RESUMO
Sulfur is essential for plant growth, and the uptake of sulfate by plant roots is the primary source of plant sulfur. Previous studies have shown that the OAS-TL gene is a key enzyme in the sulfur metabolic pathway and regulates cysteine (Cys) synthase production. However, the interaction mechanism of the glycine max OAS-TL3 Cys synthase (OAS-TL3) gene on soybean root morphology construction and seed protein accumulation is unclear. This study shows that mutant M18 has better root growth and development, higher seed protein content, and higher methionine (Met) content in sulfur-containing amino acids than wild-type JN18. By transcriptome sequencing, the differentially expressed OAS-TL3 gene was targeted in the mutant M18 root line. The relative expression of the OAS-TL3 gene in roots, stems, and leaves during the seedling, flowering, and bulking stages of the OAS-TL3 gene overexpression lines is higher than that of the recipient material. Compared to the recipient material JN74, the enzymatic activities, Cys, and GSH contents of OAS-TL are higher in the sulfur metabolic pathway of seedling roots. The receptor material JN74 is exogenously applied with different concentrations of reduced glutathione. The results demonstrate a positive correlation between reduced glutathione on total root length, projected area, surface area, root volume, total root tip number, total bifurcation number, and total crossing number. The Met and total protein contents of sulfur-containing amino acids in soybean seeds of the OAS-TL3 gene overexpression lines are higher than those of the recipient material JN74, while the gene-edited lines show the opposite results. In conclusion, the OAS-TL3 gene positively regulates soybean root growth, root activity, and the content of Met in the seeds through the OAS-TL-Cys-GSH pathway. It breaks the limitation of other amino acids and facilitates the increase of total seed protein content. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-022-01348-y.
RESUMO
In order to study the role of GmXTH1 gene in alleviating drought stress, soybean seeds with GmXTH1 gene were transferred by T4 treated with PEG6000 concentration of 0%, 5%, 10%, and 15% respectively. The germination potential, germination rate, germination index, and other indicators were measured. The results showed that the germination potential, germination rate, and germination index of OEA1 and OEA2 strains overexpressed in T4 generation were significantly higher than those of the control material M18. After 0-day, 7-day, and 15-day drought stress, the analysis of seedling phenotypes and root-shoot of different T4 generation transgenic soybean lines showed that under stress conditions, the growth of GmXTH1 overexpression material was generally better than that of the control material M18. The growth of GmXTH1 interference expression material was generally worse than that of the control material M18, with significant differences in plant phenotypes. The root system of GmXTH1 overexpressed material was significantly developed compared with that of the control material M18. The analysis of physiological and biochemical indexes showed that the relative water content and the activity of antioxidant enzymes (superoxide dismutase and peroxidase) of GmXTH1 transgenic soybean material were significantly higher than those of the control material M18, and the accumulation of malondialdehyde was lower under the same stress conditions at seedling stage. Fluorescence quantitative PCR assay showed that the relative expression of GmXTH1 gene in transgenic soybean was significantly increased after drought stress. The results showed that the overexpression of GmXTH1 could increase the total root length, surface area, total projection area, root volume, average diameter, total cross number, and total root tip number, thereby increasing the water intake and reducing the transpiration of water content in leaves, thus reducing the accumulation of MDA and producing more protective enzymes in a more effective and prompt way, reducing cell membrane damage to improve drought resistance of soybean.
