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

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 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 -overexpressing, knockout and wild-type lines of through their whole lifecycle. overexpression prolonged Arabidopsis lifespan in comparison to wild-type plants, whereas knocking out accelerated the plant's senescence. After subjecting the 3-week old seedlings of the studied lines (grown ) 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 1-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 1-overexpressing lines, which green rosettes additionally weighed 4 times more than wild-type. Our results indicate that plants depleted of are more susceptible to cold exposure, while 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 assays of acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) and acylCoA:lysophosphatidylethanolamine acyltransferase (LPEAT) activity in microsomal fractions from the -overexpressing Arabidopsis lines in standard conditions. The results show significant increase in LPEAT and LPCAT activity in comparison to wild-type plants. -overexpressing lines' rosettes also present twice as high expression of in comparison to control. The presented study shows how much heightened expression of augments plant condition after stress and extends its lifespan.