Abstract
Phosphatidic acid (PA) functions as a cell membrane component and signaling molecule in plants. PA metabolism has multiple routes, in one of which PA is converted into cytidine diphosphate diacylglycerol (CDP-DAG) by CDP-DAG synthases (CDSs). CDS genes are highly conserved in plants. Here, we found that knock-down of the CDS gene enhanced the resistance of Arabidopsis thaliana to multiple pathogens, with a growth penalty. When Arabidopsis leaves were treated with chitin or flg22, reactive oxygen species (ROS) production in cds mutants was significantly higher than that in the wild-type (WT). Similarly, phosphorylation of mitogen-activated protein kinases (MAPKs) in the cds1cds2 double mutant was significantly increased compared to the WT. By integrating lipidomics, transcriptomics, and metabolomics data, PA accumulation was observed in mutants cds1cds2, activating the jasmonic acid (JA) and salicylic acid (SA) signaling pathway, and increasing transcript levels of plant defense-related genes. Significant accumulation of the downstream metabolites including serotonin and 5-methoxyindole was also found, which plays important roles in plant immunity. In conclusion, our study indicated the role of CDSs in broad-spectrum disease resistance in Arabidopsis and that CDSs are involved in plant metabolic regulation.