Phytochrome

Phytochromes are a class of <a href="/facts/Photoreceptor_protein/xEa6hcY7">photoreceptor proteins</a> found in <a href="/facts/Plant/X5BMDMvS">plants</a>, <a href="/facts/Bacteria/wC8xSCsU">bacteria</a> and <a href="/facts/Fungus/BHo5DP59">fungi</a>. They respond to light in the <a href="/facts/Red/gLnFAVx4">red</a> and <a href="/facts/Far-red/MFkx9VSo">far-red</a> regions of the <a href="/facts/Visible_spectrum/frPBh8o5">visible spectrum</a> and can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light. Recent advances have suggested that phytochromes also act as temperature sensors, as warmer temperatures enhance their de-activation. All of these factors contribute to the plant's ability to <a href="/facts/Germination/BdNz4TyV">germinate</a>.
Phytochromes control many aspects of plant development. They regulate the <a href="/facts/Germination/BdNz4TyV">germination</a> of <a href="/facts/Seeds/a4xGSLxJ">seeds</a> (photoblasty), the synthesis of <a href="/facts/Chlorophyll/1Sb0NyyM">chlorophyll</a>, the elongation of seedlings, the size, shape and number and movement of <a href="/facts/Leaf/1m6wCNTg">leaves</a> and the timing of <a href="/facts/Flowering/7gI5Kefw">flowering</a> in adult plants. Phytochromes are widely expressed across many tissues and developmental stages.
Other plant photoreceptors include <a href="/facts/Cryptochrome/YS0gfB1X">cryptochromes</a> and <a href="/facts/Phototropin/5FKjKUlr">phototropins</a>, which respond to <a href="/facts/Blue/DHWb8MUa">blue</a> and <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a>-A light and <a href="/facts/UVR8/uD3zlPUU">UVR8</a>, which is sensitive to <a href="/facts/Ultraviolet/kncBUqn5">ultraviolet</a>-B light.

Phytochrome open-in-new

Phytochrome