Extracellular basic hydroxyproline rich glycoproteins

(HRGPs) via the tyrosine in the repeated motif PPPPY that reacts with H2O2.

TLS Online TPP Program

#Id: 10199

#Unit 6. System Physiology – Plant

IPT1, IPT3, IPT5, and IPT8 are located in plastids, and the relative expression levels of IPT3 and IPT5 are higher than the other IPTs

TLS Online TPP Program

#Id: 10200

#Unit 6. System Physiology – Plant

KNOX gene expression increases cytokinin levels in the shoot apical meristem by upregulating the cytokinin biosynthetic gene ISOPENTENYL TRANSFERASE7 (IPT7)

TLS Online TPP Program

#Id: 10201

#Unit 6. System Physiology – Plant

Cytokinin Primary site of synthesis -- root tips.

High concentrations -- immature seeds and developing fruits

TLS Online TPP Program

#Id: 10202

#Unit 6. System Physiology – Plant

Many plant tissues contain the enzyme cytokinin oxidase, which cleaves the side chain from zeatin (both cis and trans), zeatin riboside, iP, and their N-glucosides, but not their O-glucoside derivatives

TLS Online TPP Program

#Id: 10203

#Unit 6. System Physiology – Plant

Biological effects of cytokinins

Removes inhibitory phosphate

Promotes accumulation of G1 cyclins (CycD)

TLS Online TPP Program

#Id: 10204

#Unit 6. System Physiology – Plant

Cytokinin has been linked to the activation of a Cdc25- like phosphatase, whose role is to remove an inhibitory phosphate group from the Cdc2 kinase. 

Cytokinins elevate the expression of the CYCD3 gene, which encodes a D-type cyclin'