PJB-2017-694
ISOLATION AND CHARACTERIZATION OF MBWRKY3, A WRKY TRANSCRIPTION FACTOR GENE FROM MALUS BACCATA (L.) BORKH INVOLVED IN DROUGHT TOLERANCE IN TRANSGENIC TOBACCO
Deguo HAN
Abstract
Plant specific WRKY transcription factors (TFs) are involved in stress responses such as drought, high salinity, heat, or cold as well as abscisic acid (ABA) signaling. However, their roles in abiotic stresses are still not well known in Malus plants. In the present study, a WRKY gene is isolated from Malus baccata (L.) Borkh and designated as MbWRKY3. The MbWRKY3 gene encodes a protein of 352 amino acid residues with a theoretical isoelectric point of 8.53 and a predicted molecular mass of 39.5 kDa. MbWRKY3 protein contains one WRKY domain and one C2H2 zinc-finger motif (C-X5-C-X23-H-X-H). Subcellular localization reveals that MbWRKY3 was preferentially localized in nucleus. The expression levels of MbWRKY3 were up-regulated by salinity, drought, and ABA treatments in M. baccata seedlings. When MbWRKY3 was introduced into tobacco, it improved drought stress tolerance in transgenic plants. When dealt with drought treatment, the transgenic plants had the higher relative water content, and contents of proline and chlorophyll than wild type (WT). Compared to WT, the over-expression of MbWRKY3 in transgenic tobacco also led to decreased levels of elecrolyte leakage (EL), MDA, and H2O2 when dealt with drought stress. Moreover, there were increased activities of the ROS-related enzymes (SOD, CAT, and POD), and greater up-regulations of the corresponding genes (NtSOD, NtCAT, and NtPOD) in transgenic lines, especially when dealt with drought stress. These results suggest that MbWRKY3 gene plays a positive regulatory role in drought stress response.
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