ISHS Acta Horticulturae 597: International Conference on Medicinal and Aromatic Plants (Part II)
BETAINES IN THE PLANT KINGDOM AND THEIR USE IN AMELIORATING STRESS CONDITIONS IN PLANTS |
| Author: | G. Blunden |
| Keywords: | betaines, stress conditions, root knot nematodes, [14C] glycinebetaine uptake, gene induction, freezing tolerance, salinity stress |
| Abstract:
Betaines have a widespread distribution in the plant and animal kingdoms. The most studied role of these compounds is that of compatible osmolytes, facilitating adaptation to saline and dry environments. Betaines can be accumulated to levels greater than 5 µmol g–1 dry weight, at which concentration they are likely to function as compatible osmolytes. However, many species contain these compounds in very much lower concentrations and their role in these cases has not been fully elucidated. Recent studies on the application of betaines in low amounts to plants has resulted in significant enhancement of the ability of the treated plants to resist stress conditions. For example, application of glycinebetaine,  -aminobutyric acid betaine and  -aminovaleric acid betaine to dwarf French bean, tomato, wheat and barley plants led to significantly higher leaf chlorophyll levels in the treated plants in comparison to the controls.
Application of the same betaines to tomato plants also resulted in significantly reduced invasion of the roots of the plants by second stage juveniles of the root knot nematodes, Meloidogyne javanica and M. incognita. Egg recovery from the roots of the treated plants was also significantly reduced.
Application of betaines to plants in low concentrations has also led to significantly lower levels of fungal attack.
Application of [14C]-glycinebetaine to leaves of turnip rape plants resulted in the labelled compound being detected in the roots within two hours of application.
Within one day after application, the labelled glycinebetaine had been translocated to all plant parts.
Treatment of wheat plants with glycinebetaine led to a significantly increased tolerance to freezing stress.
The glycinebetaine treatment resulted in the induction of a subset of low temperature responsive genes that are also induced by salinity and drought stresses.
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