Comprehensive Analysis of MYB Gene Family and Their Expressions Under Abiotic Stresses and Hormone Treatments in Tamarix hispida

Abstract

The MYB transcription factors (TFs) is a plant TF families, which involves in hormone signal transduction, and abiotic stress tolerance, etc. However, there are few studies on the MYB TFs family and its regulatory mechanism in <i>Tamarix hispida</i>. In this study, 14 <i>MYB</i> genes (named <i>ThMYB1 - ThMYB14</i>) were cloned and characterized from <i>T. hispida</i>. The transcription profiles of <i>ThMYBs</i> in <i>T. hispida</i> under different abiotic stress conditions were monitored using qRT-PCR. Most of studied <i>ThMYBs</i> were significantly downregulated and/or upregulated by salt and osmotic stress, ABA, GA3 and JA treatments in at least one organ. Especially, <i>ThMYB13</i> was induced in the leaves and roots of <i>T. hispida</i> when exposed to NaCl treatment at all study periods, indicating that it may involve in salt stress. To further study <i>ThMYB1</i>3 function, <i>ThMYB1</i>3 overexpression and knock-down plants and control plants transformed with an empty pROKII were obtained using a transient transformation system. Overexpression of <i>ThMYB1</i>3 in <i>T. hispida</i> displayed the lowest O^2-, H₂O₂ and MDA accumulation, minimal cell death, the most stable K⁺/Na⁺ ratio and the lowest electrolyte leakage rate among the three kinds of transient expression in <i>T. hispida</i>. Conversely, the RNAi-silencing, transiently transformed plants displayed the opposite physiological changes. Therefore, <i>ThMYB1</i>3 might play a role in salt stress tolerance in transgenic <i>T. hispida</i> plants.