Abstract
BACKGROUND: One of the most common abiotic stressors for plants is cold temperature and the principal adaptation of plant cells to this stressor is the remodeling of membranes fluidity. In the present studies we investigated the role of acyl-CoA: lysophatidylethanolamine acyltransferases (LPEAT), one of the enzymes involved in phospholipids re-synthesis and remodeling, in Arabidopsis plants adaptation to cold temperature. RESULT: Arabidopsis control plants and mutants with knockout and overexpression of the AtLPEAT1 and AtLPEAT2 were grown under cold and standard temperatures (4 °C and 21 °C respectively) and their development was monitored. Both overexpressors produced higher biomass of the rosettes than control plants (wild-type; WT) and the rosettes of lpeat2 and lpeat1xlpeat2 mutants were much smaller than WT plants. Unexpectedly, lpeat1 mutant developed bigger rosettes than WT plants. All lpeat mutants showed prolonged senescence of rosettes leaves and delayed start of flowering than WT plants. Contrary to growth under standard temperature, the LPEAT1-OE, lpeat2 and lpeat1 x lpeat2 mutants cultivated under low temperature exhibited yellow-green colour, in contrast to dark green colour of leaves of WT, LPEAT2-OE and lpeat1 mutant. Biochemical analyses of photosynthetic pigments showed greater differences in their content and composition in analysed Arabidopsis lines cultivated under cold temperature than under standard temperature. In all lpeat mutants, decrease in the amount of all analysed lipid classes per unit of fresh weight was detected, however, it was the most pronounced in the case of phosphatidylglycerol (PG) and monogalactosyldiacylglycerol (MGDG). The strong correlation between different expression levels of genes encoding LPEAT enzymes, in the tested plant lines, and the LPEAT and LPGAT activity (lysophoshatidylethanolamine and lysophoshatidylglycerol serve as fatty acid acceptors, respectively) were noted. This type of correlation concerned also remodelling intensity of phosphatidylethanolamine (PE) and PG. CONCLUSIONS: The study has shown that the previously observed effects of overexpression and knockout of LPEAT genes occur independently of cultivation condition, and that the cold temperature modifies these effects and brings new anomalies. They showed also that LPEAT enzymes are important (in some cases indispensable) in the remodelling of PE and PG and in the re-synthesis of PG.