There are two principal modes of neurulation: 

1. Primary neurulation

2. Secondary neurulation

TLS Online TPP Program

#Id: 9815

#Unit 6. System Physiology – Plant

The PRD domain of phyB serve as an NLS. 

Conversion of Pr to Pfr by red light expose the functional NLS of the PRD domain of phyB, facilitating phyB’s import into the nucleus.

TLS Online TPP Program

#Id: 9816

#Unit 6. System Physiology – Plant

PRD domain of phyA cannot act as an NLS, so to transport it into the nucleus requires FARRED ELONGATED HYPOCOTYL1 (FHY1) and its homolog FHY1-LIKE (FHL),

TLS Online TPP Program

#Id: 9817

#Unit 6. System Physiology – Plant

Phytochrome responses fall into three major categories based on the amount of light they require: very low fluence responses (VLFRs), low-fluence responses (LFRs), and high-irradiance responses (HIRs).

TLS Online TPP Program

#Id: 9818

#Unit 6. System Physiology – Plant

VLFRs are non-photoreversible.

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.