Coaction of Phytochrome and Blue/UV Light Photoreceptors

Mohr, Hans; Drumm‐Herrel, H.; Oelmüller, R.

doi:10.1007/978-3-642-69767-8_2

Cited by 19 publications

(13 citation statements)

References 21 publications

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“…A phytochrome (Pfr) independent involvement of a BL/UV-A photoreceptor in the induction of these photoresponses could have easily been detected in the mutant. This reasoning would argue in favor of the hypothesis that the signal transduction chain originating from a BL/UV-A photoreceptor requires Pfr for its action [7,8,11,12,20,22,23,26,27]. On the other hand, the aurea mutation might cause pleiotropic effects and cause not only a rapid degradation of the phytochrome apoprotein, but affect the BL/UV-A photoreceptor and/or the signal transduction chain originating from it as well.…”

Section: Response Of Transcript Levels For Normally Photoregulated Gementioning

confidence: 84%

“…In higher plants photomorphogenesis is brought about by at least 3 photoreceptor systems: phytochrome, blue (BL)/UV-A light photoreceptor(s) and a UV-B light photoreceptor [20,22,23,26,27]. While phytochrome and its action has been investigated intensively, a BL/UV-A light photoreceptor has not yet been identified, and little is known about its action.…”

Section: Introductionmentioning

confidence: 99%

“…Mohr and co-workers have shown that one function of the BL/UV-A light photoreceptor is to enhance the effectiveness of Pfr [see 22,23,26,27]. Analysis of a variety of photoresponses ranging from light control ofhypocotyl elongation to modulation ofmRNA levels [7-9, 26, 27] has led to the hypothesis that phytochrome controls the terminal response while light absorbed by a BL/UV-A photoreceptor only increases the responsiveness of the system to the far-redabsorbing form of phytochrome, Pfr [22,23]. Analyzing the effect of BL/UV-A and phytochrome (Pfr) on hypocotyl growth inhibition, Gaba and Black argue by contrast that a BL/UV-A photoreceptor evokes the terminal response and requires Pfr to express (or enhance) its activity [13,14].…”

Section: Introductionmentioning

confidence: 99%

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Blue-light mediated accumulation of nuclear-encoded transcripts coding for proteins of the thylakoid membrane is absent in the phytochrome-deficient aurea mutant of tomato

1989

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Polyclonal antibodies against pea phytochrome detect 2 protein bands (about 116 and 120 kDa) on blots of crude protein extracts and protein of microsomal preparations of dark-grown tomato seedlings. Both protein bands are undetectable in Western blots of the aurea mutant extracts. Neither protein band is detectable after isogenic wild-type seedlings are illuminated with 3 h of red light, either in the crude extract or in the membrane fraction of the irradiated seedlings; this result is consistent with the hypothesis that both bands are phytochrome. When dark-grown wild-type seedlings are illuminated with 3 h of red light or blue light against a red light background, the transcript levels for chlorophyll a/b-binding proteins of photosystem I and II, plastocyanin, and the subunit II of photosystem I increase. In all cases, the same fluence rate of blue light is much more effective than red light alone, a result that indicates the involvement of a blue/UV-A light photoreceptor in addition to the involvement of the far-red-absorbing form of phytochrome, Pfr. The aurea mutant responds neither to red light nor to blue light. Thus, no Pfr-independent induction of the four transcripts by a blue/UV-A light photoreceptor can be measured in the aurea mutant.

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Section: Response Of Transcript Levels For Normally Photoregulated Gementioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Blue-light mediated accumulation of nuclear-encoded transcripts coding for proteins of the thylakoid membrane is absent in the phytochrome-deficient aurea mutant of tomato

1989

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“…The most prominent changes are in leaf pigmentation. Light stimulates Chl biosynthesis by stimulating the reduction of Pchlide but, more particularly, by stimulating the synthesis of severa1 early regulatory enzymes of this pathway (Mohr et al, 1984; Rüdiger and Schoch, 1988).Not only Chl but also the carotenoid content is increased during light-dependent transition from etioplasts to chloroplasts. Carotenoids are present in etioplasts but in a lower amount than in the corresponding chloroplasts (Grumbach, 1981; Bany et al, 1991 …”

mentioning

confidence: 99%

mentioning

confidence: 99%

Light-Stimulated Carotenoid Biosynthesis during Transformation of Maize Etioplasts Is Regulated by Increased Activity of Isopentenyl Pyrophosphate Isomerase

Albrecht

Sandmann

1994

Plant Physiol.

