EFFECTS OF ABSCISIC-ACID TREATMENT ON THE THERMOSTABILITY OF THE PHOTOSYNTHETIC APPARATUS IN BARLEY CHLOROPLASTS

被引:30
作者
IVANOV, AG
KITCHEVA, MI
CHRISTOV, AM
POPOVA, LP
机构
[1] BULGARIAN ACAD SCI,INST PLANT PHYSIOL,ACAD G BONCHEV ST,BLDG 21,BU-1113 SOFIA,BULGARIA
[2] BULGARIAN ACAD SCI,CENT LAB BIOPHYS,BU-1113 SOFIA,BULGARIA
关键词
D O I
10.1104/pp.98.4.1228
中图分类号
Q94 [植物学];
学科分类号
071001 ;
摘要
Thermostability of the photosynthetic apparatus of abscisic acid (ABA)-treated seedlings of barley (Hordeum vulgare) was studied by light-scattering and by fluorescence measurements of isolated chloroplasts. ABA treatment markedly decreased heat damage of the chloroplast ultrastructure; an exogenous ABA concentration of 10(-5) molar was most effective. Heat-induced increase of the 77 kilodalton fluorescence ratio F740/F685 was also smaller at this ABA concentration. The heat-induced increase of the initial chlorophyll fluorescence level (F(o)) was virtually eliminated in ABA-treated (10(-5) molar) chloroplasts up to 45-degrees-C and slightly increased at 50-degrees-C, relative to control chloroplasts where F(o) increased even at 35-degrees-C and reached its maximal value at 45-degrees-C. In control chloroplasts, F(o) increased with a 5-minute pretreatment temperature, an effect observed as low as 35-degrees-C. F(o) was maximal at 45-degrees-C. In contrast, chloroplasts treated with 10(-5) molar ABA did not exhibit a heat-induced increase in F(o) until 50-degrees-C.
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页码:1228 / 1232
页数:5
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