Life Without Phytochromes?
What would happen if you deprived a plant of most of its ability to sense the environmental information provided by light?
That’s the question scientists were attempting to answer by genetically removing all the genes coding for the plant photoreceptor phytochrome.
In a recent report (see Ref. 1 below), Barbara Strasser and colleagues at the Universidad de Buenos Aires, Argentina, found that photosynthesis alone was certainly not enough for plant development, at least for the plant Arabidopsis thaliana.
“Plants use light as a source of energy for photosynthesis and as a source of information about their surrounding environment. Phytochromes, cryptochromes, phototropins, and the zeitlupe family of photoreceptors capture the signals of the environment that provide spatial and temporal information and control growth and development. Phytochromes have absorbance maxima in the red (660 nm) and far-red light (730 nm). They are synthesized as Pr (the inactive form) that is converted by red light to the active form, Pfr. This reaction is reversible by far-red light, which converts Pfr back to Pr. Five phytochrome apoprotein genes are present in the reference plant Arabidopsis thaliana (PHYA–PHYE), each with partially overlapping functions.” (from Ref. 1 below)
Briefly, through the remarkable achievement of a quintuple phytochrome mutant these researchers produced plants devoid of phytochromes. The resulting plants stalled at several critical stages in their development.
Bottom line: The authors conclude: “This demonstrates that photomorphogenic signals are so deeply linked to the processes that control plant development that in the absence of these signals the developmental progress becomes arrested or severely impaired.”
1. Strasser, B., M. Sánchez-Lamasa, M. J. Yanovsky, J. J. Casal, and P. D. Cerdán. (2010) “Arabidopsis thaliana life without phytochromes” Proceedings National Academy Sciences (USA) vol. 107, pp. 4776-4781.
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