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Light-stimulated carotenoid biosynthesis associated with the transformation of etioplasts to chloroplasts was investigated after dark-grown maize (Zea mays) seedlings were transferred into light.These studies focused on the enzymes of the pathway to detect those enzyme activities that were stimulated in the light and thus that were responsible for increased biosynthesis of carotenoids. In preliminary experiments, norflurazon, an inhibitor of phytoene desaturase, was used to prevent phytoene being further metabolized to carotenoids. Light-dependent stimulation of phytoene accumulation indicated that the light-regulated steps are located in the pathway leading to phytoene synthesis. The use of the "Clabeled precursors mevalonic acid, isopentenyl pyrophosphate, and farnesyl pyrophosphate pointed to increased activity of an enzyme involved in the biosynthetic steps between isopentenyl pyrophosphate and farnesyl pyrophosphate. Determination of the adivities of all five enzymes of the pathway involved in the sequence from mevalonic acid to phytoene revealed that the only enzyme activity stimulated by light was isopentenyl pyrophosphate isomerase. Over a 3-h period of illumination, this enzyme activity, like carotenoid biosynthesis, was stimulated 2.8-fold.Light is essential for plant life. It serves not only as an energy source in photosynthesis but also influences plant growth and development. During leaf formation, the maturation of proplastids into chloroplasts requires light. In nonilluminated plants etioplasts are formed instead, which can be recognized by their crystal-like structure (Boardman, 1977); after illumination, however, etioplasts are converted very rapidly into fully functioning chloroplasts. During this photomorphogenic event, massive structural and biochemical modifications occur. The most prominent changes are in leaf pigmentation. Light stimulates Chl biosynthesis by stimulating the reduction of Pchlide but, more particularly, by stimulating the synthesis of severa1 early regulatory enzymes of this pathway (Mohr et al., 1984; Rüdiger and Schoch, 1988).Not only Chl but also the carotenoid content is increased during light-dependent transition from etioplasts to chloroplasts. Carotenoids are present in etioplasts but in a lower amount than in the corresponding chloroplasts (Grumbach, 1981; Bany et al., 1991 529light to chloroplasts, the formation of carotenoids is also stimulated in parallel to the biosynthesis of Chl (Cohen and Goodwin, 1962; Virgin, 1967;Frosch and Mohr, 1980).It is generally assumed that photomorphogenesis and photoinduction of metabolism proceed via light-mediated gene expression, followed by enhanced protein synthesis including increased concentrations of appropriate enzymes leading to enhanced biosynthetic capacities (Hoober, 1987). This model may also apply for photoregulation of carotenogenesis (Tobin and Silverthome, 1985).In the present investigation, work was focused on the last step in this chain of events: the formation of enzymes of the carotenoid biosynthetic pathw...

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Coaction between pigment systems

Mohr

1994

Photomorphogenesis in Plants

114

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Coaction of Phytochrome and Blue/UV Light Photoreceptors

Cited by 19 publications

References 21 publications

Blue-light mediated accumulation of nuclear-encoded transcripts coding for proteins of the thylakoid membrane is absent in the phytochrome-deficient aurea mutant of tomato

Blue-light mediated accumulation of nuclear-encoded transcripts coding for proteins of the thylakoid membrane is absent in the phytochrome-deficient aurea mutant of tomato

Light-Stimulated Carotenoid Biosynthesis during Transformation of Maize Etioplasts Is Regulated by Increased Activity of Isopentenyl Pyrophosphate Isomerase

Coaction between pigment systems

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