DNA Demethylase ROS1 Interferes with DNA Methylation and Activates Stress Response Genes in Plants Infected with Beet Severe Curly Top Virus

DNA methylation is one mechanism of epigenetic regulation in plants. Small interfering RNAs (siRNAs) targeted endogenous genes and caused the promoters to be hypermethylated, namely RNA-directed DNA methylation (RdDM). Repressor of silencing 1 (ROS1) is an active DNA demethylase involved in the regulation of DNA methylation. This study indicates that ROS1-mediated DNA demethylation plays important roles in regulating the expression of these stress response genes and in response to biotic stresses. Further experiments confirmed that the expression level of the <i>ROS1</i> gene was significantly upregulated in <i>A. thaliana</i> plants infected with <i>beet severe curly top virus</i> (BSCTV). Moreover, the DNA sequencing results demonstrated that ROS1 interferes with DNA methylation of repeat regions in the promoters of <i>ACD6</i>, <i>GSTF14</i>, and <i>ACO3</i> in <i>A. thaliana</i> plants infected with BSCTV. These findings reveal the epigenetic mechanisms by which ROS1 regulates the expression of the stress response genes, thereby improving the adaptability of plants to biotic stresses.