Description:
The plant hormone cytokinin, existing in several molecular forms, is perceived bymembrane-localized histidine kinases. The signal is transduced to transcription factorsof the type-B response regulator family localized in the nucleus by a multi-step histidineaspartatephosphorelay network employing histidine phosphotransmitters as shuttleproteins across the nuclear envelope. The type-B response regulators activate a numberof primary response genes, some of which trigger in turn further signaling events andthe expression of secondary response genes. Most genes activated in both rounds oftranscription were identified with high confidence using different transcriptomic toolkitsand meta analyses of multiple individual published datasets. In this review, we attempt tosummarize the existing knowledge about the primary and secondary cytokinin responsegenes in order to try connecting gene expression with the multitude of effects thatcytokinin exerts within the plant body and throughout the lifespan of a plant.