Adaptive Alterations in the Ultrastructure of Chloroplasts and the Contents of Pigments and Sugars under Low Temperature Hardening of Potato Plants: Role of Δ12 Acyl-Lipid Desaturase

Abstract

Alterations in the ultrastructure of chloroplasts and the content of sugars during low-temperature hardening (5°C, 6 days) of potato plants (Solanum tuberosum L., cv. Desnitsa) and a transformed line with the desA gene of Δ12 acyl-lipid desaturase Synechocystis sp. RCC 6803 were studied. It was noted that during hardening, sugars were accumulated in the leaves of both lines, but with greater speed in the leaves of the transformants. In control plants after hardening, an increase in the total number of thylakoid membranes and in the number of plastoglobules per chloroplast were obtained accompanied by a decrease in the chloroplast cross-sectional area and starch grain area. It was found that chloroplasts of transformed plants, which were different from the control plants in the higher absolute content of membrane lipids and the amount of polyunsaturated fatty acids, corresponded to the hardened plants before cold exposure by some ultrastructural parameters. In the early period of low-temperature hardening, the transformed plants were more adaptable, according to the data on the sugar content.