Methylisothiazolinone pollution inhibited root stem cells and regeneration through auxin transport modification in Arabidopsis thaliana

Methylisothiazolinone (MIT) is a widely used preservative and biocide to prevent product degradation, yet its potential impact on plant growth remains poorly understood. In this study, we investigated MIT's toxic effects on Arabidopsis thaliana root growth. Exposure to MIT significantly inhibited Arabidopsis root growth, associated with reduced root meristem size and root meristem cell numbers. We explored the polar auxin transport pathway and stem cell regulation as key factors in root meristem function. Our findings demonstrated that MIT suppressed the expression of the auxin efflux carrier PIN1 and major root stem cell regulators (PLT1, PLT2, SHR, and SCR). Additionally, MIT hindered root regeneration by downregulating the quiescent center (QC) marker WOX5. Transcriptome analysis revealed MIT-induced alterations in gene expression related to oxidative stress, with physiological experiments confirming elevated reactive oxygen species (ROS) levels and increased cell death in root tips at concentrations exceeding 50 μM. In summary, this study provides critical insights into MIT's toxicity on plant root development and regeneration, primarily linked to modifications in polar auxin transport and downregulation of genes associated with root stem cell regulation.