Eutrema EsMYB90 Gene Improves Growth and Antioxidant Capacity of Transgenic Wheat Under Salinity Stress

Abstract

The ectopic expression of the EsMYB90 transcription factor gene from halophytic Eutrema salsugineum has been reported to enhance the level of anthocyanin and other flavonoid metabolites in transgenic tobacco. In this study, the wheat JW1 overexpressing EsMYB90 showed longer roots and higher fresh weight than that in wild type (WT) under salt stress. In addition, the transgenic wheat plants displayed significantly higher peroxidase (POD) and glutathione S-transferase (GST) activity, as well as markedly lower malondialdehyde (MDA) content than that of the WT during salt stress conditions. The analysis of histochemical staining and H2O2 level indicated that the accumulation of reactive oxygen species (ROS) was significantly lower in the roots of transgenic wheat plants compared to the WT under salt stress. Transcriptome analysis revealed that the EsMYB90 gene affected the expression of considerable amounts of stress-related genes that were involved in phenylpropanoid biosynthesis and antioxidant activity in transgenic plants subjected to NaCl treatment. Importantly, the significantly upregulated expression genes in transgenic wheat under salt stress were mainly associated with the antioxidative enzymes POD and GST encoding genes compared with the WT. Furthermore, EsMYB90 is suggested to bind with the MYB-binding elements of pTaANS2 and pTaDFR1 by dual luciferase assay, to activate the transcription of TaANS2 and TaDFR1 genes that are encoding key enzymes of anthocyanin biosynthesis in transgenic wheat plants. All the results indicated that, under salt stress, the EsMYB90 gene plays a crucial role in preventing wheat seedlings from oxidative stress damage via enhancing the accumulation of non-enzymatic flavonoids and activities of antioxidative enzymes, which suggested that EsMYB90 is an ideal candidate gene for the genetic engineering of crops.

The Role of Anthocyanins in Plant Tolerance to Drought and Salt Stresses

“…Also, EsMYB90 up-regulated a wide range of genes related to phenylpropanoid biosynthesis and antioxidant activity in transgenic plants subjected to NaCl treatment. Particularly, EsMYB90 bonded with the MYB-binding elements on the promoters of TaANS2 and TaDFR1 genes, thus activating their transcription and promoting anthocyanin biosynthesis in transgenic wheat plants [75].…”

“…The overexpression of MYB112 caused up-regulation of biosynthesis genes (DFR and ANS) and TFs (MYB114, MYB7, MYB32, and PAP1) associated with anthocyanin production, while down-regulated TFs involved in flavonol biosynthesis (MYB12 and MYB111) thus resulted in increased anthocyanin accumulation [77]. on the promoters of TaANS2 and TaDFR1 genes, thus activating their transcription and promoting anthocyanin biosynthesis in transgenic wheat plants [75]. Taxonomic affiliation: Ta (Triticum aestivum L.); Md (Malus × domestic); Es (Eutrema salsugineum (Pall.)…”

Candidate Genes Associated with Abiotic Stress Response in Plants as Tools to Engineer Tolerance to Drought, Salinity and Extreme Temperatures in Wheat: An Overview

“…So, wheat lines overexpressing the GmDREB [ 58 ], AtDREB1A [ 60 ], GhDREB [ 62 ], TaERF3 [ 65 ], SNAC1 [ 67 ] and TaASR1-D [ 71 ] genes were found to be more tolerant not only to drought but also to salinity ( Table 2 ). Improved tolerance to salt stress was also achieved by overexpressing the wheat TabZIP15 gene [ 101 ], encoding a bZIP transcription factor, as well as the Eutrema salsugineum EsMYB90 gene [ 102 ] and the wheat TaMYB86B gene [ 103 ] encoding MYB transcription factors ( Table 2 ). When exposed to high salt levels, the physiological, biochemical and molecular mechanisms observed in all these transgenic lines were similar to those observed under drought stress conditions, that is the upregulation of ABA- and abiotic stress-responsive genes, the accumulation of osmolytes and the activation of the antioxidant enzyme system, which resulted in lower ROS accumulation and reduced oxidative damage to membranes, and better growth performance ( Table 2 ).…”

Insights into Salinity Tolerance in Wheat

“…The R2R3-MYB is the largest subfamily in the plant, encompassing 223 genes, including 8 genes responsive to salt stress in wheat [82]. Various MYB TFs such as TaMBY344, TaODORANT1, TaMYB32, TaMYB33, TaMYB64, TaMYB73, TaMYB86B, TaMYBsdu1 and TaMYB19 enhance salt tolerance in transgenic tobacco or Arabidopsis plants [80][81][82][83].…”