Function of the wheat TaSIP gene in enhancing drought and salt
tolerance in transgenic Arabidopsis and rice
Received: 5 July 2012 / Accepted: 14 January 2013 / Published online: 12 February 2013
Ó Springer Science+Business Media Dordrecht 2013
Abstract Microarray analysis of a salt-tolerant wheat
mutant identiﬁed a gene of unknown function that was
induced by exposure to high levels of salt and subsequently
denoted TaSIP (Triticum aestivum salt-induced protein).
Quantitative PCR analysis revealed that TaSIP expression
was induced not only by salt, but also by drought, abscisic
acid (ABA), and other environmental stress factors.
Transgenic rice plants that expressed an RNA interference
construct speciﬁc for a rice gene homologous to TaSIP was
more susceptible to salt stress than wild-type rice plants.
Subcellular localization studies showed that the TaSIP
localized to the cell membrane. Under conditions of salt
and drought stress, transgenic Arabidopsis plants that
overexpressed TaSIP showed superior physiological prop-
erties compared with control plants, including lower Na
content and upregulation of several stress resistance genes.
Staining of transgenic tissues with b-glucuronidase (GUS)
failed to indicate tissue-speciﬁc activity of the full-length
TaSIP promoter. Quantitative analysis of GUS ﬂuores-
cence in transgenic plants treated with ABA or salt stress
revealed that the region 1,176–1,410 bp from the start
codon contained an ABA-responsive element and that the
region 579–1,176 bp from the start codon upstream of the
exon contained a salt-stress-responsive element. Based on
these results, we conclude that the key part of the TaSIP
gene is the region of its promoter involved in salt tolerance.
Keywords Triticum aestivum Á Quantitative PCR Á
ABA stress Á RNAi Á GUS staining
Soil salinization poses a major challenge to modern agri-
culture. Salt stress affects many plant features, including
yield, protein synthesis, photosynthesis, and energy
metabolism (Parida and Das 2005). Exposure to high
salinity conditions results in low intracellular osmotic
pressure, which causes an imbalance of ions and disrupts
the dynamic ion balance between the cell interior and the
apoplastic space. The resultant ion toxicity greatly inhibits
plant growth and development. The plant growth cycle,
from seed germination and seedling growth to vegetative
and reproductive growth, is thus suppressed under condi-
tions of salt stress (Sairam and Tyagi 2004).
Salt tolerance enables plants to complete their life cycle
in an environment with a high concentration of soluble salt.
Studies on the biology of salt stress have been performed
for over 20 years (Flowers et al. 1977; Greenway and
Munns 1980; Hasegawa et al. 2000; Zhu 2002), but despite
such extensive research effects and the accumulation of
substantial knowledge on plant responses to salt stress, the
functions of many stress-inducible genes remain unknown.
This lack of information underscores the urgent need to
discover more genes that confer salt tolerance and to better
understand both salt tolerance mechanisms and the physi-
ological function of proteins involved in salt tolerance.
Wheat is a major staple crop. Improvements in the tol-
erance of wheat cultivars to environmental stress could
increase yields and provide a secure food source to those
living on land that is marginally cultivable. Due to its
hexaploid genomic structure and large genome, genetic
Electronic supplementary material The online version of this
article (doi:10.1007/s11103-013-0011-x) contains supplementary
material, which is available to authorized users.
H.-Y. Du Á Y.-Z. Shen Á Z.-J. Huang (&)
College of Life Science, Hebei Normal University, Shijiazhuang
050016, People’s Republic of China
Plant Mol Biol (2013) 81:417–429