A tomato (Lycopersicon esculentum Mill.) zeaxanthin epoxidase gene (LeZE) was isolated and antisense transgenic tomato plants were produced. Northern, southern, and western blot analyses demonstrated that antisense LeZE was transferred into the tomato genome and the expression of LeZE was inhibited. The ratio of (A+Z)/(V+A+Z) in antisense transgenic plants was maintained at a higher level than in the wild type (WT) plants under high light and chilling stress with low irradiance. The value of non-photochemical quenching (NPQ) in WT and transgenic plants was not affected during the stresses. The oxidizable P700 and the maximal photochemical efficiency of PSII (Fv/Fm) in transgenic plants decreased more slowly at chilling temperature under low irradiance. These results suggested that suppression of LeZE caused zeaxanthin accumulation, which was helpful in alleviating photoinhibition of PSI and PSII in tomato plants under chilling stress. and N. Wang ... [et al.].
Cell membranes of the cyanobacterium Phormidium lamino.sum were separated into two fractions by centrifugation in a stepwise sucrose gradient. One fraction contained mature thylakoid membranes and the other one contained membranes morphologically similar to primary membranes of pea etiochloroplasts. The latter ones represented an electron-transparent base with numerous electron-dense inclusions. The predominant type of the inclusions was rod-like structures containing presumably ribosomes.