Comparative Genomic Analysis of GARP Transcription Factor Family in Legumes and Identification of Stress-Responsive Candidate Genes

The GARP transcription factors have been identified for multiple biological functions throughout the life cycle of a plant. Despite of its involvement in crucial functions, systematic study of GARPs remains obscure in plants. In this study, we explored the genomic, molecular, and evolutionary perspectives of the GARP gene family in the three major leguminous plants, namely chickpea (Cicer arietinum), soybean (Glycine max), and barrel clover (Medicago truncatula). Here, we identified 53, 56, and 107 GARP genes in Cicer, Medicago, and Glycine, respectively. They were classified into four clades and two sub-clades as per phylogenetic analysis, and the result was supported by consensus motifs, domain organization, and exon-intron structures. Detailed comparative analysis indicates conservation of the GARP gene family in plants. Identification of paralogous and orthologous gene pairs revealed that the expansion of this family occurs mainly through genome duplication in legumes. Additionally, the three-dimensional structure and functional enrichment analysis indicated their major role in signaling, growth, development, and stress processes. The chickpea GARP genes were also characterized for their transcript modulation in diverse plant organs and during pathogenic stress. Differential regulation of 24 CaGARP genes was observed during Ascochyta Blight (AB) stress. Characterization of AB-responsive genes reveals an over-representation of stress and hormone-binding elements on the promoter of CaGARPs. Additionally, interactome analysis also confirms the role of GARPs in plant stress and development. Our findings not only provide a handful of stress-responsive genes but also lay the foundation for prospective functional studies of GARPs in legumes.