Comparative analysis of the novel EF-gene family provides insights into their function as regulators of early flowering

The subject of essential genes regulating flowering and floral organ development, based on MADS-box genes, has been extensively studied in several model plants, including dicots such as Arabidopsis and snapdragon, and the monocot rice. Despite the extensive research conducted on floral organ development and the pivotal role of transcription factors such as MADS-box genes, there has been a paucity of studies exploring the influence of non-transcription factors on floral organ differentiation. The overexpression of Nicotiana tabacum early flowering 1 (NtEF1) and Nicotiana tabacum early flowering 2 (NtEF2) in tobacco has been observed to result in the transformation of stamens into petals. It is postulated that these genes exert an influence on the differentiation of floral organs and the timing of flowering. To date, studies on floral organ differentiation by single genes other than transcription factors such as the MADS-box gene have not been conducted in detail. Consequently, an analysis of NtEF1 and NtEF2 is required. In this study, we investigated and annotated high-potential EF genes in a variety of plants based on two genes in tobacco and performed a comprehensive analysis in 34 plants. Phylogenetic and gene-structure analyses enabled the entire EF-gene family to be categorized into three clades, and their genetic organization revealed the presence of motifs specific to each subfamily. Moreover, our findings suggest that the genetic architecture of this family is highly conserved despite species differences. The results of functional and RNA sequencing indicate that the candidate EF gene is likely to be a single gene involved in the regulation of floral organ development and flowering time. These results provide a genetically valuable resource by identifying orthologous genes of NtEF1 and NtEF2, which act as regulators that directly influence the timing of floral reproductive growth and organ differentiation in plants.