Cytokinin Primary site of synthesis -- root tips. High concentrations -- immature seeds and developing fruits

TLS Online TPP Program

#Id: 9859

#Unit 6. System Physiology – Plant

Phototropin contains two light-sensing LIGHT-OXYGEN-VOLTAGE (LOV) domains, LOV1 and LOV2, each binding a chromophore flavin mononucleotide (FMN).

TLS Online TPP Program

#Id: 9860

#Unit 6. System Physiology – Plant

In the dark, the maximum absorption of the FMN chromophore is around 450 nm. 

Blue light induces the formation of a covalent bond between FMN and a cysteine residue, shifting the absorption maximum to 390 nm via a LOV660 intermediate form. The reaction is reversible in darkness.

TLS Online TPP Program

#Id: 9861

#Unit 6. System Physiology – Plant

LOV2 domain is essential for blue light–induced kinase activation and autophosphorylation of the phototropin photoreceptor.

TLS Online TPP Program

#Id: 9862

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 9863

#Unit 6. System Physiology – Plant

TLS Online TPP Program

#Id: 9864

#Unit 6. System Physiology – Plant

Phot2 plays a key role in the avoidance response, and that both phot1 and phot2 contribute to the accumulation response.