Seed-specific overexpression of DREB2G alters seed morphology, oil accumulation, and germination in Arabidopsis.

key messageSeed-specific overexpression of DREB2G alters seed morphology, oil accumulation, seed maturation and germination, accompanied by broad transcriptomic changes in Arabidopsis seeds. Seeds are essential for plant reproduction and are indispensable sources of vegetable oils used in food, industrial products, and biofuel production. Although dehydration-responsive element-binding (DREB) transcription factors are well known for their roles in abiotic stress responses, their functions in regulating seed traits remain poorly understood. Here, we identified the Arabidopsis transcription factor DREB2G as a regulator of multiple seed traits. Seed-specific overexpression of DREB2G (DREB2G-OE) in Arabidopsis altered seed morphology and reduced seed oil accumulation. DREB2G-OE lines also displayed accelerated seed maturation compared to wild-type (WT). RNA-sequencing analysis of developing DREB2G-OE seeds revealed substantial transcriptomic reprogramming, including increased expression of genes associated with cell-cycle regulation and cell-wall remodeling, such as EXPANSINS (EXPAs) and D-type cyclins (CYCD). Consistent with these transcriptional changes, DREB2G-OE seeds germinated more rapidly than WT seeds. Dual-luciferase assays in Nicotiana benthamiana leaves showed that DREB2G transactivated the promoters of diverse EXPA and CYCD genes, and electrophoretic mobility shift assays further demonstrated direct binding of DREB2G to a DRE-like motif in the EXPA13 promoter. Collectively, our findings reveal a regulatory role for DREB2G in coordinating seed development, maturation, and germination-associated transcriptional programs in Arabidopsis.