Functional screening of cDNA library from a salt tolerant
rice genotype Pokkali identiﬁes mannose-1-phosphate guanyl
transferase gene (OsMPG1) as a key member of salinity
Khirod Kumar Sahoo
Sudhir Kumar Sopory
Sneh Lata Singla-Pareek
Received: 9 September 2011 / Accepted: 13 May 2012 / Published online: 29 May 2012
Ó Springer Science+Business Media B.V. 2012
Abstract Salinity, one of the most deleterious stresses,
affects growth and overall yield of crop plants. To identify
new ‘‘candidate genes’’ having potential role in salinity tol-
erance, we have carried out ‘functional screening’ of a cDNA
library (made from a salt tolerant rice—Pokkali). Based on
this screening, we identiﬁed a cDNA clone that was allowing
yeast cells to grow in the presence of 1.2 M NaCl.
Sequencing and BLAST search identiﬁed it as mannose-1-
phosphate guanyl transferase (OsMPG1) gene from rice.
Analysis of rice genome sequence database indicated the
presence of 3 additional genes for MPG. Out of four, three
MPG genes viz. OsMPG1, 3 and 4 were able to functionally
complement yeast MPG mutant -YDL055C. We have car-
ried out detailed transcript proﬁling of all members of MPG
family by qRT-PCR using two contrasting rice genotypes
(IR64 and Pokkali) under different abiotic stresses (salinity,
drought, oxidative stress, heat stress, cold or UV light).
These MPG genes showed differential expression under
various abiotic stresses with two genes (OsMPG1 and 3)
showing high induction in response to multiple stresses.
Analysis of rice microarray data indicated higher expression
levels for OsMPG1 in speciﬁc tissues such as roots, leaves,
shoot apical meristem and different stages of panicle and
seed development, thereby indicating its developmental
regulation. Functional validation of OsMPG1 carried out by
overexpression in the transgenic tobacco revealed its
involvement in enhancing salinity stress tolerance.
Keywords Abiotic stress Á cDNA library Á Mannose-1-
phosphate guanyl transferase Á Microarray Á qRT-PCR Á
Salinity stress results in reduction of crop yield throughout
the world (Boyer 1982; Owens 2001; Munns 2002; Flowers
2004; Cuartero et al. 2006). It is estimated that if current
scenario of salinity stress would persist, we may loose up to
50 % of present cultivated land for agriculture by 2050
(Wang et al. 2003). To improve the yield and tolerance of
plants under adverse environmental conditions, it is
essential to understand the fundamental mechanisms
behind stress tolerance in plants. During the last decade, a
number of genes conferring salt stress tolerance in plants
have been isolated. These genes include those involved in
signal transduction and transcription regulation (Kasuga
et al. 1999; Piao et al. 2001; Chinnusamy et al. 2006; Seki
et al. 2003; Kumari et al. 2009a, b) or those acting as ion
transporters (Apse et al. 1999; Shi et al. 2003; Brini et al.
2007; Verma et al. 2007; Singh et al. 2008; Uddin et al.
2008), or those participating in metabolic pathways (Sa-
kamoto et al. 1998; Singla-Pareek et al.
Screening of microorganisms like Escherichia coli and
yeast, which can efﬁciently express heterologous cDNA
Ritesh Kumar and Ananda Mustaﬁz contributed equally to this paper.
Electronic supplementary material The online version of this
article (doi:10.1007/s11103-012-9928-8) contains supplementary
material, which is available to authorized users.
R. Kumar Á A. Mustaﬁz Á K. K. Sahoo Á V. Sharma Á
S. Samanta Á S. K. Sopory Á S. L. Singla-Pareek (&)
Plant Molecular Biology, International Centre for Genetic
Engineering and Biotechnology, Aruna Asaf Ali Marg,
New Delhi 110067, India
Stress Physiology and Molecular Biology Laboratory,
School of Life Sciences, Jawaharlal Nehru University,
New Delhi 110067, India
Plant Mol Biol (2012) 79:555–568