Phospholipid:Diacylglycerol Acyltransferase1 Overexpression Delays Senescence and Enhances Post-heat and Cold Exposure Fitness

Abstract

In an alternative pathway to acyl-CoA: diacylglycerol acyltransferase (DGAT)-mediated triacylglycerol (TAG) synthesis from diacylglycerol, phospholipid:diacylglycerol acyltransferase (PDAT) utilizes not acyl-CoA but an acyl group from sn-2 position of a phospholipid, to form TAG. The enzyme’s activity in vitro matches DGAT’s in a number of plant species, however its main function in plants (especially in vegetative tissue) is debatable. In the presented study, we cultivated PDAT1-overexpressing, pdat1 knockout and wild-type lines of Arabidopsis thaliana through their whole lifecycle. PDAT1 overexpression prolonged Arabidopsis lifespan in comparison to wild-type plants, whereas knocking out pdat1 accelerated the plant’s senescence. After subjecting the 3-week old seedlings of the studied lines (grown in vitro) to 2-h heat stress (40°C) and then growing them for one more week in standard conditions, the difference in weight between wild-type and PDAT1-overexpressing lines increased in comparison to the difference between plants grown only in optimal conditions. In another experiment all lines exposed to 2-week cold stress experienced loss of pigment, except for PDAT1-overexpressing lines, which green rosettes additionally weighed 4 times more than wild-type. Our results indicate that plants depleted of PDAT1 are more susceptible to cold exposure, while PDAT1 overexpression grants plants a certain heat and cold resilience. Since it was shown, that lysophospholipids may be intertwined with stress response, we decided to also conduct in vitro assays of acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) and acylCoA:lysophosphatidylethanolamine acyltransferase (LPEAT) activity in microsomal fractions from the PDAT1-overexpressing Arabidopsis lines in standard conditions. The results show significant increase in LPEAT and LPCAT activity in comparison to wild-type plants. PDAT1-overexpressing lines’ rosettes also present twice as high expression of LPCAT2 in comparison to control. The presented study shows how much heightened expression of PDAT1 augments plant condition after stress and extends its lifespan.

Distinct Physiological Roles of Three Phospholipid:Diacylglycerol Acyltransferase Genes in Olive Fruit with Respect to Oil Accumulation and the Response to Abiotic Stress

“…Regarding high temperature, when olive fruit was incubated at 35°C the transcript levels of the three olive PDAT genes remained almost unaffected ( Figure 7B ). Interestingly, it has been recently reported that heat stress stimulates AtPDAT1 expression in rosettes of Arabidopsis seedlings ( Demski et al, 2020 ). Furthermore, AtPDAT1-mediated TAG accumulation in Arabidopsis seedlings has been found to increase heat resistance and augments basal thermotolerance ( Mueller et al, 2017 ).…”

“…Further studies also revealed a critical physiological role for AtPDAT1-mediated TAG synthesis in the protection against fatty acid-induced cell death in growing tissues ( Fan et al, 2013b ), and in the process of diverting fatty acids from membrane lipids toward β-oxidation, thereby maintaining membrane lipid homeostasis in Arabidopsis leaves ( Fan et al, 2014 ). In the same tissue, it has also been reported that AtPDAT1 could be involved in stress responses ( Fan et al, 2017 ; Mueller et al, 2017 ; Demski et al, 2020 ), although the role of PDAT in plant responses to different stresses remains to be completely elucidated.…”

In Vitro Growth Conditions Boost Plant Lipid Remodelling and Influence Their Composition

“…Data on C. sativa are still missing. Our results concerning the fatty acid composition of acyl-lipids in C. sativa leaves show that this plant possesses a similar composition of fatty acids to A. thaliana , both when plants are cultured in in vivo [ 16 , 34 , 35 ] and in in vitro conditions [ 31 ]. The composition of individual lipid classes in leaves from in vivo conditions also seems to be comparable to that of A. thaliana [ 16 ].…”

“…Recently, many studies in the field of lipid biochemistry have also been conducted based on the use of in vitro cultures. Most of them concern the determination of the activity of enzymes related to lipid biosynthesis, mainly focusing on the comparison of wild lines and genetically modified ones or testing the impact of diverse abiotic stresses [28][29][30][31]. These studies often do not take into account the effect of the introduced modifications on plants grown under standard conditions (in vivo), which might be completely different, such as in the case of secondary metabolite production.…”

Transcriptional Regulation of Metabolic and Cellular Processes in Durum Wheat (Triticum turgidum subsp. durum) in the Face of Temperature Increasing

“…High temperatures affect the lipid composition and viscosity of the membrane, the hotter temperature made more fluid cell membranes. This phenomenon is attributed to the activation of the accumulation and remodeling of the lipid composition of the membrane (Figure 4) [35,36].…”