Molecular Cloning and Characterization of MbMYB108, a Malus baccata MYB Transcription Factor Gene, with Functions in Tolerance to Cold and Drought Stress in Transgenic Arabidopsis thaliana

Abstract

The MYB transcription factor (TF) family is one of the largest transcription families in plants, which is widely involved in the responses of plants to biotic and abiotic stresses, as well as plant growth, development, and metabolic regulation. In the present study, a new MYB TF gene, <i>MbMYB108</i>, from <i>Malus baccata</i> (L.) Borkh, was identified and characterized. The open reading frame (ORF) of <i>MbMYB108</i> was found to be 903 bp, encoding 300 amino acids. Sequence alignment results and predictions of the protein structure indicated that the MbMYB108 protein contained the conserved MYB domain. Subcellular localization showed that MbMYB108 was localized to the nucleus. The expression of <i>MbMYB108</i> was enriched in young and mature leaves, and was highly affected by cold and drought treatments in <i>M. baccata</i> seedlings. When <i>MbMYB108</i> was introduced into <i>Arabidopsis thaliana</i>, it greatly increased the cold and drought tolerances in the transgenic plant. Increased expression of <i>MbMYB108</i> in transgenic <i>A. thaliana</i> also resulted in higher activities of peroxidase (POD) and catalase (CAT), higher contents of proline and chlorophyll, while malondialdehyde (MDA) content and relative conductivity were lower, especially in response to cold and drought stresses. Therefore, these results suggest that <i>MbMYB108</i> probably plays an important role in the response to cold and drought stresses in <i>A. thaliana</i> by enhancing the scavenging capability for reactive oxygen species (ROS).