Search

The StP5CS (GenBank accession number: JN606861) T6 homozygous transgenic lines (HTLs) of vegetable soybean [Glycine max (L.) Merrill] were grown using vermiculite pot culture to determine whether StP5CS overexpression would enhance nodulation and symbiotic nitrogen fixation (SNF) in two T6 HTLs (17W-1, 17W-2) under drought conditions. The growth performance, nodule development and seed weight of T6 HTLs were significantly better than those of wild type (WT) plants. The proline levels in various tissues of T6 HTLs were higher than WT plants. The concentrations of total ureide, total N, leghemoglobin (Lb) and the activity of glutamine synthetase (GS, EC 6.3.1.2) in the T6 HTLs were significantly increased. Moreover, the relative expression levels of five key nodulation- and SNF-associated genes (i.e., GmENOD40-1, GmENOD40-2, GmLba, GmGS1β1 and GmGS1β2) were significantly higher in T6 HTLs. In conclusion, overexpression of StP5CS enhances nodulation and SNF in transgenic vegetable soybean under drought stress conditions. [ABSTRACT FROM AUTHOR]

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 (GmGS1α1, GmGS1α2), 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 GmGS1α1, GmGS1α2, 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. [ABSTRACT FROM AUTHOR]

Two cultivars contrasting in NaCl tolerance were used to investigate the possible involvement of polyamines in salt tolerant mechanisms in roots of vegetable soybean. 'Tianfeng', the salt tolerant cultivar exhibited overall higher contents of free, soluble conjugated and insoluble bound forms of polyamines (putrescine, spermidine and spermine) except for free spermidine over the salt sensitive line during the course of NaCl treatment for 15 days. Consistent with this observation, arginine decarboxylase, the essential enzyme of polyamines biosynthesis and two enzymes catalyzing breakdown of polyamines were differentially regulated between the two cultivars. Antioxidant enzymes downstream to the polyamines signaling globally showed higher activity in 'Tianfeng', resulting in lower contents of reactive oxygen species and malondialdehyde subsequently. These results taken together indicate that higher levels of polyamines may be important in conferring enhanced salt tolerance in roots of vegetable soybean by activating antioxidant enzymes and, therefore, attenuating oxidative damage. [ABSTRACT FROM AUTHOR]