Specific and unspecific responses of plants to cold and drought stress |
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Authors: | Erwin H Beck Sebastian Fettig Claudia Knake Katja Hartig Tribikram Bhattarai |
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Institution: | (1) Department of Plant Physiology, University of Bayreuth, D 95440 Bayreuth, Germany;(2) Botany Department, Amrit Campus, Tribhuvan University, PO Box 102, Kathmandu, Nepal |
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Abstract: | Different environmental stresses to a plant may result in similar responses at the cellular and molecular level. This is due
to the fact that the impacts of the stressors trigger similar strains and downstream signal transduction chains. A good example
for an unspecific response is the reaction to stressors which induce water deficiency e.g. drought, salinity and cold, especially
frost. The stabilizing effect of liquid water on the membrane bilayer can be supported by compatible solutes and special proteins.
At the metabolic level, osmotic adjustment by synthesis of low-molecular osmolytes (carbohydrates, betains, proline) can counteract
cellular dehydration and turgor loss. Taking the example of Pinus sylvestris, changes at the level of membrane composition, and concomitantly of photosynthetic capacity during frost hardening is shown.
Additionally the effect of photoperiod as measured via the phytochrome system and the effect of subfreezing temperatures on
the incidence of frost hardening is discussed. Extremely hydrophilic proteins such as dehydrins are common products protecting
not only the biomembranes in ripening seeds (late embryogenesis abundant proteins) but accumulate also in the shoots and roots
during cold adaptation, especially in drought tolerant plants. Dehydrins are characterized by conserved amino acid motifs,
called the K-, Y-or S-segments. Accumulation of dehydrins can be induced not only by drought, but also by cold, salinity,
treatment with abscisic acid and methyl jasmonate. Positive effects of the overexpression of a wild chickpea (Cicer pinnatifidum) dehydrin in tobacco plants on the dehydration tolerance is shown. The presentation discusses the perception of cold and
drought, the subsequent signal transduction and expression of genes and their products. Differences and similarities between
the plant responses to both stressors are also discussed. |
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Keywords: | Adaptation Arabidopsis molecular response to stress stressors cold forst drought tobacco |
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