Altered glutathione pool in response to short-term high light stress: Is there any interspecific difference in extremophilic lichens?
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| Year of publication | 2012 |
| Type | Conference abstract |
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| Description | Glutathione is a natural tripeptide with several functions in the plants. Among them, the ability to protect plant cells against various abiotic and biotic stresses is of most importance. In our laboratory, glutathione and its response to high light stress has been studied for a several years. It is generally known that short-term exposure to high light stress decreases glutathione pool (GSH) and increases oxidized form (GSSG). In this study, we focused on glutathione redox state in extremophilic lichen species (e.g. Usnea antartica, Usnea -2 -1 aurantiaco-atra, Pseudocyphellaria endochrysa) exposed to 800 mol.m .s (HL, high light). Glutathione was extracted in HCl and determined by labeling by thiol-binding fluorescence pigment monobromobimane in samples taken before light treatment and after the -2 -1 exposure lasting 10, 20, 30, 40, 50, 60 min., and during dark (11 mol.m .s ) recovery. HPLC evaluation of glutathione redox state was made on HPLC (Waters, USA). In spite of several interspecific differences, there was a general response of gluathione pool to short-term high light stress. After first 10 min. of exposure to HL, GSH increased by 40% due to light- dependent synthesis of glutathione. Further HL exposure led to a gradual decrease with maximum at the end of HL treatment (85% of untreated control). Within this period, the rate of degradation of glutathione was faster than its resythesis. After the HL treatment, i.e. during dark recovery, GSH increased gradually to maximum. In all lichen species, HL treatment led to a change in redox state of glutathione. HL treatment caused an increase in oxidized-to-total glutathione ratio (GSH/GSSG) throughout the whole period of thalli exposition to HL. After the treatment, GSH/GSSG decreased rapidly indicating high capacity of lichens to cope with short-term high light stress. There were species-specific differences in the sensitivity of Usnea antartica, U. aurantiaco-atra, and Pseudocyphellaria endochrysa, their glutathione pool responses to HL in particular. The results support the idea of resistance of Antarctic lichens to high light. |
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