BaDBL1, a unique DREB gene from desiccation tolerant moss Bryum argenteum, confers osmotic and salt stress tolerances in transgenic Arabidopsis

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.

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Populus euphratica JRL Mediates ABA Response, Ionic and ROS Homeostasis in Arabidopsis under Salt Stress

International Journal of Molecular Sciences ◽

10.3390/ijms20040815 ◽

2019 ◽

Vol 20 (4) ◽

pp. 815

Author(s):

Huilong Zhang ◽

Chen Deng ◽

Jun Yao ◽

Yan-Li Zhang ◽

Yi-Nan Zhang ◽

...

Keyword(s):

Salt Stress ◽

Transgenic Plants ◽

Transgenic Arabidopsis ◽

Populus Euphratica ◽

Nacl Stress ◽

Callus Cultures ◽

Schematic Model ◽

Mesophyll Cells ◽

Ros Homeostasis ◽

Aba Response

Sodium chloride (NaCl) induced expression of a jacalin-related mannose-binding lectin (JRL) gene in leaves, roots, and callus cultures of Populus euphratica (salt-resistant poplar). To explore the mechanism of the PeJRL in salinity tolerance, the full length of PeJRL was cloned from P. euphratica and was transformed into Arabidopsis. PeJRL was localized to the cytoplasm in mesophyll cells. Overexpression of PeJRL in Arabidopsis significantly improved the salt tolerance of transgenic plants, in terms of seed germination, root growth, and electrolyte leakage during seedling establishment. Under NaCl stress, transgenic plants retained K+ and limited the accumulation of Na+. PeJRL-transgenic lines increased Na+ extrusion, which was associated with the upward regulation of SOS1, AHA1, and AHA2 genes encoding plasma membrane Na+/proton (H+) antiporter and H+-pumps. The activated H+-ATPases in PeJRL-overexpressed plants restricted the channel-mediated loss of K+ that was activated by NaCl-induced depolarization. Under salt stress, PeJRL–transgenic Arabidopsis maintained reactive oxygen species (ROS) homeostasis by activating the antioxidant enzymes and reducing the production of O2− through downregulation of NADPH oxidases. Of note, the PeJRL-transgenic Arabidopsis repressed abscisic acid (ABA) biosynthesis, thus reducing the ABA-elicited ROS production and the oxidative damage during the period of salt stress. A schematic model was proposed to show the mediation of PeJRL on ABA response, and ionic and ROS homeostasis under NaCl stress.

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