Soybean (Glycine max (L.) Merr.) is one of the most important crops with economic value as a source of protein and vegetable oil for human food and animal feed. In recent years, rapidly developed genome editing techniques have shown widespread application prospects for gene function studies and for improving important agronomic traits in many crops. Therefore, it is important to establish a highly efficient method for protoplast isolation and transient expression systems in soybeans. In this study, we established an efficient method for protoplast isolation and its application to transient gene expression in Korean soybean cultivars. The protoplasts were isolated from leaves, epicotyls, hypocotyls, cotyledons, and etiolated hypocotyls using various combinations of enzyme mixtures. We found that high-quality and large amounts of protoplasts were isolated from the etiolated hypocotyls when incubated for 8 h under conditions of 0.5% cellulase, 0.5% pectinase, and 1% viscozyme. In addition, we observed a high transfection efficiency of green fluorescent protein using etiolated hypocotyl protoplasts. Taken together, our protoplast isolation and transfection method is highly efficient and can be used for gene function and molecular analysis to better understand the biological and physiological processes in soybean.

Salt stress is a significant factor limiting growth and productivity in crops. However, little is known about the response and resistance mechanism to salt stress in maize. The objective of this research was to develop an enhanced salt-tolerant silage maize by mutagenesis with gamma radiation. To generate gamma radiation-induced salt-tolerant silage maize, we irradiated a KS140 inbred line with 100 Gy gamma rays. Salt tolerance was determined by evaluating plant growth, morphological changes, and gene expression under NaCl stress. We screened 10 salt-tolerant maize inbred lines from 2,248 M₂ mutant populations and selected a line showing better growth under salt stress conditions. The selected 140RS516 mutant exhibited improved seed germination and plant growth when compared with the wild-type under salt stress conditions. Enhanced salt tolerance of the 140RS516 mutant was attributed to higher stomatal conductance and proline content. Using whole-genome re-sequencing analysis, a total of 328 single nucleotide polymorphisms and insertions or deletions were identified in the 140RS516 mutant. We found that the expression of the genes involved in salt stress tolerance, ABP9, CIPK21, and CIPK31, was increased by salt stress in the 140RS516 mutant. Our results suggest that the 140RS516 mutant induced by gamma rays could be a good material for developing cultivars with salt tolerance in maize.