Overexpression of a Plasma Membrane-Localized SbSRP-Like Protein Enhances Salinity and Osmotic Stress Tolerance in Transgenic Tobacco

Abstract

An obligate halophyte, Salicornia brachiata grows in salt marshes and is considered to be a potential resource of salt- and drought-responsive genes. It is important to develop an understanding of the mechanisms behind enhanced salt tolerance. To increase this understanding, a novel SbSRP gene was cloned, characterized, over-expressed, and functionally validated in the model plant Nicotiana tabacum. The genome of the halophyte S. brachiata contains two homologs of an intronless SbSRP gene of 1,262 bp in length that encodes for a stress-related protein. An in vivo localization study confirmed that SbSRP is localized on the plasma membrane. Transgenic tobacco plants (T1) that constitutively over-express the SbSRP gene showed improved salinity and osmotic stress tolerance. In comparison to Wild Type (WT) and Vector Control (VC) plants, transgenic lines showed elevated relative water and chlorophyll content, lower malondialdehyde content, lower electrolyte leakage and higher accumulation of proline, free amino acids, sugars, polyphenols, and starch under abiotic stress treatments. Furthermore, a lower build-up of H2O2 content and superoxide-radicals was found in transgenic lines compared to WT and VC plants under stress conditions. Transcript expression of Nt-APX (ascorbate peroxidase), Nt-CAT (catalase), Nt-SOD (superoxide dismutase), Nt-DREB (dehydration responsive element binding factor), and Nt-AP2 (apetala2) genes was higher in transgenic lines under stress compared to WT and VC plants. The results suggested that overexpression of membrane-localized SbSRP mitigates salt and osmotic stress in the transgenic tobacco plant. It was hypothesized that SbSRP can be a transporter protein to transmit the environmental stimuli downward through the plasma membrane. However, a detailed study is required to ascertain its exact role in the abiotic stress tolerance mechanism. Overall, SbSRP is a potential candidate to be used for engineering salt and osmotic tolerance in crops.

Chrysanthemum CmHSFA4 gene positively regulates salt stress tolerance in transgenic chrysanthemum

“…Salt stress affects mRNA editing in chloroplasts (Rodrigues et al ., ). This is consistent with the observation in Salicornia brachiata stress‐related protein ( SbSRP ) transgenic tobacco with enhanced tolerance to salt stress (Udawat et al ., ). Leaves of the salinity‐stressed wild‐type chrysanthemum plants were more affected by chlorosis and contained less chlorophyll than the CcSOS1 transgenic plants (Gao et al ., ).…”

Halophytes: Potential Resources for Salt Stress Tolerance Genes and Promoters

“…Among all, Thellungiella halophila is one of the halophytes emerging as a model halophyte for the study of abiotic stress tolerance mechanism (Wang et al, 2004 ; Amtmann, 2009 ). Halophyte Cakile maritima and Suaeda maritima (Megdiche et al, 2009 ; Sahu and Shaw, 2009 ) are considered as model plants for the transcript profiling and Salicornia brachiata as a potential halophyte for new and useful salt-tolerant genes (Singh et al, 2016 ; Udawat et al, 2016 , 2017 ). In this review, halophytes are discussed as resources for salt stress tolerance genes, which can be explored further for developing abiotic stress tolerance crops for sustainable agriculture.…”

“…Most of these genes encode for Na + /H + antiporters (vacuolar or plasma membrane), vacuolar pyrophosphatase, potassium transporters, ion channels, antioxidants, ROS scavengers, and proteins that involve in protective function and signal transduction. Additionally, some novel salt responsive genes were also cloned and characterized from halophytes like S. brachiata (Udawat et al, 2014 , 2017 ; Singh et al, 2016 ).…”

Knockdown of Cytochrome P450 Genes Gh_D07G1197 and Gh_A13G2057 on Chromosomes D07 and A13 Reveals Their Putative Role in Enhancing Drought and Salt Stress Tolerance in Gossypium hirsutum

“…Due to ever-changing environmental conditions and a high rate of pollution, plants have evolved various survival strategies to cope with water deficit and salinity stress [13]. The evolutionary strategy adopted by plants, due to their sessile life, is through physiological and or molecular processes of modulating the concentration levels of the various phytohormones and induction of the stress response genes [14,15]. Among the most important plant secondary metabolites are the brassinosteroids (BR), known to be involved in a series of plant physiological pathways, in addition to plant growth and development [16].…”