*Article* **Genome-Wide Identification of Maize Protein Arginine Methyltransferase Genes and Functional Analysis of** *ZmPRMT1* **Reveal Essential Roles in** *Arabidopsis* **Flowering Regulation and Abiotic Stress Tolerance**

**Qiqi Ling † , Jiayao Liao † , Xiang Liu, Yue Zhou and Yexiong Qian \***

> Anhui Provincial Key Laboratory of Conservation and Exploitation of Important Biological Resources, College of Life Sciences, Anhui Normal University, Wuhu 241000, China

**\*** Correspondence: qyx2011@ahnu.edu.cn; Tel.: +86-55-3386-9297

† These authors contributed equally to this work.

**Abstract:** Histone methylation, as one of the important epigenetic regulatory mechanisms, plays a significant role in growth and developmental processes and stress responses of plants, via altering the methylation status or ratio of arginine and lysine residues of histone tails, which can affect the regulation of gene expression. Protein arginine methyltransferases (PRMTs) have been revealed to be responsible for histone methylation of specific arginine residues in plants, which is important for maintaining pleiotropic development and adaptation to abiotic stresses in plants. Here, for the first time, a total of eight *PRMT* genes in maize have been identified and characterized in this study, named as *ZmPRMT1-8*. According to comparative analyses of phylogenetic relationship and structural characteristics among *PRMT* gene family members from several representative species, all maize 8 PRMT proteins were categorized into three distinct subfamilies. Further, schematic structure and chromosome location analyses displayed evolutionarily conserved structure features and an unevenly distribution on maize chromosomes of *ZmPRMT* genes, respectively. The expression patterns of *ZmPRMT* genes in different tissues and under various abiotic stresses (heat, drought, and salt) were determined. The expression patterns of *ZmPRMT* genes indicated that they play a role in regulating growth and development and responses to abiotic stress. Eventually, to verify the biological roles of *ZmPRMT* genes, the transgenic *Arabidopsis* plants overexpressing *ZmPRMT1* gene was constructed as a typical representative. The results demonstrated that overexpression of *ZmPRMT1* can promote earlier flowering time and confer enhanced heat tolerance in transgenic *Arabidopsis*. Taken together, our results are the first to report the roles of *ZmPRMT1* gene in regulating flowering time and resisting heat stress response in plants and will provide a vital theoretical basis for further unraveling the functional roles and epigenetic regulatory mechanism of *ZmPRMT* genes in maize growth, development and responses to abiotic stresses.

**Keywords:** histone methylation; protein arginine methyltransferase; *Zea mays* L.; abiotic stress; functional analysis
