Genome-Wide Analysis of FAR-RELATED SEQUENCES (FRS) Genes Related to Light Response in Soybean (Glycine max)

The <i>FAR1-RELATED SEQUENCES (FRS)</i> gene family plays a crucial role in light signaling, stress adaptation, and developmental regulation processes directly impacting crop growth and yield. This study identified 49 <i>GmFRS</i> genes unevenly distributed across 17 soybean chromosomes, phylogenetically classified into seven subgroups (I-VII), with subgroup VII forming an exclusive evolutionary subgroup alongside orthologs from Poaceae and Solanaceae. Members within each subfamily share conserved motif compositions and similar exon/intron structures. Gene duplication and selection pressure analyses revealed that the <i>GmFRS</i> family expanded primarily through WGD duplication events and then non-syntenic gene duplication, with all members evolving under purifying selection. Promoter analysis identified abundant <i>cis</i>-acting elements implicated in responses to light, phytohormones and other abiotic stimuli. Organ-/tissue-specific expression profiling demonstrated organ-preferential expression for family members, with the highest transcript levels observed in flowers (32.7%). Quantitative real-time PCR (qRT-PCR) analysis further indicated that the expression of most <i>GmFRS</i> genes is light-inducible and exhibits marked sensitivity to far-red light. This study may elucidate soybean <i>FRS</i> family functions in light signaling, development, and stress adaptation, while also providing foundational insights for molecular breeding in <i>Glycine max</i>.