Abstract: Tea plants are aluminum-tolerant plants. Low concentration of aluminum promotes the growth of tea plants, but its regulation mechanism remains unclear. In this experiment, 38 strains of culturable endophytic bacteria were isolated and identified from the roots of tea plants treated with aluminum, including 27 strains of Firmicutes and 11 strains of Actinomycetes. Plant growth promoting abilities of the isolated endophytic bacteria were explored from ACC deaminase, phosphate solubilization, siderophore and IAA production. It was found that the comprehensive plant growth promoting abilities of Firmicutes FBA, FPC and Actinomycetes AMM, ACP032155 were better. The relative activities of the 38 strains at different aluminum ion concentrations were further investigated. The results show that the 38 strains of endophytic bacteria could survive under 1 mmol·L^-1 Al^{3 +} concentration, among which Actinomycetes AME2 could still survive under 8 mmol·L^-1Al³⁺, which showed the strongest aluminum tolerance. The results show that aluminum treatment could promote the growth of aluminum-tolerant bacteria in tea plants, thus indirectly promoting the growth of tea plants. This study laid a foundation for the cultivation and breeding of endophytic bacteria of tea plants with significant aluminum tolerance and growth promotion ability.

Key words: root, endophytic bacteria, aluminum tolerance, promoting growth abilities