GmSTF accumulation mediated by DELLA protein GmRGAs contributes to coordinating light and gibberellin signaling to reduce plant height in soybean

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.

The GmSTF1/2–GmBBX4 negative feedback loop acts downstream of blue-light photoreceptors to regulate isoflavonoid biosynthesis in soybean

Isoflavonoids,secondary metabolites derived from the phenylalanine pathway,are predominantly bio-synthesized in legumes,especially soybean(Glycine max).They are not only essential for plant responses to biotic and abiotic stresses but also beneficial to human health.In this study,we report that light signaling controls isoflavonoid biosynthesis in soybean.Blue-light photoreceptors(GmCRY1s,GmCRY2s,GmPHOT1s,and GmPHOT2s)and the transcription factors GmSTF1 and GmSTF2 promote isoflavonoid accumulation,whereas the E3 ubiquitin ligase GmCOP1b negatively regulates isoflavonoid biosynthesis.GmPHOT1s and GmPHOT2s stabilize GmSTF1/2,whereas GmCOP1b promotes the degradation of these two proteins in soybean.GmSTF1/2 regulate the expression of approximately 27.9%of the genes involved in soybean isoflavonoid biosynthesis,including GmPAL2.1,GmPAL2.3,and GmUGT2.They also repress the expression of GmBBX4,a negative regulator of isoflavonoid biosynthesis in soybean.In addition,GmBBX4 physically interacts with GmSTF1 and GmSTF2 to inhibit their transcriptional activation activity toward target genes related to isoflavonoid biosynthesis.Thus,GmSTF1/2 and GmBBX4 form a negative feedback loop that acts downstream of photoreceptors in the regulation of isoflavonoid biosynthesis.Our study provides novel insights into the control of isoflavonoid biosynthesis by light signaling in soybean and will contribute to the breeding of soybean cultivars with high isoflavonoid content through genetic and metabolic engineering.