Role of Fatty Acid ω3 Acyl-Lipid Desaturases in Low-Temperature Hardening of Solanum tuberosum L.

Abstract

The role of fatty acid ω3 acyl-lipid desaturases in low-temperature hardening (7 days at 3°C) of potato plants (Solanum tuberosum L., cv. Yubilei Zhukova) was studied. It was found that transcriptions of the three genes of ω3 acyl-lipid desaturases present in the potato genome significantly differed in their response to low temperature. The content of the FAD3 gene transcripts dramatically fell in the first day of cooling and was not restored until the end of the hardening period. The FAD7 gene was constitutively expressed through almost the entire adaptation period. The level of the FAD8 gene transcripts sharply increased in the first day of the hardening. The total fraction of trienoic fatty acids, which are synthesized by ω3 acyl-lipid desaturases, rose by 3% during the hardening, which is a relatively large value for potato. The hardened plants, in comparison with the unhardened ones, manifested a higher net photosynthesis/dark respiration ratio, higher (2.5-fold) concentration of soluble sugars, and stronger resistance to negative (–2 or –3°C) temperatures. It is suggested that the augmentation of the trienoic FA fraction, which are mainly localized in the thylakoid membranes of the potato chloroplasts, sustains the photosynthesis under low temperatures. Therefore, the maintenance of photosynthetic activity during the low-temperature acclimation supplies the plant with photoassimilates that are the principal sources of energy and metabolites necessary for the establishment of potato plant resistance to hypothermia.