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Salinity has a considerable effect on world agriculture, significantly
reducing productivity of agricultural plants. In response to salinity
stress, a series of genes, such as those encoding for ion channels and
osmolytes, are upregulated to help mitigate damage, March 2005 by Narendra
Tuteja.

Because DNA helicase from pea protects plants from stress induced by high
salt concentrations, Dr. Narendra Tuteja and colleagues surmised that DNA
helicases must also be upregulated in response to high salinity stress1.

DNA helicases are enzymes responsible for unwinding DNA, a necessary step in
gene transcription, and thereby are involved in maintaining genome
integrity. Using a pea plant model, the researchers found that pea DNA
helicase 45 (PDH45) transcript is increased three-fold in response to high
salt concentrations.

The helicase was also upregulated in response to other stresses, such as
dehydration and low temperatures. To examine the function of PDH45, Dr.
Tuteja?s group developed a transgenic tobacco plant containing the gene.
Wild type tobacco plants suffered in response to high salt, but transgenic
plants overexpressing PDH45 protein continued to grow. In addition,
subsequent generations of transgenic tobacco plants maintained the exogenous
gene and continued to resist high salt stress, suggesting that stress
tolerance can be manipulated in crop plants.

Overexpression of DNA and RNA helicases provides a possible example of the
exploitation of DNA/RNA unwinding pathways for engineering salinity
tolerance without affecting yield in crop plants.

[www.isb.vt.edu]

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