AUTHOR=Singh Dinkar , Yadav Narendra Singh , Tiwari Vivekanand , Agarwal Pradeep K. , Jha Bhavanath 

TITLE=A SNARE-Like Superfamily Protein SbSLSP from the Halophyte Salicornia brachiata Confers Salt and Drought Tolerance by Maintaining Membrane Stability, K+/Na+ Ratio, and Antioxidant Machinery

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00737

DOI=10.3389/fpls.2016.00737

ISSN=1664-462X

ABSTRACT=<p>About 1000 salt-responsive ESTs were identified from an extreme halophyte <italic>Salicornia brachiata</italic>. Among these, a novel salt-inducible gene <italic>SbSLSP</italic> (<underline>S</underline><italic>alicornia</italic><underline>b</underline><italic>rachiata</italic><underline>S</underline>NARE-<underline>l</underline>ike <underline>s</underline>uperfamily <underline>p</underline>rotein), showed up-regulation upon salinity and dehydration stress. The presence of <italic>cis</italic>-regulatory motifs related to abiotic stress in the putative promoter region supports our finding that <italic>SbSLSP</italic> gene is inducible by abiotic stress. The SbSLSP protein showed a high sequence identity to hypothetical/uncharacterized proteins from <italic>Beta vulgaris, Spinacia oleracea, Eucalyptus grandis</italic>, and <italic>Prunus persica</italic> and with SNARE-like superfamily proteins from <italic>Zostera marina and Arabidopsis thaliana</italic>. Bioinformatics analysis predicted a clathrin adaptor complex small-chain domain and N-myristoylation site in the SbSLSP protein. Subcellular localization studies indicated that the SbSLSP protein is mainly localized in the plasma membrane. Using transgenic tobacco lines, we establish that overexpression of <italic>SbSLSP</italic> resulted in elevated tolerance to salt and drought stress. The improved tolerance was confirmed by alterations in a range of physiological parameters, including high germination and survival rate, higher leaf chlorophyll contents, and reduced accumulation of Na<sup>+</sup> ion and reactive oxygen species (ROS). Furthermore, overexpressing lines also showed lower water loss, higher cell membrane stability, and increased accumulation of proline and ROS-scavenging enzymes. Overexpression of <italic>SbSLSP</italic> also enhanced the transcript levels of ROS-scavenging and signaling enzyme genes. This study is the first investigation of the function of the <italic>SbSLSP</italic> gene as a novel determinant of salinity/drought tolerance. The results suggest that <italic>SbSLSP</italic> could be a potential candidate to increase salinity and drought tolerance in crop plants for sustainable agriculture in semi-arid saline soil.</p>