Overexpression of a Thioredoxin-Protein-Encoding Gene, MsTRX, from Medicago sativa Enhances Salt Tolerance to Transgenic Tobacco

Abstract

Thioredoxin (TRX) is a small molecule protein that participates in the redox process and plays a decisive role in various functions of plants. However, the role of TRX in Medicago sativa (alfalfa), a widely cultivated perennial herb of legume, is still poorly understood. Here, we isolated MsTRX from alfalfa and determined the characteristics in improving salt tolerance by assaying the phenotype and physiological changes and the expression of stress-response genes in transgenic tobacco. The expression of MsTRX was similar in alfalfa roots, leaves, and inflorescences, and was downregulated in response to cold, drought, and salt treatment. The overexpression of MsTRX in tobacco promoted the accumulation of soluble sugar (SS) and proline; enhanced the activity of peroxidase (POD); and induced the upregulation of beta-amylase 1 (BAM1), lipid-transfer protein 1 (LTP1), candidate signal molecules/sensor relay proteins (CBSX3), superoxide dismutase [Cu-Zn] (Cu/Zn-SOD), superoxide dismutase [Mn] (Mn-SOD), protein gamma response 1 (GR1), dehydrin DHN1-like (ERD10B), and serine/threonine-protein kinase (SnRK2), as well as the downregulation of phyB activation-tagged suppressor1 (BAS1) and serine/threonine-protein kinase that phosphorylates LHCII protein 7 (STN7) under salt stress. These results indicated that MsTRX improves salt tolerance via maintaining osmotic homeostasis, scavenging reactive oxygen species (ROS), and regulating the transcription of stress-response genes in plants. In our study, we provided a new understanding of how MsTRX improves salt stress in plants and how MsTRX can be included in future breeding programs to improve salt tolerance in alfalfa.

Physiological and Transcriptional Responses of Apocynum venetum to Salt Stress at the Seed Germination Stage

“…For example, the trehalose-6-phosphate synthase ( TPS ) gene plays a critical role in Citrullus lanatus ’ response to salt stress [ 64 ]; the OsGolS1 gene is significantly up-regulated in Oryza sativa ssp. japonica under salt stress [ 65 ]; and the overexpression of MsTRX in tobacco induced the upregulation of beta-amylase 1 ( BAM1 ) under salt stress [ 66 ]. In this study, 79 genes were directly associated with soluble sugar and protein metabolism, and 41 genes participate in soluble sugar metabolism.…”

Members of the Capsicum annuum CaTrxh Family Respond to High Temperature and Exhibit Dynamic Hetero/Homo Interactions

“…The Trxh genes have been reported to be involved in oxidative tolerance in abiotic stress [33,34]. We therefore investigated the gene expression of the CaTrxh family in response to cold and heat stresses.…”

Transcriptomic Analysis of Cucumis hystrix and the Functional Identification of ChTrxh under NaCl Stress

“…In leaves, we identified 159 DEGs encoding a transcription factor; among them, 45 were down-regulated and 114 were up-regulated. The predominantly expressed transcription factors were the ethylene-responsive transcription factor (ERF) (39), the basic helix-loophelix (bHLH) (18), MYB (16), WRKY (23), the heat stress transcription factor (10), and GATA (4) families. In roots, we identified 138 DEGs encoding a transcription factor; among these, 55 were down-regulated and 83 were up-regulated.…”

“…These DEGs were further categorized into glutathione S-transferase (GST) family proteins (12), superoxide dismutase (SOD, 2), peroxidase (POD, 15), glutaredoxin (7), thioredoxin superfamily protein isoform and thioredoxin-like protein (4), and 1-Cys peroxiredoxin (1) in leaves. In the root, they were categorized into GST family proteins (25), SOD (3, up-regulated), POD (23), glutathione peroxidase (4, up-regulated), L-ascorbate peroxidase (1, up-regulated), glutathione reductase (1, up-regulated), and glutaredoxin (2, up-regulated) (Table S5, Figure 5B).…”