The acidity of oxalic acid induces regulated cell death in Arabidopsis

Abstract

Abstract Key message The acidity of oxalic acid (OA) induces an unknown type of cell death in Arabidopsis. Acid treatment and Sclerotinia sclerotiorum infection trigger some overlapping transcriptomic responses. The influx of calcium is likely required for OA-induced cell death in Arabidopsis. Abstract Numerous pathogens trigger host cell death that either favors or blocks infection. Many phytopathogens produce cytolytic compounds functioning as virulence determinants, like oxalic acid (OA). It was reported that oxalate itself but not the acidity of OA induced programmed cell death in plants. Accumulation of oxalate often reaches millimolar concentrations, and the pH value decreases to around 4.0 in the Sclerotinia sclerotium -infected plant tissues. However, the role of OA acidity in inducing cell death remains unknown. We used the approaches of Sytox green/fluorescein diacetate (FDA)/propidium iodide (PI)/Evan's blue staining, transcriptomic analysis, and dynamic gene expression analysis to investigate the role of OA acidity in inducing cell death and the regulatory mechanisms of OA-induced cell death. We found that the acidity of OA and HCl induced cell death in Arabidopsis with characteristic features including impaired plasma membrane and induction of cell-death related genes, but not DNA fragmentation. Moreover, calcium influx is required for OA-induced cell death. Our work reveals that acids induce an uncharacterized-type of cell death that is a regulated process, instead of a passive event.