The multi metal-resistant bacterium Cupriavidus metallidurans CH34 affects growth and metal mobilization in Arabidopsis thaliana plants exposed to copper

Abstract

Copper (Cu) is important for plant growth, but high concentrations can lead to detrimental effects such as primary root length inhibition, vegetative tissue chlorosis, and even plant death. The interaction between plant-soil microbiota and roots can potentially affect metal mobility and availability, and, therefore, overall plant metal concentration. Cupriavidus metallidurans CH34 is a multi metal-resistant bacterial model that alters metal mobility and bioavailability through ion pumping, metal complexation, and reduction processes. The interactions between strain CH34 and plants may affect the growth, metal uptake, and translocation of Arabidopsis thaliana plants that are exposed to or not exposed to Cu. In this study, we looked also at the specific gene expression changes in C. metallidurans when co-cultured with Cu-exposed A. thaliana. We found that A. thaliana’s rosette area, primary and secondary root growth, and dry weight were affected by strain CH34, and that beneficial or detrimental effects depended on Cu concentration. An increase in some plant growth parameters was observed at copper concentrations lower than 50 µM and significant detrimental effects were found at concentrations higher than 50 µM Cu. We also observed up to a 90% increase and 60% decrease in metal accumulation and mobilization in inoculated A. thaliana. In turn, copper-stressed A. thaliana altered C. metallidurans colonization, and cop genes that encoded copper resistance in strain CH34 were induced by the combination of A. thaliana and Cu. These results reveal the complexity of the plant-bacteria-metal triad and will contribute to our understanding of their applications in plant growth promotion, protection, and phytoremediation strategies.

Bioremediation potential of consortium Pseudomonas Stutzeri LBR and Cupriavidus Metallidurans LBJ in soil polluted by lead

“…The low Pb reduction rate in the sterile and non-sterile soil bioaugmented only with the strain C. metallidurans LBJ (41.86% and 46.47% respectively) compared to the Pb rate reduction in the sterile and non-sterile soil bioaugmented with P. stutzeri LBR only is explained by the higher affinity of C. metallidurans LBJ to Cadmium compared to Pb and thereby an average capacity of biosorption to some other metals despite being a multi-resistant bacterial model [39]. However, this reduction is explained by the ability of Pb to accumulate in polyphosphate inclusions [40].…”

Individual competence predominates over host nutritional status in Arabidopsis root exudate-mediated bacterial enrichment in a combination of four Burkholderiaceae species

“…Second, total phenolic content was measured through the Fast Blue BB method [ 43 ]. Third, total carbohydrate levels were measured through a phenol-sulfuric acid method [ 44 ], which has already been used to measure carbohydrates on plant exudates [ 17 ]. Exudate pool samples were diluted at 1:1000 to fit the calibration curves.…”

“…For example, C. pinatubonensis JMP134 degrades a variety of aromatic compounds [14], several of them components of PRE [7,8], with these catabolic abilities playing a role in plant colonization and plant protection [15]. C. metallidurans CH34, with tolerance to a wide range of metals [16], can promote growth and protect Arabidopsis from copper effects [17], and C. taiwanensis LMG19424 fixes nitrogen in nodulating plants [18]. In turn, P. phytofirmans PsJN is a well-known plant growth-promoting bacterium able to establish rhizospheric and endophytic colonization on several plants, including Arabidopsis [19][20][21][22].…”