Lesson plan
Phytochrome
Phytochromes are a class of photoreceptor proteins found in plants as well as certain fungi and bacteria. Characteristically they use bile pigments to absorb light in the red to far-red region of the spectrum, changing their colour as they do so (see Fig. 1). Phytochromes control many aspects of plant development, inducing seed germination, seedling development (see Fig. 2), shade avoidance and daylength-dependent flowering by regulating the expression of thousands of genes through the action of phytochrome-associated transcription factors. Higher plant genomes encode several phytochromes with significantly different characteristics and functions. Other plant photoreceptors include cryptochromes and phototropins, which respond to blue and near ultraviolet (UV-A) light, and UVR8, which responds to ultraviolet-B light. Phytochromes have been identified in certain fungi and shown to regulate pigmentation and sexual development. Prokaryotic phytochromes regulate very diverse processes including pigment accumulation and fruiting-body assembly. The mechanism by which the phytochrome molecule itself is activated by light and how it then transmits the light signal to the cell are a major research fields in molecular biology. There is also interest in the possibility of exploiting these processes in biotechnology and other areas.
Article summary
Phytochromes are a class of photoreceptor proteins found in plants as well as certain fungi and bacteria. Characteristically they use bile pigments to absorb light in the red to far-red region of the spectrum, changing their colour as they do so (see Fig. 1). Phytochromes control many aspects of plant development, inducing seed germination, seedling development (see Fig. 2), shade avoidance and daylength-dependent flowering by regulating the expression of thousands of genes through the action of phytochrome-associated transcription factors. Higher plant genomes encode several phytochromes with significantly different characteristics and functions. Other plant photoreceptors include cryptochromes and phototropins, which respond to blue and near ultraviolet (UV-A) light, and UVR8, which responds to ultraviolet-B light. Phytochromes have been identified in certain fungi and shown to regulate pigmentation and sexual development. Prokaryotic phytochromes regulate very diverse processes including pigment accumulation and fruiting-body assembly. The mechanism by which the phytochrome molecule itself is activated by light and how it then transmits the light signal to the cell are a major research fields in molecular biology. There is also interest in the possibility of exploiting these processes in biotechnology and other areas.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.