Environmental Engineering Reference
In-Depth Information
Since under our conditions the doubling time of the cells is 10-12 h, it is quite likely that
recovery of phycobilisome function requires the development of new cells, via cell
division. Comparison of PSII and phycobilisomes provides an interesting example for a
highly UV-sensitive, but well repaired component in contrast to a low sensitivity, but
inefficiently repaired component.
6. Concluding remarks
Our results clearly demonstrate that PSII is a highly UV-sensitive component of the
photosynthetic apparatus. However, due to its very efficient repair system, PSII damage
becomes limiting for gross photosynthesis only when the repair capacity of the cells is
slowed down by other environmental factors, such as low temperatures, high intensity
visible light, drought, etc. Therefore, in plants exposed to UV-B radiation under additional
environmental stress conditions, which retard the repair of PSII, inhibited electron flow
from PSII can be limiting for the production of ATP and NADPH required for the Calvin
cycle, and consequently for the overall photosynthetic process.
Acknowledgement.
This work was supported by grants from the Hungarian Granting
Agency OTKA (T 034321, T 030592)
References
1. Smith, R.C., Prézelin, B.B., Baker, K.S., Bidigare, R.R., Bouche,r N.P., Coley, T., Karentz, D., MacIntyre,
S., Matlick, H.A., Menzies, D., Ondrusek, M., Wan, Z. and Waters, K J. (1995) Ozone depletion:
Ultraviolet radiation and phytoplankton biology in antarctic waters.
Science
, 255
:
952-959.
2. Jones, L.W. and Kok, B. (1966) Photoinhibition of chloroplast reactions. I. Kinetics and action spectra,
Plant Physiol.
, 41
:
1037-1043.
3. Bornman, J.F. (1989) Target sites of UV-B radiation in photosynthesis of higher plants.
J. Photochem.
Photobiol. B:Biol.
, 4
:
145-158.
4. Vass, I. (1996) Adverse effects of UV-B light on the structure and function of the photosynthetic apparatus
In
Handbook of Photosynthesis
(M. Pessarakli, ed.), Marcel Dekker Inc., New York, pp. 931-950.
5. Strid, A., Chow, W.S. and Anderson, J.M. (1990) Effects of supplementary ultraviolet-B radiation on
photosynthesis in
Pisum Sativum
,
Biochim. Biophys. Acta
, 1020
:
260-268.
6. Basiouny, F.M., Van, T.K. and Biggs, R.H. (1978) Some morphological and biochemical characteristics of
C3 and C4 plants irradiated with UV-B,
Physiol. Plantarum
, 42
:
29-32.
7. Fiscus, E.L. and Booker, F.L. (1995) Is increased UV-B a threat to crop photosynthesis and productivity?,
Photosynth. Res.
, 43: 81-92.
8. Lao, K. and Glazer, A.N. (1996) Ultraviolet-B photodestruction of a light-harvesting complex,
Proc. Natl.
Acad. Sci. USA
, 93: 5258-5263.
9. Renger, G., Völker, M., Eckert, H.J., Fromme, R., Hohm-Veit, S. and Graber, P. (1989) On the mechanism
of photosystem II deterioration by UV-B irradiation,
Photochem. Photobiol.
, 49: 97-105.
10.Vass, I., Sass, L., Spetea, C., Bakou, A., Ghanotakis, D. and Petrouleas, V. (1996) UV-B induced
inhibition of photosystem II electron transport studied by EPR and chlorophyll fluorescence. Impairment
of donor and acceptor side components,
Biochemistry
, 35: 8964-8973.
11. Post, A., Lukins, P.B., Walker, P.J. and Larkum, A.W.D. (1996) The effects of ultraviolet irradiation on
P680
+
reduction in PS II core complexes measured for individual S-states and during repetitive cycling of
the oxygen-evolving complex,
Photosynth. Res
,
.
49: 21-27.
12. Strid, A., Chow, W.S. and Anderson, J.M. (1994) UV-B damage and protection at the molecular level in
plants,
Photosynth. Res.
, 39: 475-489.
13. Nogués, S. and Baker, N.R. (1995) Evaluation of the role of damage to photosystem II in the inhibition of
CO
2
assimilation in pea leaves on exposure to UV- B radiation,
Plant Cell Environ.
, 18: 781-787.
14. Andersson, B. and Styring, S. (1991) Photosystem II: Molecular organization, function, and acclimation,
Curr. Top. Bioenerg.
, 16
:
1-81.
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