Drought legacy effects enhance tea plant drought tolerance by modulating the rhizosphere core microbiota

The drought legacy effects significantly influence the drought resistance of plants; however, research examining the drought legacy effects of drought on tea plants remains limited. This study employed a two-stage pot experiment to simulate drought residual effects and investigate their influence on tea plants. Results indicated that the root-to-shoot ratio in the drought-drought treatment (DRY-D) was 55.26% higher than in the wetted-drought treatment (WET-D), accompanied by significant increases in the levels of abscisic acid, indole-3-acetic acid, and trans-zeatin riboside. Furthermore, drought legacy effects prompted a restructuring of the rhizosphere microbial communities. Notably, significant differences were observed in the relative abundance of 54 operational taxonomic units (OTUs) between DRY-D and WET-D. The drought legacy also altered the rhizosphere bacterial network of tea seedlings, which exhibited characteristics of a 'small-world' network with modular architecture. However, variations in community cohesion were evident across treatments. Specifically, the bacterial community in WET-W predominantly displayed mutualistic interactions, whereas competitive interactions intensified in WET-D. In drought-wetted treatment (DRY-W), positive and negative bacterial interactions were balanced, while positive interactions predominated in DRY-D. Core bacterial taxa were identified within each treatment group, with 13, five, 14, and four core bacteria detected in wetted-wetted treatment (WET-W), WET-D, DRY-W, and DRY-D, respectively. The core bacterial community in DRY-D played a pivotal role in maintaining the integrity and stability of the microbial network. Overall, the drought legacy enhanced the drought resistance of tea plants by restructuring the rhizosphere core microbial community, thereby providing a foundation for improving tea plant drought tolerance through microbial inoculation strategies.