Profilin enhances the exchange of ADP for ATP on G-actin. Cofilin enhances the rate of loss of ADP-actin from the filament (−) end. Thymosin-β4, binds to ATP–G-actin in such a way that it inhibits addition of the actin subunit to either end of the filament.

TLS Online TPP Program

#Id: 9819

#Unit 6. System Physiology – Plant

Arabidopsis seeds can be induced to germinate with red light in the range of 0.001 to 0.1 μmol m–2 at very-low-fluence responses (VLFRs).

TLS Online TPP Program

#Id: 9820

#Unit 6. System Physiology – Plant

LFRs is found at red region (660 nm) and (720 nm) includes processes such as the promotion of lettuce seed germination, inhibition of hypocotyl elongation, and regulation of leaf movements.

TLS Online TPP Program

#Id: 9821

#Unit 6. System Physiology – Plant

A brief pulse of red light will induce a response, provided that the light is sufficiently bright, and conversely, very dim light will work if the irradiation time is long enough. 

This reciprocal relationship between fluence rate and time is known as the law of reciprocity

TLS Online TPP Program

#Id: 9822

#Unit 6. System Physiology – Plant

VLFRs and LFRs both obey the law of reciprocity

TLS Online TPP Program

#Id: 9823

#Unit 6. System Physiology – Plant

HIRs require prolonged or continuous exposure to light of relatively high irradiance, and the response is proportional to the irradiance

TLS Online TPP Program

#Id: 9824

#Unit 6. System Physiology – Plant

Plants that increase stem extension in response to shading are said to exhibit a shade avoidance response.

As shading increases, the R:FR ratio decreases. Shade means far red light