Abstract
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 Tamarix hispida has remained largely unclear. In this study, five SOS genes (ThSOS1–ThSOS5) from T. hispida were cloned and characterized. The expression levels of most ThSOS genes significantly changed after NaCl, PEG6000, and abscisic acid (ABA) treatment in at least one organ. Notably, the expression of ThSOS3 was significantly downregulated after 6 h under salt stress. To further analyze ThSOS3 function, ThSOS3 overexpression and RNAi-mediated silencing were performed using a transient transformation system. Compared with controls, ThSOS3-overexpressing transgenic T. hispida plants exhibited greater reactive oxygen species (ROS)-scavenging capability and antioxidant enzyme activity, lower malondialdehyde (MDA) and H2O2 levels, and lower electrolyte leakage rates under salt stress. Similar results were obtained for physiological parameters in transgenic Arabidopsis, including H2O2 and MDA accumulation, superoxide dismutase (SOD) and peroxidase (POD) activity, and electrolyte leakage. In addition, transgenic Arabidopsis plants overexpressing ThSOS3 displayed increased root growth and fresh weight gain under salt stress. Together, these data suggest that overexpression of ThSOS3 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 ThSOS3 might play an important physiological role in salt tolerance in transgenic T. hispida plants. This study provides a foundation for further elucidation of salt tolerance mechanisms involving ThSOSs in T. hispida.
Highlights
High salinity is a major adverse environmental factor affecting plant growth and development due to osmotic and ionic stress (El Mahi et al, 2019; Yang et al, 2019)
Large variations were found in the theoretical pI values and the molecular weight (MW) values of the proteins encoded by the five ThSOS genes
The results revealed that ThSOS1, ThSOS2, and ThSOS3 genes were closely related to Forward and reverse primers (5 –3 )
Summary
High salinity is a major adverse environmental factor affecting plant growth and development due to osmotic and ionic stress (El Mahi et al, 2019; Yang et al, 2019). ThSOS3 Conferences Salt Stress Tolerance response to such stimuli, and these changes are sensed and decoded by Ca2+ sensors, including calmodulins, calmodulinlike proteins, calcineurin B-like proteins (CBLs), and Ca2+dependent protein kinases (Kudla et al, 2010). The salt overly sensitive (SOS) 3 gene acts as a Ca2+ receptor in plants and is involved in Ca2+ signal-mediated stress responses. This gene, which encodes a calcineurin-like protein, belongs to the CBL gene family and is known as CBL4. Myristylation is important for recruitment of SOS3 to the plasma membrane and for salt tolerance in plants (Quintero et al, 2002). In addition to interacting with SOS3 at the plasma membrane, SOS2 has been reported to interact with and thereby regulate the activity of several tonoplast-localized transporters, such as the Ca2+/H+ antiporter, vacuolar V-ATPase, and the Na+/H+ exchanger (Cheng et al, 2004; Batelli et al, 2007; Huertas et al, 2012)
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