Towards the discovery of novel genetic component involved in stress resistance in A rabidopsis thaliana

The exposure of plants to high concentrations of trace metallic elements such as copper involves a remodeling of the root system, characterized by a primary root growth inhibition and an increase in the lateral root density. These characteristics constitute easy and suitable markers for screening mutants altered in their response to copper excess. A forward genetic approach was undertaken in order to discover novel genetic factors involved in the response to copper excess. A Cu 2+ ‐sensitive mutant named copper modified resistance1 ( cmr1 ) was isolated and a causative mutation in the CMR 1 gene was identified by using positional cloning and next‐generation sequencing. CMR 1 encodes a plant‐specific protein of unknown function. The analysis of the cmr1 mutant indicates that the CMR 1 protein is required for optimal growth under normal conditions and has an essential role in the stress response. Impairment of the CMR 1 activity alters root growth through aberrant activity of the root meristem, and modifies potassium concentration and hormonal balance (ethylene production and auxin accumulation). Our data support a putative role for CMR 1 in cell division regulation and meristem maintenance. Research on the role of CMR 1 will contribute to the understanding of the plasticity of plants in response to changing environments.