Plant purine catabolism─recent advances and the emerging role in stress adaptation

Abstract

Purine catabolism is ubiquitous in organisms, serving for the maintenance of cellular purine homeostasis.　In plants, another important role played by this metabolism is attributed to the recycling of purine-derived ammonia to general nitrogen metabolism for sustainable growth and development.　It has also been suggested that certain purine metabolites and enzymes are involved in plant adaptation to environmental stress.　The recent completion of molecular identification of the enzymes in Arabidopsis has made it possible, by using molecular genetic approaches, to examine the physiological importance of the pathway in these contexts.　Notably, recent forward and reverse genetic studies have revealed the emerging role in stress tolerance, highlighting xanthine dehydrogenase as a modulator of reactive oxygen species homeostasis and the intermediate allantoin as a stress protectant.　This review summarizes up-to-date research progress in plant purine catabolism and associated metabolites, focusing on the current outline of the enzymatic route, transgenic/mutant phenotype characterization, and possible protective mechanisms against abiotic and biotic stress.