miR397-LACs mediated cadmium stress tolerance in Arabidopsis thaliana

Abstract

Cadmium (Cd) is a non-essential heavy metal, assimilated in plant tissue with other nutrients, disturbing the ions' homeostasis in plants. The plant develops different mechanisms to tolerate the hazardous environmental effects of Cd. Recently studies found different miRNAs that are involved in Cd stress. In the current study, miR397 mutant lines were constructed to explore the molecular mechanisms of miR397 underlying Cd tolerance. Compared with the genetically modi ed line of overexpressed miR397 (arti cial miR397, amiR397), the lines of downregulated miR397 (Short Tandem Target Mimic miR397, STTM miR397) showed more substantial Cd tolerance with higher chlorophyll a & b, carotenoid and lignin content than amiR397. ICP-OES revealed higher cell wall Cd and low total Cd levels in STTM miR397 than in the wild-type and amiR397 plants. Further, the STTM plants produced fewer reactive oxygen species (ROS) and lower activity of antioxidants enzymes (e.g., catalase [CAT], malondialdehyde [MDA]) compared with amiR397 and wild-type plants after stress, indicating that silencing the expression of miR397 can reduce oxidative damage. In addition, the different family transporters' gene expression was much higher in the amiR397 plants than in the wild type and STTM miRNA397. Our results suggest that miR397 plays a role in Cd tolerance in Arabidopsis thaliana. Overexpression of miR397 could decrease Cd tolerance in plants by regulating the expression of LAC 2/4/17, changing the lignin content, which may play an important role in inducing different stress-tolerant mechanisms and protecting the cell from a hazardous condition. This study provides a basis to elucidate the functions of miR397 and the Cd stress tolerance mechanism in Arabidopsis thaliana.

microRNAs: Key Regulators in Plant Responses to Abiotic and Biotic Stresses via Endogenous and Cross-Kingdom Mechanisms

“…Cadmium is a particularly persistent trace metal and a hazardous environmental pollutant [47] that is not essential for key plant metabolic or growth processes [48]. Therefore, Ali et al constructed Arabidopsis thaliana miR397 mutant lines to investigate the molecular mechanisms responsible for the potential relationship between cadmium tolerance and miR397 expression [49]. They found that overexpressing miR397 alters lignin content and reduces cadmium tolerance by regulating laccase 2, 4, and 17 expressions.…”