No abstract

Plants can mitigate environmental stress conditions through acclimation. In the case of fluctuating stress conditions such as high temperatures, maintaining a stress memory enables a more efficient response upon recurring stress. In a genetic screen for Arabidopsis thaliana mutants impaired in the memory of heat stress (HS) we have isolated the FORGETTER2 (FGT2) gene, which encodes a type 2C protein phosphatase (PP2C) of the D-clade. Fgt2 mutants acquire thermotolerance normally; however, they are defective in the memory of HS. FGT2 interacts with phospholipase D a2 (PLDa2), which is involved in the metabolism of membrane phospholipids and is also required for HS memory. In summary, we have uncovered a previously unknown component of HS memory and identified the FGT2 protein phosphatase and PLDa2 as crucial players, suggesting that phosphatidic acid-dependent signaling or membrane composition dynamics underlie HS memory.