LOG encodes a novel cytokinin activating enzyme that directly controls meristem activity in rice

Abstract

Cytokinin plays a crucial role for maintenance of shoot meristem function. Cytokinin is first synthesized as a nucleotide form, and then converted to the bioactive free-base form. Although the activating step is important to regulate cytokinin activity, the genetic and biochemical nature has not been identified. We report that the LOG (LONELY GUY) gene, whose mutants confer defects in the maintenance of shoot meristems, encodes a novel cytokinin activating enzyme in rice. LOG has phosphoribohydrolase activity, which directly converts a cytokinin nucleotide to the free-base form with the release of a ribose 5'-monophosphate. Our findings revise the long-held idea of multi-step reactions, cytokinin nucleotide can be directly activated to the free-base form by LOG. We will show you data biochemically and genetically characterizing the LOG and its homologs.