ЭлБиб

NaCUNDUCED CHANGES IN OXYGEN EVOLVING ACTIVITY

ADAPTATION TO SALINITY

. • I ,

N.G.Gambarova

Baku State University, Azerbaijan

Photosynthesis of many piants decreased drastically'as a result ofNaCl salinity

(Dale et all, 1967; Flowers et all, 1977; Greenway and Munns, 1980 Gambarova et all,

J988).

Many plant species, however, are capable of adapting to extreme salinity.

Photosynthetic membranes are stress sensitive sites but little information is available

regarding the structure changes associated with salt stress (Carter and Chessman, 1993).

In this respect the analysis of chloroplast structure and function is an important

part of the study of NaCl salinity effect on the photosynthetic apparatus. In this paper

report that thylakoids isolated from plants subjected to a prolonged exposure .to NaCl

salinity display an increased tolerance towards high concentration ofNaCl after in vitro

incubation. This was evident in a stabilization of an activity of the oxygen evolving

PSII.

In this adaptive process may be to play a specific role protector materials, example

ABA, which promoted some structure reorganization of the chloroplast membranes,

leading to an increase in the number of PSIIa centers and an enhanced participation of

cooperative mechanism for oxygen production.

In the experiments to obtain NaCl stepwise-treated plants, seeds of barley daily

increase in NaCl concentration was 20 mM until 100 mM NaCl was reached after five

days. In vitro treatment of isolated thylakoids was performed in 1 M NaCl solutions for

10 min before measurements. Barley thylakoids were isolated by Gamm 'and Green

(1980). Tlie activity of electron transport from water to p-benzoguinone was measured

polarographically. Thylakoids were equivalent to 20 mmol Chl/ml. The water-oxidizing

system was by DCP1P reduction (30 mM DCP1P). Chloroplasts equivalent to 15

mg/Chl/ml.

The initial oxygen burst (induction* curves) and the oxygen flash yields were

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