Salt stress and leguminous crops: Present status and prospects - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 43

expressed phosphorylated PR10 proteins in mediating
salinity stress responses.
Chattopadhyay et al. (2011) have developed
differential proteomes to understand the molecular
basis of salt stress in Lathyrus sativus by subjecting it to
high salinity and other abiotic stresses. About 400 pro-
tein spots were detected in each of the stress proteomes
with one-fourth showing more than a two-fold
difference in expression values. Eighty such proteins
were subjected to liquid chromatography (LC)-tandem
MS/MS analyses, which resulted in the identification of
48 stress-responsive proteins (SRPs) presumably
involved in a variety of functions including metabolism,
signal transduction, protein biogenesis and degradation
and cell defence in a stress-specific manner. The study
provided insights into understanding the range of stress-
regulated proteins and the biological processes they
control as well as having consequences for strategies to
advance stress adaptation in plants.
Protein expression levels were evaluated using a pro-
teomics approach in hypocotyls and roots of soybean
plants subjected to salt stress. In response to salt stress
321 proteins were detected. Seven were reproducibly
found to be upregulated or downregulated. Late
embryogenesis abundant protein, beta conglycinin, elic-
itor peptide three precursor and basic/helix-loop-helix
protein were upregulated, while protease inhibitor, lec-
tin and stem 31-kDa glycoprotein precursor were
downregulated. The study revealed that salt stress can
alter the expression level of certain proteins in the
hypocotyl and root of soybean, and that these may play
a role in the adaptation to salt stress (Aghaei et al.,
2009). Sobhanian et al. (2010b) analysed the proteome
of soybean leaves, hypocotyls and roots under salt
stress. Nineteen, 22 and 14 proteins out of 340, 330 and
235 proteins in the leaves, hypocotyls and roots, respec-
tively, were upregulated or downregulated by NaCl
treatment. Glyceraldehyde-3-phosphate dehydrogenase
was downregulated in the leaf/hypocotyls and fructoki-
nase 2 was downregulated in the hypocotyls/root with
NaCl treatment.
Xu et al. (2011) studied the responses of soybean seeds
of two cultivars, Lee68 and N2800, to salt stress during
germination at both physiological and proteomic levels.
Proteomic approaches identified 350 protein spots, of
which 18 spots showed changes in abundance as a
result of salt stress in both cultivars. Ferritin and
20S

Glyceraldehyde-3-phosphate dehydrogenase, glutathione
S-transferase (GST) 9, GST 10 and seed maturation pro-
tein PM 36 were all downregulated by salt stress in
Lee68. These proteins were upregulated in N2800 under
salt stress. The study indicates the role played by the pro-
teins in defence against salt stress during soybean seed
germination. Ma et al. (2012) investigated the compara-
tive proteomic analysis of soybean seedling leaves of the
salt-sensitive genotype Jackson and the salt-tolerant
genotype Lee68. About 800 proteins were detected and
91 were found to be differentially expressed. The identi-
fied proteins were involved in 14 metabolic pathways
and cellular processes such as ROS production and scav-
enging, accelerated proteolysis and reduced biosynthesis
of proteins, impaired photosynthesis, abundant energy
supply and enhanced biosynthesis of ethylene.
The effect of salt stress on the mitochondrial pro-
teome of lupin ( L. luteus Mister) embryo axes was
investigated by Wojtyla et al. (2013). Twenty-one spots
showed significant alterations in protein expression pro-
files. The identified proteins were associated with
enzymes of the Krebs cycle, mitochondrial electron
transport chain, and enzymes and proteins involved in
mitochondrial biogenesis and stress responses.
The term metabolomics has been described as the
identification and quantitation of all low-molecular-
weight metabolites in a given organism, at a given
developmental stage and in a given organ, tissue or cell
type. This is an interesting task due to the broad array of
molecules with different structures and chemical prop-
erties. Unlike transcriptomics, there is no single approach
to identify all compounds, and the strategic combination
of extraction and identification techniques is key to
enhancing the coverage of the technique. The most
prevalent metabolomics techniques place emphasis on
metabolites with comparable and specific chemical
properties; globally known as metabolite profiling, these
cover only a fraction of the metabolome. To achieve
complete coverage of the wide range of metabolites pre-
sent in the plant kingdom numerous analytical
techniques consisting of a separation technique coupled
to a detection device (usually MS) are shared. However,
there are substitutes that dispense with a separation
technique; such is the case of flow injection analysis
coupled to MS (FIA/MS) or the application of different
analyzers such as nuclear magnetic resonance (NMR) or
Fourier transform infrared spectroscopy (FTIR), which are
utilized only for fingerprinting purposes. The separation proteasome subunit β-6 were upregulated.