GmEID1 modulates light signaling through the Evening Complex to control flowering time and yield in soybean.

Abstract

Soybean (Glycine max) morphogenesis and flowering time are accurately regulated by photoperiod, which determine the yield potential and limit soybean cultivars to a narrow latitudinal range. The <i>E3</i> and <i>E4</i> genes, which encode phytochrome A photoreceptors in soybean, promote the expression of the legume-specific flowering repressor <i>E1</i> to delay floral transition under long-day (LD) conditions. However, the underlying molecular mechanism remains unclear. Here, we show that the diurnal expression pattern of <i>GmEID1</i> is opposite to that of <i>E1</i> and targeted mutations in the <i>GmEID1</i> gene delay soybean flowering regardless of daylength. GmEID1 interacts with J, a key component of circadian Evening Complex (EC), to inhibit <i>E1</i> transcription. Photoactivated E3/E4 interacts with GmEID1 to inhibit GmEID1-J interaction, promoting J degradation resulting in a negative correlation between daylength and the level of J protein. Notably, targeted mutations in <i>GmEID1</i> improved soybean adaptability by enhancing yield per plant up to 55.3% compared to WT in field trials performed in a broad latitudinal span of more than 24°. Together, this study reveals a unique mechanism in which E3/E4-GmEID1-EC module controls flowering time and provides an effective strategy to improve soybean adaptability and production for molecular breeding.