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

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B. Rathinasabapathi and R. Kaur
3.1.7. Polyamines
In rice and wheat, it has been found that polyamine accumulation affects drought and
salinity tolerance of the plant. Transgenic plants engineered with a chimeric gene for
Datura arginine decarboxylase showed increase in polyamine levels and ultimately,
displayed 5-fold salt tolerance as compared to wild-type plants, and were capable of
surviving and performing well for 20 d without water, whereas wild-type plants started
deterioration if water was withheld for more than 4 d (Capell et. al., 2002; Capell, 2004).
Figure 4. In the members of the Plumbaginaceae, beta-alanine is shared
between the synthesis of osmoprotectant beta-alanine betaine and pantothenate.
NMT is a trifunctional beta-alanine N-methyltransferase (Raman and
Rathinasabapathi, 2003) and PS is pantothenate synthetase (Genschel et. al.,
1999), both presumably cytosolic enzymes
3.1.8. Ectoine
Ectoine is an osmoprotectant found in Halomonas elongata and other halophilic bacteria.
Aspartate semialdehyde is the precursor of ectoine (Ono et. al., 1999). Nakayama
et. al., (2000) engineered tobacco with the three H. elongata genes (ectA, ectB, and
ectC) encoding the enzymes responsible for ectoine synthesis. Transgenic cells were
characterized by the production of low levels of ectoine (