Genome-Wide Identification and Transcriptional Analysis of AP2/ERF Gene Family in Pearl Millet (Pennisetum glaucum)

Abstract

The apetala2/ethylene response factor (AP2/ERF) gene family plays a crucial role in regulating plant growth and development and responding to different abiotic stresses (e.g., drought, heat, cold, and salinity). However, the knowledge of the ERF family in pearl millet remains limited. Here, a total of 167 high-confidence <i>PgERF</i> genes are identified and divided into five subgroups based on gene-conserved structure and phylogenetic analysis. Forty-one pairs of segmental duplication are found using collinear analysis. Nucleotide substitution analysis reveals these duplicated pairs are under positive purification, indicating they are actively responding to natural selection. Comprehensive transcriptomic analysis reveals that <i>PgERF</i> genesare preferentially expressed in the imbibed seeds and stem (tilling stage) and respond to heat, drought, and salt stress. Prediction of the <i>cis</i>-regulatory element by the PlantCARE program indicates that <i>PgERF</i> genes are involved in responses to environmental stimuli. Using reverse transcription quantitative real-time PCR (RT-qPCR), expression profiles of eleven selected <i>PgERF</i> genes are monitored in various tissues and during different abiotic stresses. Transcript levels of each <i>PgERF</i> gene exhibit significant changes during stress treatments. Notably, the <i>PgERF7</i> gene is the only candidate that can be induced by all adverse conditions. Furthermore, four <i>PgERF</i> genes (i.e., <i>PgERF22</i>, <i>PgERF37</i>, <i>PgERF88</i>, and <i>PgERF155</i>) are shown to be involved in the ABA-dependent signaling pathway. These results provide useful bioinformatic and transcriptional information for understanding the roles of the pearl millet <i>ERF</i> gene family in adaptation to climate change.