AtC3H3, an Arabidopsis Non-TZF Gene, Enhances Salt Tolerance by Increasing the Expression of Both ABA-Dependent and -Independent Stress-Responsive Genes

Salinity causes widespread crop loss and prompts plants to adapt through changes in gene expression. In this study, we aimed to investigate the function of the non-tandem CCCH zinc-finger (non-TZF) protein gene <i>AtC3H3</i> in response to salt stress in <i>Arabidopsis</i>. <i>AtC3H3</i>, a gene from the non-TZF gene family known for its RNA-binding and RNase activities, was up-regulated under osmotic stress, such as high salt and drought. When overexpressed in <i>Arabidopsis</i>, <i>AtC3H3</i> improved tolerance to salt stress, but not drought stress. The expression of well-known abscisic acid (ABA)-dependent salt stress-responsive genes, namely <i>Responsive to Desiccation 29B</i> (<i>RD29B</i>), <i>RD22</i>, and <i>Responsive to ABA 18</i> (<i>RAB18</i>), and representative ABA-independent salt stress-responsive genes, namely <i>Dehydration-Responsive Element Binding protein 2A</i> (<i>DREB2A</i>) and <i>DREB2B</i>, was significantly higher in <i>AtC3H3</i>-overexpressing transgenic plants (<i>AtC3H3</i> OXs) than in wild-type plants (WT) under NaCl treatment, indicating its significance in both ABA-dependent and -independent signal transduction pathways. mRNA-sequencing (mRNA-Seq) analysis using NaCl-treated WT and <i>AtC3H3</i> OXs revealed no potential target mRNAs for the RNase function of AtC3H3, suggesting that the potential targets of AtC3H3 might be noncoding RNAs and not mRNAs. Through this study, we conclusively demonstrated that <i>AtC3H3</i> plays a crucial role in salt stress tolerance by influencing the expression of salt stress-responsive genes. These findings offer new insights into plant stress response mechanisms and suggest potential strategies for improving crop resilience to salinity stress.