Gene pyramiding and omics approaches for stress tolerance in leguminous plants - Legumes Under Environmental Stress: Yield, Improvement and Adaptations - page 271

genotypes. One hundred and nine, 210 and 386 genes
showed two-fold changes at the transcriptional level in
these tissues, respectively, of which 2, 15 and 30 genes
were differentially expressed in genotypes sensitive or
tolerant to drought, low temperature and salinity ,
respectively (Mantri et al., 2007). Another important
technique used for sequencing of different cDNAs is
differential display reverse transcriptase PCR (DDRT-
PCR) - used in chickpea plants under water deficit
conditions (Medini et al., 2009).
Many reports also suggest use of the DDRT-PCR
approach for transgenic peanut plants. Overexpression
of the DREB1A gene was observed in pea plants under
abiotic stress. Such reports suggest that transgenic
plants can increase their tolerance to water deficit
stress based on expression of the DREB1A gene (cold-
responsive gene) isolated from Arabidopsis . About 51
differentially expressed transcripts were identified in
peanut plants under abiotic stress conditions, of which
35 were newly expressed, 11 had increased expression
and five had a decrease in their expression (Bhatnagar-
Mathur et al., 2007).
In recent years, six cDNA libraries have been devel-
oped from pea seeds at three different reproductive
stages from tolerant and susceptible genotypes (Guo
et al., 2008). About 700 genes have been derived from
subtractive cDNA libraries of pea plants under water
stress. These studies suggest the importance of HSP70
genes and the role of certain regulators in legume plants
under water deficit stress (Luo et al., 2005). EST libraries
have also been constructed in case of pea plant; for
example, line C34-24 is derived from leaves that pro-
vide resistance to tomato spot wilt, and line A3 from its
pods provides tolerance to drought as well as different
doses of aflatoxin (Proite et al., 2007).

(Gygi et al., 1999). The trilogical approach of transcrip-
tomics, proteomics and metabolomics is intensively used
to study networks at the molecular level in various crop
plants showing tolerance and acclimatization to environ-
mental stresses (Sha et al., 2007; Nanjo et al., 2011)
(Table 16.1).
Proteomics studies of various organelles and subcel-
lular fractions are among the most informative approaches
to understand the function of plant cells. However,
proteomics studies of cell organelles have two major lim-
itations: the need for a stringent purification technique
and purity verification (Alberts et al., 2002). A number of
experimental approaches exist for the identification of
protein-protein interactions and their profiling; these
include yeast two-hybrid analysis and certain computa-
tional methods (Marcotte et al., 1999; Salwinski &
Eisenbergy, 2003; Parrish et al., 2006). Proteomic analysis
is performed using a number of techniques including
mass spectrometry, 2D gel electrophoresis, 2D fluores-
cence difference gel electrophoresis (2D-FDGE) - which
involves the separation of proteins on the basis of
their isoelectric point - and mud PIT (multidimensional
protein identification technology), which involves whole-
cell lysis followed by purification of the proteins
(Subramanian & Smith, 2013).
The metabolism of soybean cells is adversely affected
by several abiotic stresses, which ultimately lead to
deterioration in growth, productivity and proteome
development. As a consequence, it leads to degradation
of proteins, which ultimately leads to degradation of
various phenolic compounds, metabolites, carbohy-
drates and lipids also present therein (Nouri et al., 2011).
A mathematical gene interaction model was prepared
for analysis of protein-protein interactions under flood-
ing stress conditions in soybean seedlings, and it was
observed there was a change in the protein interaction
patterns (Hashiguchi et al., 2009).
A number of stress-induced proteins such as
enzymes involved in osmolyte production are pro-
duced in response to various abiotic stresses in pea
plants. (Matamoros et al., 2003). About 205 protein
spots were differentially expressed in pea plants
adapted to water deficit stress. Profiling was done
using mass spectrometry, which revealed the involve-
ment of several functional and regulatory proteins
(Pandey et al., 2008).
Using nodule proteomics analysis, several stress-
responsive proteins that maintain and regulate root

16.2.2.2 Proteomics
Proteomic analysis is a powerful approach for linking
gene expression to a cell's metabolism (Nouri et al., 2011).
A complete study of the proteins expressed in a cell or
tissue at a specific time (i.e., the proteome) is one of the
most important requisites for understanding biological
functions at the cellular as well as the whole-organism
level. Transcriptomic analysis may not always relate to
protein-protein interaction, protein accumulation and
metabolism under stress conditions therefore a pro-
teomics approach is very important for determining
mechanisms of stress-responsive acclimatization in plants