Cvikrová M., Gemperlová L., Dobrá J., Martincová O., Prášil I., Gubiš J.
PLANT SCIENCE
182:
49-58,
2012
Klíčová slova:
heat stress, polyamines, proline, tobacco
Abstrakt:
The effect of heat stress on the accumulation of proline and on the level of polyamines (PAs)
in tobacco plants was investigated. Responses to heat stress were compared in the upper and lower
leaves and roots of tobacco plants that constitutively over-express a modified gene for the proline
biosynthetic enzyme Δ1-pyrroline-5-carboxylate synthetase (P5CSF129A) and in the corresponding
wild-type. In the initial phases of heat stress (after 2 hours at 40 °C), the accumulation of proline
increased in the wild type but decreased in the transformants. The response to heat stress in prolineover-
producing tobacco plants involved a transient increase in the levels of free and conjugated
putrescine (Put) and in the levels of free spermidine (Spd), norspermidine (N-Spd) and spermine
(Spm) after a 2-h lag phase, which correlated with stimulation of the activity of the corresponding
biosynthetic enzymes. Diamine oxidase (DAO) activity increased in both plant genotypes, most
significantly in the leaves of WT plants. Polyamine oxidase (PAO) activity increased in the roots of WT
plants and decreased in the leaves and roots of the transformants. After 6 h of heat stress, proline
accumulation was observed in the transformants, especially in the lower leaves; much more modest
increase was observed in the WT plants. A decrease in the levels of free and conjugated Put coincided
with down-regulation of the activity of ornithine decarboxylase and marked stimulation of DAO
activity in the leaves and roots of the transformants. PAO activity increased in the roots of the
transformants but decreased in the leaves. Conversely, in WT tobacco subjected to 6 h of heat stress,
slight increases in free and conjugated PA levels were observed and the activity of DAO only increased
in the roots; PAO activity did not change from the value observed during the initial phase of heat stress.
6 hours' heat stress had no effect on the level of malondialdehyde (MDA; a product of lipid
peroxidation), in the upper leaves of either genotype. After a recovery period (2 h at 25 °C), most of the
studied parameters exhibited values comparable to those observed in untreated plants. The
coordination of the proline and polyamine biosynthetic pathways during heat stress conditions is
discussed.
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Autoři z ÚEB: Milena Cvikrová,
Lenka Gemperlová
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