phytochrome

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phytochrome

pigment

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July 1, 2026

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Phytochrome is a group of proteins found in plants that are bound to light-absorbing pigments. These proteins play a crucial role in initiating floral and developmental processes when activated by red or near-infrared radiation.1

Phytochrome exists in two forms, each absorbing different wavelengths of light. The absorption of red light converts one form to another, which then absorbs far-red light. This conversion process has significant effects on plant growth, including inhibiting stem elongation and stimulating leaf expansion and spore germination. The cycles of red and far-red light can also influence flower formation. This light-sensitive system is a key mechanism in how plants respond to their environment and regulate their development.234

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botany
Historical background
The discovery of the pigment phytochrome, which constitutes a previously unknown light-detecting system in plants, has greatly increased knowledge of the influence of both internal and external environment on the germination of seeds and the time of flowering.
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The discovery of the pigment phytochrome, which constitutes a previously unknown light-detecting system in plants, has greatly increased knowledge of the influence of both internal and external environment on the germination of seeds and the time of flowering.
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coloration
Bilins
Another example is phytochrome, a bilichrome pigment of blue colour, which, although present in very minute quantities in green plants, is indispensable in various photoperiodic processes.
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Another example is phytochrome, a bilichrome pigment of blue colour, which, although present in very minute quantities in green plants, is indispensable in various photoperiodic processes.
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growth
Light
…amounts of a pigment called phytochrome that can exist in two forms. One form absorbs red light (660 millimicrons, or mμ; 1 mμ = 3.937 × 10⁻⁸ inch). When plants containing this pigment absorb red light, the pigment is converted to another form, which absorbs far-red light (730 mμ); the…
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…amounts of a pigment called phytochrome that can exist in two forms. One form absorbs red light (660 millimicrons, or mμ; 1 mμ = 3.937 × 10⁻⁸ inch). When plants containing this pigment absorb red light, the pigment is converted to another form, which absorbs far-red light (730 mμ); the…
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plant development
The emergence of the seedling
…in which the light-sensitive pigment phytochrome plays a part. In most seedlings, the shoot shows a strong attraction to light, or a positive phototropism, which is most evident when the source of light is from one direction. Combined with the response to gravity, this positive phototropism maximizes the likelihood that…
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…in which the light-sensitive pigment phytochrome plays a part. In most seedlings, the shoot shows a strong attraction to light, or a positive phototropism, which is most evident when the source of light is from one direction. Combined with the response to gravity, this positive phototropism maximizes the likelihood that…
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