AUTHOR=Udawat Pushpika , Jha Rajesh K. , Sinha Dinkar , Mishra Avinash , Jha Bhavanath 

TITLE=Overexpression of a Cytosolic Abiotic Stress Responsive Universal Stress Protein (SbUSP) Mitigates Salt and Osmotic Stress in Transgenic Tobacco Plants

JOURNAL=Frontiers in Plant Science

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2016.00518

DOI=10.3389/fpls.2016.00518

ISSN=1664-462X

ABSTRACT=<p>The universal stress protein (USP) is a ubiquitous protein and plays an indispensable role in plant abiotic stress tolerance. The genome of <italic>Salicornia brachiata</italic> contains two homologs of intron less <italic>SbUSP</italic> gene which encodes for salt and osmotic responsive USP. <italic>In vivo</italic> localization reveals that <italic>Sb</italic>USP is a membrane bound cytosolic protein. The role of the gene was functionally validated by developing transgenic tobacco and compared with control [wild-type (WT) and vector control (VC)] plants under different abiotic stress condition. Transgenic lines (T<sub>1</sub>) exhibited higher chlorophyll, relative water, proline, total sugar, reducing sugar, free amino acids, polyphenol contents, osmotic potential, membrane stability, and lower electrolyte leakage and lipid peroxidation (malondialdehyde content) under stress treatments than control (WT and VC) plants. Lower accumulation of H<sub>2</sub>O<sub>2</sub> and <inline-formula><mml:math id="M4" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msubsup><mml:mrow><mml:mi mathcolor="black" mathsize="12pt" mathvariant="normal">O</mml:mi></mml:mrow><mml:mrow><mml:mn mathcolor="black" mathsize="11pt" mathvariant="normal">2</mml:mn></mml:mrow><mml:mrow><mml:mo mathcolor="black" mathsize="11pt" mathvariant="normal">−</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:math></inline-formula> radicals was also detected in transgenic lines compared to control plants under stress conditions. Present study confers that overexpression of the <italic>SbUSP</italic> gene enhances plant growth, alleviates ROS buildup, maintains ion homeostasis and improves the physiological status of the plant under salt and osmotic stresses. Principal component analysis exhibited a statistical distinction of plant response to salinity stress, and a significant response was observed for transgenic lines under stress, which provides stress endurance to the plant. A possible signaling role is proposed that some downstream genes may get activated by abiotic stress responsive cytosolic <italic>Sb</italic>USP, which leads to the protection of cell from oxidative damages. The study unveils that ectopic expression of the gene mitigates salt or osmotic stress by scavenging ROS and modulating the physiological process of the plant.</p>