Soybean (Glycine max) WRINKLED1 transcription factor, GmWRI1a, positively regulates seed oil accumulation.

Soybean is the world's most important leguminous crop producing high-quality protein and oil. Elevating oil accumulation in soybean seed is always many researchers' goal. WRINKLED1 (WRI1) encodes a transcription factor of the APETALA2/ethylene responsive element-binding protein (AP2/EREBP) family that plays important roles during plant seed oil accumulation. In this study, we isolated and characterized three distinct orthologues of WRI1 in soybean (Glycine max) that display different organ-specific expression patterns, among which GmWRI1a was highly expressed in maturing soybean seed. Electrophoretic mobility shift assays and yeast one-hybrid experiments demonstrated that the GmWRI1a protein was capable of binding to AW-box, a conserved sequence in the proximal upstream regions of many genes involved in various steps of oil biosynthesis. Transgenic soybean seeds overexpressing GmWRI1a under the control of the seed-specific napin promoter showed the increased total oil and fatty acid content and the changed fatty acid composition. Furthermore, basing on the activated expressions in transgenic soybean seeds and existence of AW-box element in the promoter regions, direct downstream genes of GmWRI1a were identified, and their products were responsible for fatty acid production, elongation, desaturation and export from plastid. We conclude that GmWRI1a transcription factor can positively regulate oil accumulation in soybean seed by a complex gene expression network related to fatty acid biosynthesis.

Integrated examination of the transcriptome and metabolome of the gene expression response and metabolite accumulation in soybean seeds for seed storability under aging stress.

Soybean quality and production are determined by seed viability. A seed's capacity to sustain germination via dry storage is known as its seed life. Thus, one of the main objectives for breeders is to preserve genetic variety and gather germplasm resources. However, seed quality and germplasm preservation have become significant obstacles. In this study, four artificially simulated aging treatment groups were set for 0, 24, 72, and 120 hours. Following an aging stress treatment, the transcriptome and metabolome data were compared in two soybean lines with notable differences in seed vigor-R31 (aging sensitive) and R80 (aging tolerant). The results showed that 83 (38 upregulated and 45 downregulated), 30 (19 upregulated and 11 downregulated), 90 (52 upregulated and 38 downregulated), and 54 (25 upregulated and 29 downregulated) DEGs were differentially expressed, respectively. A total of 62 (29 upregulated and 33 downregulated), 94 (49 upregulated and 45 downregulated), 91 (53 upregulated and 38 downregulated), and 135 (111 upregulated and 24 downregulated) differential metabolites accumulated. Combining the results of transcriptome and metabolome investigations demonstrated that the difference between R31 and R80 responses to aging stress was caused by genes related to phenylpropanoid metabolism pathway, which is linked to the seed metabolite caffeic acid. According to this study's preliminary findings, the aging-resistant line accumulated more caffeic acid than the aging-sensitive line, which improved its capacity to block lipoxygenase (LOX) activity. An enzyme activity inhibition test was used to demonstrate the effect of caffeic acid. After soaking seeds in 1 mM caffeic acid (a LOX inhibitor) for 6 hours and artificially aging them for 24 hours, the germination rates of the R31 and R80 seeds were enhanced. In conclusion, caffeic acid has been shown to partially mitigate the negative effects of soybean seed aging stress and to improve seed vitality. This finding should serve as a theoretical foundation for future research on the aging mechanism of soybean seeds.