Effects of StP5CS gene overexpression on nodulation and nitrogen fixation of vegetable soybean under salt stress conditions

Using a quartz sand culture, comparisons were made between the T5 homozygous transgenic lines (HTLs) that overexpress StP5CS (GenBank accession number: JN606861) and their wild-type (WT) host cultivar to examine the differences in the growth and development traits, the concentrations of proline in vegetable soybean [Glycine max (L.) Merrill] under salt stress conditions. Moreover, the relative expression levels of two glutamine synthetase-related genes (GmGS1â1, GmGS1â2), two nodulation-related genes (GmENOD40-1, GmENOD40-2), and one leghemoglobin gene (GmLba) were also measured. The purpose of this research was to provide a theoretical basis for elucidating the mechanisms of nodulation and nitrogen fixation in the roots of transgenic plants under salt stress conditions. Compared with WT plants, the plant height and seed weight per plant of T5 HTLs significantly increased, and the contents of proline in various tissues of T5 HTLs were also significantly elevated. Quantitative real-time PCR (qRT-PCR) analysis indicated that the expression levels of GmGS1â1, GmGS1â2, GmENOD40-1, GmENOD40-2, and GmLba were significantly increased in T5 HTLs under salt stress conditions. These results indicate that the overexpression of StP5CS in T5 HTLs enhanced growth, nodulation and nitrogen fixation in transgenic vegetable soybean under salt stress conditions.