ANNOUNCEMENTS
The evolutionary success of the higher plants has been acquired through the evolution of its genes and their regulatory sequences, which is accomplished by genomic rearrangements like duplications, deletions, insertions, or substitution, and random mutations. APETALA2/ETHYLENE RESPONSIVE FACTORS (AP2/ERF) is one such family of transcription factors which possess basic structure having AP2/ERF domain and some of which have been implicated in the plant growth and development. However, little is known about the origin, evolutionary pattern, and regulation of this gene family in the plant kingdom. APL is classified into four major subfamilies i.e. ERF/DREB, AP2, RAV, and soloist. Here, we report genes encoding APL protein from different species across the plant kingdom, the origin of their conserved domain, and their evolutionary patterns contributing to the subfunctionalization of the domain. Through phylogenetic analysis, we showed that APL sequences evolved initially in the marine green algae Ostreococcus tauri which further acquired subfunctionalization through duplication and gradually evolved in different groups of plants in course evolution and remained conserved. We also report the structure of selected Arabidopsis APL (AtAPL) promoters and the pattern of Cis-regulatory elements (CREs) related to the phylogenetic distance among homologs. Insilco analysis of the AtAPL promoter region identified several CREs to be conserved in the promoters of closely related APLs, and these CREs may potentially be involved in phytohormone (cytokinin, gibberellins, and abscisic acid) signaling, tissue-specific activity (roots and seed) and signaling pathway related to plant development. Further, we cloned the promoter and developed the reporter line of an AtAPL for experimental validation of its spatiotemporal expression, which should also be helpful to understand its function. Altogether, this study reveals the origin of APL domain, the evolutionary pattern of APLs across the plant kingdom, and the distribution and conservation of Cis-elements in the promoters of AtAPLs
Keywords: Evolution; AP2/ERF; transcription factor; Arabidopsis thaliana; promoter; Cis-acting regulatory elements (CREs); in silico; Phylogeny
