The protein phosphatases of abscisic acid coreceptors mediate carbon metabolism in Arabidopsis

Abstract Abscisic acid (ABA) is involved in various processes in plant growth, development and stress responses. Clade A protein phosphatases of type 2C (PP2Cs) inhibit the core kinases of ABA signaling in the absence of ABA and serve as ABA coreceptors by forming a complex with the receptor in the presence of ABA. There are nine clade A PP2Cs in Arabidopsis, and previously, the triple mutants lacking three of the four selected PP2Cs exhibited impaired growth under well-watered conditions, partly because of the enhanced stress-related gene expression by ABA. However, the underlying molecular mechanism remains largely obscure. To gain further insights into molecular events mediated by the PP2Cs, we performed metabolite profiling using gas-chromatography mass-spectrometry in ABA-insensitive and -hypersensitive mutants of the PP2Cs. A comparative analysis revealed that several metabolites, including organic and amino acids, exhibited opposite accumulation patterns in these PP2C mutants. Moreover, candidate enzyme and transporter genes downstream of the PP2Cs were identified by re-analyzing previously reported transcriptome data. Together with independent multi-omics studies, including metabolite profiling, on other ABA core signaling components, these results suggested that ABA signaling was associated with the tricarboxylic acid cycle for adequate production of energy and amino acids.