatose, D-Galactose, Sucrose, Maltitol, and 3-O-Methyl-D-Glucose. Each well received 1.5 mL of treatment solution twice weekly for 8.5 weeks (17 total applications). Three treatments were applied: (1) AC solution (simulating OE-induced root exudates); (2) FC solution (simulating RNAi-induced root exudates); (3) Sterile water (control). To evaluate ARD suppression, we conducted a outdoor pot experiment at the Horticultural Experimental Station of Northwest A&F University, Yangling, China. The study comprised 3 treatments: 30-year-old orchard soil (CK, control), inactivated SynComs (Synthetic Microbial Communities) suspension (T1), and active SynComs suspension (T2).