Updated project metadata. Lipid remodeling is crucial for plant responses to abiotic stress and metabolic disturbances. A key aspect of this process involves the modification of phosphatidylcholine (PC) acyl chains by lysophosphatidylcholine: acyl-CoA acyltransferases (LPCATs). To understand their role in lipid homeostasis, we studied the trigalactosyldiacylglycerol1 (tgd1) mutant, which exhibits significant increases in fatty acid synthesis and flux through PC due to disrupted inter-organelle lipid trafficking. We discovered that the elevated fatty acid synthesis in tgd1 is due to the posttranslational activation of plastidic acetyl-coenzyme A carboxylase (ACCase). Global transcriptomic profiling revealed 62 significantly upregulated genes in tgd1, with 27 (44%) involved in RNA and DNA modifications, suggesting a role for posttranscriptional mechanisms in adapting to lipid trafficking disruptions. Additionally, transcript levels of LPCATs and several genes regulating ACCase were moderately increased in tgd1. Genetic analysis showed that knocking out LPCAT1 and LPCAT2 was lethal in the tgd1 background. Furthermore, plants homozygous for lpcat2 and heterozygous for lpcat1 in the tgd1 background displayed reduced levels of PC and TAG, along with altered fatty acid compositions. Our findings provide mechanistic insights into fatty acid synthesis regulation and highlight the critical role of LPCATs in maintaining cellular lipid homeostasis when fatty acid production exceeds the cellular demand for membrane lipid synthesis.