Physiology and Molecular Biology of Stress ... - KHAM PHA MOI

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A.K. Tyagi, S. Vij and N. Saini
expression levels of genes in response to different stresses, which can be used to
characterize mutants. Mutant analysis in turn will give more definite knowledge of each
gene function but even in case of mutant analysis the phenotype is not always evident
and requires complementation studies. Hence, transgenics would be needed before
function can be established or a new functional allele tested. The key point is that no
single technique will help identify gene function but the focus should be on an integrated
approach. The information obtained from gene discovery and expression profiling
should be complemented with a systematic study of tagged mutant collections.
Complementation and over-expression studies will help identify the key players of
stress response and also their inter-relationships (Fig. 2). The genes identified through
such effort would not only reveal gene function but would also identify the particular
combination of genes. Pyramiding of such genes will help develop ‘the model stress
tolerant crop’ which is of course the ultimate aim of these efforts.
EXPRESSION GENOMICS
Sequencing of stress-related ESTs and cDNA
libraries Use of high throughput techniques such
as microarray and SAGE to study expression
MUTANT ANALYSIS
Screening of mutants for altered stress response
Positional and insertion-tag based cloning of
the target stress gene
Computational prediction of gene function
through database searches
(See section on resources for functional genomics)
FUNCTIONAL VALIDATION OF GENE FUNCTION
TRANSGENICS
Confirmation of gene function through over
expression and supression of target genes
PROTEOMICS
Use of MALDI TOF and yeast two hybrid
system to identify and quantify proteins and
study their interactions
Figure 2. A step-by-step functional genomics strategy to study stress tolerance in plants
8. ACKNOWLEDGEMENTS
Our research work is supported by grants from the Department of Biotechnology, Government
of India. SV is recipient of Research Fellowship from CSIR.