AUTHOR=Liu Zhongyuan , Xie Qingjun , Tang Feifei , Wu Jing , Dong Wenfang , Wang Chao , Gao Caiqiu 

TITLE=The ThSOS3 Gene Improves the Salt Tolerance of Transgenic Tamarix hispida and Arabidopsis thaliana

JOURNAL=Frontiers in Plant Science

VOLUME=11

YEAR=2021

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.597480

DOI=10.3389/fpls.2020.597480

ISSN=1664-462X

ABSTRACT=<p>The salt overly sensitive (SOS) signal transduction pathway is one of the most highly studied salt tolerance pathways in plants. However, the molecular mechanism of the salt stress response in <italic>Tamarix hispida</italic> has remained largely unclear. In this study, five <italic>SOS</italic> genes (<italic>ThSOS1</italic>–<italic>ThSOS5</italic>) from <italic>T. hispida</italic> were cloned and characterized. The expression levels of most <italic>ThSOS</italic> genes significantly changed after NaCl, PEG<sub>6000</sub>, and abscisic acid (ABA) treatment in at least one organ. Notably, the expression of <italic>ThSOS3</italic> was significantly downregulated after 6 h under salt stress. To further analyze <italic>ThSOS3</italic> function, <italic>ThSOS3</italic> overexpression and RNAi-mediated silencing were performed using a transient transformation system. Compared with controls, <italic>ThSOS3</italic>-overexpressing transgenic <italic>T. hispida</italic> plants exhibited greater reactive oxygen species (ROS)-scavenging capability and antioxidant enzyme activity, lower malondialdehyde (MDA) and H<sub>2</sub>O<sub>2</sub> levels, and lower electrolyte leakage rates under salt stress. Similar results were obtained for physiological parameters in transgenic Arabidopsis, including H<sub>2</sub>O<sub>2</sub> and MDA accumulation, superoxide dismutase (SOD) and peroxidase (POD) activity, and electrolyte leakage. In addition, transgenic Arabidopsis plants overexpressing <italic>ThSOS3</italic> displayed increased root growth and fresh weight gain under salt stress. Together, these data suggest that overexpression of <italic>ThSOS3</italic> confers salt stress tolerance on plants by enhancing antioxidant enzyme activity, improving ROS-scavenging capability, and decreasing the MDA content and lipid peroxidation of cell membranes. These results suggest that <italic>ThSOS3</italic> might play an important physiological role in salt tolerance in transgenic <italic>T. hispida</italic> plants. This study provides a foundation for further elucidation of salt tolerance mechanisms involving <italic>ThSOS</italic>s in <italic>T. hispida</italic>.</p>