Question

_{In a short essay(100-150) words, summarize phytochrome's role in altering shoot growth for the enhancement of light capture?}

Answer 1

Answer:

• Plants need to modify their growth and development through various signals present in the environment.
• The most important signals are the light signal that plays a role from seedling to the reproductive cycle of the plants.
• For this purpose, the higher plants have developed through the course of evolution, three major signal- transducing photoreceptors namely:

The red/far‐red (R/FR) light‐absorbing phytochromes,

The UV‐A/blue light‐absorbing cryptochromes and,

phototropins

• The phytochromes are photochromic biliproteins that have a maximum absorbance in the red (R) and far‐red (FR) regions of the spectrum.
• Phytochromes are usually produced in their inactive form which is R- absorbing (Pr) and later in this inactive form when transduced with signals gets converted to an active form which is FR- absorbing (Pfr).
• The conversion of Pr (maximum absorbance at 666 nm) to Pfr (maximum absorbance at 730 nm) and vice versa is reversible.
• The active form, Pfr initiates the biological activities in the plants.
• Hence, to carry out various biological activities, phytochromes release various signal molecules that allow the plant to grow their shoot length, in order to capture ample amount of light in the range of 666 nm and 730 nm corresponding to Pr and Pfr regions of the spectrum.

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