Photoperiod is an important environmental cue. Plants can distinguish the seasons and flower at the right time through sensing the photoperiod. Soybean is a sensitive short-day crop, and the timing of flowering varies greatly at different latitudes, thus affecting yields. Soybean cultivars in high latitudes adapt to the long day by the impairment of two phytochrome genes, PHYA3 and PHYA2 , and the legume-specific flowering suppressor, E1 . However, the regulating mechanism underlying phyA and E1 in soybean remains largely unknown. Here, we classified the regulation of the E1 family by phyA2 and phyA3 at the transcriptional and posttranscriptional levels, revealing that phyA2 and phyA3 regulate E1 by directly binding to LUX proteins, the critical component of the evening complex, to regulate the stability of LUX proteins. In addition, phyA2 and phyA3 can also directly associate with E1 and its homologs to stabilize the E1 proteins. Therefore, phyA homologs control the core flowering suppressor E1 at both the transcriptional and posttranscriptional levels, to double ensure the E1 activity. Thus, our results disclose a photoperiod flowering mechanism in plants by which the phytochrome A regulates LUX and E1 activity.

Light functions as the primary environmental stimulus and brassinosteroids (BRs) as important endogenous growth regulators throughout the plant lifecycle. Photomorphogenesis involves a series of vital developmental processes that require the suppression of BR-mediated seedling growth, but the mechanism underlying the light-controlled regulation of the BR pathway remains unclear. Here, we reveal that nuclear factor YC proteins (NF-YCs) function as essential repressors of the BR pathway during light-controlled hypocotyl growth in Arabidopsis thaliana. In the light, NF-YCs inhibit BR biosynthesis by directly targeting the promoter of the BR biosynthesis gene BR6ox2 and repressing its transcription. NF-YCs also interact with BIN2, a critical repressor of BR signaling, and facilitate its stabilization by promoting its Tyr200 autophosphorylation, thus inhibiting the BR signaling pathway. Consistently, loss-of-function mutants of NF-YCs show etiolated growth and constitutive BR responses, even in the light. Our findings uncover a dual role of NF-YCs in repressing BR biosynthesis and signaling, providing mechanistic insights into how light antagonizes the BR pathway to ensure photomorphogenic growth in Arabidopsis.

The AGC protein kinase family plays a crucial role in regulating plant growth, immunity, and cell death, as well as responses to abiotic stresses such as salt-induced stress, which impact plant development and productivity. While the functions of AGC kinases have been thoroughly studied in model plants such as Arabidopsis thaliana, their roles in soybeans (Glycine max) remain poorly understood. In this study, we identified 69 AGC kinase genes in soybeans, which are unevenly distributed across 19 chromosomes and classified into five subfamilies: PDK1, AGCVI, AGCVII, AGCVIII, and AGC (other). Each subfamily shares similar exon–intron structures and specific motifs. Gene duplication and selection pressure analyses revealed that the GmAGC gene family is primarily expanded through segmental or whole-genome duplication, with all genes undergoing purifying selection during evolution. Promoter analysis identified numerous cis-regulatory elements associated with light, hormonal, and abiotic stress responses, including salt stress. The gene expression analysis demonstrated tissue-specific patterns, with the highest expression levels found in roots (19.7%). Among the 54 GmAGC genes analyzed using RT-qPCR, significant changes in expression were observed in the roots and leaves treated with sodium chloride, with most genes showing increased expression. These results illustrate the critical role of the soybean AGC kinase gene family in regulating responses to salinity stress. Our findings suggest that targeting specific GmAGC genes may enhance soybean resistance to salt toxicity, offering valuable insights for future crop improvement strategies.

Plant Cell, doi: https://doi.org/10.1093/plcell/koab112; Vol. 33, pp. 2360–2374

The FAR1-RELATED SEQUENCES (FRS) 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 GmFRS 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 GmFRS family expanded primarily through WGD duplication events and then non-syntenic gene duplication, with all members evolving under purifying selection. Promoter analysis identified abundant cis-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 GmFRS genes is light-inducible and exhibits marked sensitivity to far-red light. This study may elucidate soybean FRS family functions in light signaling, development, and stress adaptation, while also providing foundational insights for molecular breeding in Glycine max.