Cytokinins are phytohormones well known to function in delaying leaf senescence, yet an investigation of different cytokinin isoforms and their temporal regulation of this process remain largely unexamined. Here we studied physiological, transcriptomic, and proteomic effects of the four major natural cytokinin bases trans-zeatin (tZ), isopentenyl adenine (iP), and dihydrozeatin (DZ), cis-Zeatin (cZ)) and their N-conjugated (N7 and N9) forms across four time points: 2, 48, 96, and 144 hours during dark-induced senescence in Arabidopsis leaves.