Identification and expression of the AREB/ABF/ABI5 subfamily genes in chickpea and lentil reveal major players involved in ABA-mediated defense response to drought stress.

Main conclusion: This study identified and evaluated the expression of the AREB/ABF/ABI5 subfamily genes in chickpea and lentil, and revealed the major players involved in defense response to PEG-induced drought stress. Abscisic acid (ABA)-responsive element-binding protein/ABRE-binding factor/ABA-INSENSITIVE 5 (AREB/ABF/ABI5) subfamily proteins are major players in the ABA-mediated signaling pathway triggered by multiple stresses. AREB/ABF/ABI5 subfamily proteins belong to the basic-leucine zipper transcription factors that regulate the expression of several downstream defense genes to abiotic and biotic stresses. This protein set is highly targeted when trying to understand plant defense against abiotic stress or to improve plant tolerance to drought, cold, and salinity stresses. However, there is still very little information available about the genes of the AREB/ABF/ABI5 subfamily in chickpea and lentil. Herein, 8 chickpea and 9 lentil genes of the AREB/ABF/ABI5 subfamily were identified based on sequence analysis, and their expression levels were tested in a polyethylene glycol-induced drought experiment (20% PEG in Hoagland solution) using real-time RT-PCR and metadata analysis. Sequence analysis showed that members of this subfamily are highly conserved among themselves and with their orthologous genes in other closely related plant species. Overall, sequence data suggested that these genes may possess close or overlapping biological roles in regulating the transcription of abiotic stress-related defense genes. The meta-analysis from RNA-Seq datasets of unstressed plants showed that some members of this gene subfamily have a tissue-specific expression in both chickpea and lentil. Drought-contrasting chickpea and lentil cultivars showed that most AREB/ABF/ABI5 genes are modulated by PEG-induced drought. Furthermore, AREB/ABF/ABI5 genes had also a tendency for higher expression as cultivar tolerance increases. Therefore, this study identified the AREB/ABF/ABI5 subfamily genes in chickpea and lentil, and provides a comprehensive characterization of these members to support further focused research.