Cell wall invertase improves grain nutrition via regulating sugar and hormone metabolism gene expression in transgenic soybean

Abstract Background and Aims Cell wall invertases have multiple roles in plant growth and development, yet their biological functions in seed oil production are still not understood. Methods In the present study, the Oryza sativa (rice) cell wall invertase gene OsGIF1 (GRAIN INCOMPLETE FILLING 1) was ectopically expressed in Glycine max (soybean), and its functions in grain yield and seed nutrition were investigated. Key Results We found that constitutive expression of OsGIF1 significantly improved biomass production, grain yield and seed nutrition in transgenic plants. The contents of protein and starch were significantly increased without dramatic alteration in the content of oil in the seeds of transgenic plants. In addition, the contents of histidine, tryptophan, asparagine, glutamine, palmitic acid and linoleic acid were increased, whereas the contents of oleic acid and linolenic acid were decreased. Further transcriptomic analyses in transgenic plants showed that genes associated with sugar and hormone metabolism were dramatically upregulated. Conclusions Our findings offer direct evidence for the potential usage of this gene in the genetic breeding of oil crops with improved grain yield and nutrition.