Enhanced Cd-Accumulation in Typha latifolia by Interaction with Pseudomonas rhodesiae GRC140 under Axenic Hydroponic Conditions

Abstract

The <i>Typha</i> genus comprises plant species extensively studied for phytoremediation processes. Recently, <i>Pseudomonas rhodesiae</i> GRC140, an IAA-producing bacterium, was isolated from <i>Typha latifolia</i> roots. This bacterium stimulates the emergence of lateral roots of <i>Arabidopsis thaliana</i> in the presence and absence of cadmium. However, the bacterial influence on cadmium accumulation by the plant has not been determined. Moreover, the <i>P. rhodesiae</i> GRC140 effect in Cd phytoextraction by <i>T. latifolia</i> remains poorly understood. In this work, an axenic hydroponic culture of <i>T. latifolia</i> was established. The plants were used to evaluate the effects of cadmium stress in axenic plants and determine the effects of <i>P. rhodesiae</i> GRC140 and exogenous indole acetic acid (IAA) on Cd tolerance and Cd uptake by <i>T. latifolia</i>. Biomass production, total chlorophyll content, root electrolyte leakage, catalase activity, total glutathione, and Cd content were determined. The results showed that Cd reduces shoot biomass and increases total glutathione and Cd content in a dose-dependent manner in root tissues. Furthermore, <i>P. rhodesiae</i> GRC140 increased Cd translocation to the shoots, while IAA increased the Cd accumulation in plant roots, indicating that both treatments increase Cd removal by <i>T. latifolia</i> plants. These results indicate that axenic plants in hydroponic systems are adequate to evaluate the Cd effects in plants and suggest that <i>T. latifolia</i> phytoextraction abilities could be improved by <i>P. rhodesiae</i> GRC140 and exogenous IAA application.