Identification, Characterization, and Expression Profile Analysis of the mTERF Gene Family and Its Role in the Response to Abiotic Stress in Barley (Hordeum vulgare L.)

Abstract

Plant mitochondrial transcription termination factor (mTERF) family regulates organellar gene expression (OGE) and is functionally characterized in diverse species. However, limited data are available about its functions in the agriculturally important cereal barley (<i>Hordeum vulgare</i> L.). In this study, we identified 60 <i>mTERF</i>s in the barley genome (<i>HvmTERF</i>s) through a comprehensive search against the most updated barley reference genome, Morex V2. Then, phylogenetic analysis categorized these genes into nine subfamilies, with approximately half of the <i>HvmTERF</i>s belonging to subfamily IX. Members within the same subfamily generally possessed conserved motif composition and exon-intron structure. Both segmental and tandem duplication contributed to the expansion of <i>HvmTERF</i>s, and the duplicated gene pairs were subjected to strong purifying selection. Expression analysis suggested that many <i>HvmTERF</i>s may play important roles in barley development (e.g., seedlings, leaves, and developing inflorescences) and abiotic stresses (e.g., cold, salt, and metal ion), and <i>HvmTERF21</i> and <i>HvmTERF23</i> were significant induced by various abiotic stresses and/or phytohormone treatment. Finally, the nucleotide diversity was decreased by only 4.5% for <i>HvmTERF</i>s during the process of barley domestication. Collectively, this is the first report to characterize <i>HvmTERF</i>s, which will not only provide important insights into further evolutionary studies but also contribute to a better understanding of the potential functions of <i>HvmTERF</i>s and ultimately will be useful in future gene functional studies.