In this work, we isolated four Cd-tolerant endophytic bacteria from Typha latifolia roots that grow at a Cd-contaminated site. Bacterial isolates GRC065, GRC066, GRC093, and GRC140 were identified as Pseudomonas rhodesiae. These bacterial isolates tolerate cadmium and have abilities for phosphate solubilization, siderophore production, indole acetic acid (IAA) synthesis, and ACC deaminase activity, suggesting that they are plant growth-promoting rhizobacteria. Bacterial inoculation in Arabidopsis thaliana seedlings showed that P. rhodesiae strains increase total fresh weight and number of lateral roots concerning non-inoculated plants. These results indicated that P. rhodesiae strains promote A. thaliana seedlings growth by modifying the root system. On the other hand, in A. thaliana seedlings exposed to 2.5 mg/l of Cd, P. rhodesiae strains increased the number and density of lateral roots concerning non-inoculated plants, indicating that they modify the root architecture of A. thaliana seedlings exposed to cadmium. The results showed that P. rhodesiae strains promote the development of lateral roots in A. thaliana seedlings cultivated in both conditions, with and without cadmium. These results suggest that P. rhodesiae strains could exert a similar role inside the roots of T. latifolia that grow in the Cd-contaminated environment.
Keywords: Cadmium tolerance; Endophytes; Plant growth-promoting rhizobacteria; Pseudomonas rhodesiae; Typha latifolia.