Photomorphogenetic Mutants of Higher Plants*

Adamse, P.; Kendrick, Richard E.; Koornneef, M.

doi:10.1111/j.1751-1097.1988.tb02898.x

Cited by 63 publications

(38 citation statements)

References 74 publications

(50 reference statements)

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“…It is thus apparent that, on a per gram fresh weight basis, the mutant produces less photoconvertible PChl(ide) in the dark than does the wild type. Light-labile phytochrome is reduced at least 20-fold in the au mutant (2,17), while PChl was reduced only four-to sixfold (Figs. 1 and 4).…”

Section: Resultsmentioning

confidence: 99%

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Altered Phytochrome Regulation of Greening in an aurea Mutant of Tomato

Ken-Dror

Horwitz²

1990

Plant Physiol.

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A brief pulse of red light accelerates chlorophyll accumulation upon subsequent transfer of dark-grown tomato (Lycopersicon esculentum) seedlings to continuous white light. Such potentiation of greening was compared in wild type and an aurea mutant W616. This mutant has been the subject of recent studies of phytochrome phototransduction; its dark-grown seedlings are deficient in phytochrome, and light-grown plants have yellowgreen leaves. The rate of greening was slower in the mutant, but the extent (relative to the dark control) of potentiation by the red pulse was similar to that in the wild type. In the wild type, the fluence-response curve for potentiation of greening indicates substantial components in the VLF (very low fluence) and LF (low fluence) ranges. Far-red light could only partially reverse the effect of red. In the aurea mutant, only red light in the LF range was effective, and the effect of red was completely reversed by far-red light.

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Section: Resultsmentioning

confidence: 99%

“…Photoresponse mutants in several higher plants are being studied with the aim of elucidating the mechanism of action of phytochrome, cryptochrome, and other photoreceptors in photomorphogenesis (2). Mutations could affect either the photoreceptor(s) or the transduction chain linking the photoevents to a measurable and relevant response.…”

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confidence: 99%

Altered Phytochrome Regulation of Greening in an aurea Mutant of Tomato

Ken-Dror

Horwitz²

1990

Plant Physiol.

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“…As typical dicotyledonous plants, Arabidopsis seedlings are capable of two distinct developmental strategies, skotomorphogenesis in darkness and photomorphogenesis in the light (Mohr and Shropshire, 1983;Kendrick and Kronenberg, 1986;Adamse et al, 1988). The most striking differences between dark-grown and light-grown seedlings are the morphologies of hypocotyls and cotyledons.…”

Section: Introductionmentioning

confidence: 99%

A New Class of Arabidopsis Constitutive Photomorphogenic Genes Involved in Regulating Cotyledon Development.

1993

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Light signals have profound effects on morphogenesis of hypocotyls and cotyledons of Arabidopsis seedlings, but the mechanisms by which light signals are transduced and integrated to control these processes are poorly understood.We report here the identification of a new class of constitutive photomorphogenic (cop) mutants, cop2, cop3, and cop4, in which dark-grown seedlings have open and enlarged cotyledons resembling those of light-grown wild-type seedlings. The epistatic relationships of these three mutations to previously characterized phytochrome-deficient mutations suggest that C O R , COP3, and COP4 may act downstream of phytochrome in the light regulatory pathway. Mutations in each of the three loci.alleviate the normal inhibition of cell-type differentiation, cell enlargement, and lateral cell division obsenred in cotyledons of dark-grown wild-type seedlings, but do not affect plastid differentiation. The cop4 mutation also leads to high-leve1 dark expression of nuclear, but not plastid-encoded, light-inducible genes. We further show that for the nuclear cabl gene encoding a chlorophyll alb binding protein of the photosynthetic light-harvesting complex, activation in dark-grown cop4 mutants is achieved by modulation of promoter activity. Interestingly, COP4 modulates cabl promoter activity through a pathway distinct from that of COPl and COP9. Furthermore, cop4 mutants are detecrive in both root and shoot gravitropic responses, indicating that the COP4 locus may be involved in both light-signaling and gravity-sensing processes.

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“…Genetic analysis of Arabidopsis seedling development has led to the identification of many light regulatory loci, mutations which result in two general classes of contrasting phenotypes (Adamse et al, 1988;Chory, 1993;Deng, 1994). One class comprised hy (long hypocotyl) and blu (blue light-uninhibited hypocotyl elongation) mutants that exhibit reduced responses to light inhibition of hypocotyl elongation.…”

Section: Introductionmentioning

confidence: 99%

Regulatory hierarchy of photomorphogenic loci: allele-specific and light-dependent interaction between the HY5 and COP1 loci.

1994

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Previous studies suggested that the CONSTlTUTlVE PHOTOMORPHOGENIC 7 (COPI) gene product represses photomorphogenic development in darkness and that light signals reverse this action. In this report, we used genetic analysis to investigate the regulatory hierarchical relationship of COPl and the loci encoding the photoreceptors and other signaling components. Our results showed that copl mutations are epistatic to the long hypocotyl mutations hy7, hy2, hy3, and hy4, suggesting that COPl acts downstream of the phytochromes and a blue light receptor. Although epistasis of a putative null cop7-5 mutation over a hy5 mutation implied that COP7 acts downstream of HY5, the same hy5 mutation can suppress the dark photomorphogenic phenotypes (including hypocotyl elongation and cotyledon cellular differentiation) of the weak cop7-6 mutation. This, and other allele-specific interactions between COP 7 and HY5, may suggest direct physical contact of their gene products. In addition, the synthetic lethality of the weak deetiolatedl (detn and Cop7 mutations and the fact that the copl-6 mutation is epistatic to the det7-7 mutation with respect to light control of seed germination and dark-adaptative gene expression suggested that DETT and COP7 may act in the same pathway, with COP7 being downstream. These results, together with previous epistasis studies, support models in which light signals, once perceived by different photoreceptors, converge downstream and act through a common cascade(s) of regulatory steps, as defined by DETT, HY5, COP7, and likely others, to derepress photomorphogenic development.

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Photomorphogenetic Mutants of Higher Plants*

Cited by 63 publications

References 74 publications

Altered Phytochrome Regulation of Greening in an aurea Mutant of Tomato

Altered Phytochrome Regulation of Greening in an aurea Mutant of Tomato

A New Class of Arabidopsis Constitutive Photomorphogenic Genes Involved in Regulating Cotyledon Development.

Regulatory hierarchy of photomorphogenic loci: allele-specific and light-dependent interaction between the HY5 and COP1 loci.

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