Endogenous CK levels (pmol g−1 fresh weight) in leaves and roots of T1 PHT::ZmCKX1 barley plants.

The CKs analyzed included: free bases of trans-zeatin (tZ), cis-zeatin (cZ), dihydrozeatin (DHZ) and N6-isopentenyladenine (iP); their N9-ribosides (tZR, cZR, DHZR, iPR); O-glucosides (tZOG, cZOG, DHZOG); O-glucoside-N9-ribosides (tZROG, cZROG, DHZROG); N9-glucosides (tZ9G, cZ9G, DHZ9G, iP9G); and N9-riboside-5′-monophosphates (tZR5′MP, cZR5′MP, DHZ5′MP, iPR5′MP); sums of free bases and N9-ribosides are considered to comprise the pool of active CKs; mean values with standard deviations obtained from three biological replicates are presented; asterisks indicate significant differences between control and transformed tissue according to Student's unpaired t-tests at P≤0.05; UDL – under detection limit; WT – plants germinated from wild-type grains.