A Transcription Factor SlNAC10 Gene of Suaeda liaotungensis Regulates Proline Synthesis and Enhances Salt and Drought Tolerance

Abstract

The NAC (NAM, ATAF1/2, and CUC2) transcription factors are one of the largest families of transcription factors in plants and play an important role in plant development and the response to adversity. In this study, we cloned a new NAC gene, <i>SlNAC10</i>, from the halophyte <i>Suaeda liaotungensis</i> K. The gene has a total length of 1584 bp including a complete ORF of 1107 bp that encodes 369 amino acids. The <i>Sl</i>NAC10-GFP fusion protein is located in the nucleus and <i>Sl</i>NAC10 has a transcription activation structural domain at the C-terminus. We studied the expression characteristics of <i>SlNAC10</i> and found that it was highest in the leaves of <i>S. liaotungensis</i> and induced by drought, salt, cold, and abscisic acid (ABA). To analyze the function of <i>SlNAC10</i> in plants, we obtained <i>SlNAC10</i> transgenic <i>Arabidopsis</i>. The growth characteristics and physiological indicators of transgenic <i>Arabidopsis</i> were measured under salt and drought stress. The transgenic <i>Arabidopsis</i> showed obvious advantages in the root length and survival rate; chlorophyll fluorescence levels; and the antioxidant enzyme superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities, and the proline content was higher than that of the wild-type (WT) <i>Arabidopsis</i>, whereas the relative electrolyte leakage and malondialdehyde (MDA) content were lower than those of the wild-type <i>Arabidopsis</i>. We explored the regulatory role of <i>Sl</i>NAC10 on proline synthesis-related enzyme genes and found that <i>Sl</i>NAC10 binds to the AtP5CS1, AtP5CS2, and AtP5CR promoters and regulates their downstream gene transcription. To sum up, <i>Sl</i>NAC10 as a transcription factor improves salt and drought tolerance in plants possibly by regulating proline synthesis.