Agriculture Reference
In-Depth Information
ascorbate pool has been observed in transformed plants overexpressing GR (Foyer
et al.
1995
).
Nicotiana tabacum
and
Populus
×
Canescens
plants have higher foliar
ascorbate contents and improved tolerance to oxidative stress (Aono et al.
1993
;
Foyer et al.
1995
). Demirevska-Kepova et al. (
2006
) reported that the content of
oxidized ascorbate increased during Cd exposure in
Hordeum vulgare
plants. A
decrease in the ascorbate content in the roots and nodules of
Glycine max
under
Cd stress has been observed (Balestrasse et al.
2001
). Cadmium also decreases
ascorbate content in
Cucumis sativus
chloroplast and in the leaves of
Arabidopsis
thaliana
,
Pisum sativum
and
Brassica campestris
(Zhang et al.
2003
; Skorzynska-
Polit et al.
2003
/04; Romero-Puertas et al.2007; Anjum et al.
2008
), respectively,
whereas it remained unaffected in
Populus
×
Canescens
roots (Schutzendubel et al.
2002
).
5 Conclusion
Literature is full with the reports to counteract the inhibitory effects of Cd in crop
plants but we still need sound information to understand the plant responses to Cd
toxicity at genomic level to know more about the structural and functional altera-
tions under Cd stress in crop plants. Cadmium toxicity in plants is observed at whole
plant as well as at cellular and molecular levels, the important of which include
perturbation of metabolic pathways such as photosynthesis, energy transduction,
protein synthesis and nutritional disorders, etc. Plants adopt various mechanisms
to counteract the inhibitory effects of Cd toxicity by synthesizing metal binding
peptides and/or altering the activity of the components of antioxidant machinery.
Strategies should aim at manipulating steps of antioxidant defense pathways, thiol
production by overexpression of the enzymes of the pathway. Genetic engineering
of PC biosynthesis pathway can also be a target to overcome the Cd toxicity as well
as the signal pathways through which Cd toxicity leads to gene regulation, are also
important to look into.
Acknowledgements
Work on plant abiotic stress tolerance in NT's laboratory is partially sup-
ported by the Department of Science and Technology (DST), Government of India, and Depart-
ment of Biotechnology (DBT), Government of India.
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