Soybean (Glycine max (L.) Merr.), is one of the world’s most important oilseed and economic crops, yet its cell-biology-oriented gene-function studies remain hampered by low transformation efficiency and poor detection of fluorescent tags such as GFP. Researchers therefore routinely resort to heterologous systems like Arabidopsis or Nicotiana benthamiana, risking mis-localization and artifactual activity of soybean proteins and compromising physiological relevance. A robust, soybean-based platform is urgently needed. In this study, we introduce FLASH (Fluorescent Localization Assay for Subcellular in Hairy-root-derived callus protoplasts). Transgenic hairy roots expressing fluorescent proteins are bulked into callus, from which protoplasts are isolated in a single step and > 80% of cells display bright, stable fluorescence within 24 h. Using FLASH we monitored, in real time, light-induced assembly of GmCRY photobodies in both the nucleus and cytoplasm, and confirmed nuclear co-localization of GmCRY1b with STF1. FLASH offers a high-fidelity, high-throughput solution for subcellular localization, protein–protein interaction, and phase-separation studies of soybean proteins.

Plant height influences plant architecture, lodging resistance, and yield performance. It is modulated by gibberellic acid (GA) metabolism and signaling. DELLA proteins, acting as central repressors of GA signaling, integrate various environmental and hormonal signals to regulate plant growth and development in Arabidopsis. We examined the role of two DELLA proteins, GmRGAa and GmRGAb, in soybean plant height control. Knockout of these proteins led to longer internodes and increased plant height, primarily by increasing cell elongation. GmRGAs functioned under different light conditions, including red, blue, and far-red light, to repress plant height. Interaction studies revealed that GmRGAs interacted with the blue light receptor GmCRY1b. Consistent with this, GmCRY1b partially regulated plant height via GmRGAs. Additionally, DELLA proteins were found to stabilize the protein GmSTF1/2, a key positive regulator of photomorphogenesis. This stabilization led to increased transcription of GmGA2ox-7b and subsequent reduction in plant height. This study enhances our understanding of DELLA-mediated plant height control, offering Gmrgaab mutants for soybean structure and yield optimization.