Nm. Tsvetkova et al., STRUCTURAL CHARACTERISTICS OF THYLAKOID MEMBRANES OF ARABIDOPSIS MUTANTS DEFICIENT IN LIPID FATTY-ACID DESATURATION, Biochimica et biophysica acta. Biomembranes, 1192(2), 1994, pp. 263-271
The ultrastructure of thylakoid membranes from Arabidopsis thaliana wi
ld-type, JB67 and LK3 fatty acid desaturation deficient mutants was st
udied by thin-section and freeze-fracture electron microscopy. There w
as a decrease in the amount of the appressed and non-appressed membran
es in JB67 and LK3 Arabidopsis mutants when compared to the wild type,
resulting in a reduction in the length of photosynthetic membrane per
plastid. The results from freeze-fracture showed a decrease in size a
nd a marked increase in packing density of membrane-associated particl
es on the exo- and endoplasmic fracture faces of the mutants. In addit
ion, areas of the appressed membranes of the mutants contained particl
es in regular arrays under conditions where no such arrays were observ
ed in wild-type thylakoid membranes. These observations suggest, that
the decreased level of lipid fatty acid unsaturation affects the abili
ty of the lipid matrix to mediate the assembly of chloroplast membrane
components. The role of polyunsaturated membrane lipids is considered
in terms of their ability to promote functional oligomeric assemblies
of components of the photosynthetic apparatus.