Changes in Fatty Acid Composition and Lipid Content Occurring in Potato Leaves during Cold Hardening: the Role of ∆12-Acyl-Lipid Desaturase

Abstract

The qualitative composition and changes in the total fatty acid (FA) content in leaves of wild-type potato (Solanum tuberosum L., cv. Desnitsa) plants and plants transformed with the desA gene of Δ12-acyl-lipid desaturase from Synechocystis sp. PCC 6803 have been studied under cold hardening conditions (6 days at 5°С). During cold adaptation, plants of both types increase their cold resistance, but transformed plants significantly exceed control ones in relation to this parameter. Following cold hardening, the content of total etherified FA in leaves of control plants increases by almost 25% due to the decrease in the content of saturated FA and almost 30% increase in the content of polyunsaturated FA (PUFA); the growth of the PUFA content is provided mainly by linoleic (C18:2) and linolenic (C18:3) acids. Nonhardened leaves of transformed plants are characterized by the same FA content (especially C18:3) as the leaves of hardened control plants. Due to this fact, increase in the total FA content in hardened transformants is not so significant as in the control; at the same time, the content of linoleic (C18:2) acid increases by 30% (the calculated activity index for ∆12-desaturases also slightly increased). The growth of a hexadecatrienic (С16:3) acid content in transformed plants probably results from a low-temperature activation of potato ω3-desaturases. The obtained data allow one to suppose that the higher resistance of transformed plants compared to control ones is connected with a constitutively increased PUFA content and determines more efficient cold hardening of such plants.