The authors have investigated the thermally induced structural rearrangements in the lipid phase of the thylacoid membranes of the chloroplasts of cucumber and melon leaves, species of the genus Cucumis differing in thermophilicity. It is shown that the characteristic break in the graph of the temperature dependence of the spectral parameter 2T∥′ of the e.s.r. spectrum of the spin label reflecting the degree of mobility and orientation order of the label in the membrane, occurs at a higher temperature in the chloroplasts of the melon adapted to cultivation in a hotter climate as compared with the cucumber. Together with this it was established that melon chloroplasts possess higher stability of the Hill reaction to heating and lipolytic hydrolysis by phospholipase A2. It is concluded that the melon thylacoid membranes have a more rigid structure than those of the cucumber. The importance of this pattern in the adaptation of the cell functions of the plants to the temperature of the medium is discussed.
|Number of pages||5|
|Publication status||Published - Dec 1 1988|
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