Transcriptome analysis revealed that Arabidopsis model plant invokes the activation of heat shock proteins and ER stress response against cesium stress

Cesium (Cs) toxicity has deleterious effects on plant growth and development. However, the molecular mechanism of the toxic effect of Cs on plants has been poorly understood. To obtain insights into the molecular events occurring in plants under Cs stress, we performed a comparative transcriptomic analysis between control and Cs-treated plants via RNA-seq. We identified 183 differentially expressed genes (141 upregulated and 42 downregulated) under Cs stress (1.5 mM CsCl). Gene ontology (GO) analysis using differentially expressed genes in Cs stress indicated that Cs triggered plant stress signaling pathways like reactive oxygen species (i.e., hydrogen peroxide). Further KEGG and MapMan metabolic pathway analyses revealed that many abiotic/biotic stress signaling pathways were highly induced. In particular, heat shock protein family genes were substantially induced upon exposure to Cs stress. We investigated the root growth of several knockout mutants of heat shock protein family genes and found that heat stress response was compromised in these mutants compared to wild type plants. It suggested that heat shock protein genes including HSP17s, HSP23s, HSP101, and HSFA2 proteins are deployed upon exposure to Cs for plant stress tolerance. Our study provided novel insights into the molecular events occurring in Cs-stressed plants.