Photomorphogenic Responses of Long Hypocotyl Mutants of Tomato

Koornneef, M.; Cone, J.W.; Dekens, R. G.; O'Herne-Robers, E.G.; Spruit, C. J. P.; Kendrick, Richard E.

doi:10.1016/s0176-1617(85)80019-5

Cited by 133 publications

(96 citation statements)

References 16 publications

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“…Mutations in the chromophore biosynthesis pathway affect all phytochrome species and, as such, have been widely used as phytochromedeficient plants for photomorphogenetic studies, such as hy1 (17) and hy2 (18,19) in Arabidopsis, yg-2 (20) and au (21,22) in tomato, pcd1 (23) and pcd2 (24) in pea, se5 (25) in rice, and so on. Strictly speaking, however, these mutants cannot be equated to phytochrome-deficient mutants.…”

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confidence: 99%

Phytochromes are the sole photoreceptors for perceiving red/far-red light in rice

Takano

Inagaki

Xie

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

125

115

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Phytochromes are believed to be solely responsible for red and far-red light perception, but this has never been definitively tested. To directly address this hypothesis, a phytochrome triple mutant (phyAphyBphyC) was generated in rice (Oryza sativa L. cv. Nipponbare) and its responses to red and far-red light were monitored. Since rice only has three phytochrome genes (PHYA, PHYB and PHYC), this mutant is completely lacking any phytochrome. Rice seedlings grown in the dark develop long coleoptiles while undergoing regular circumnutation. The phytochrome triple mutants also show this characteristic skotomorphogenesis, even under continuous red or far-red light. The morphology of the triple mutant seedlings grown under red or far-red light appears completely the same as etiolated seedlings, and they show no expression of the light-induced genes. This is direct evidence demonstrating that phytochromes are the sole photoreceptors for perceiving red and far-red light, at least during rice seedling establishment. Furthermore, the shape of the triple mutant plants was dramatically altered. Most remarkably, triple mutants extend their internodes even during the vegetative growth stage, which is a time during which wild-type rice plants never elongate their internodes. The triple mutants also flowered very early under long day conditions and set very few seeds due to incomplete male sterility. These data indicate that phytochromes play an important role in maximizing photosynthetic abilities during the vegetative growth stage in rice.internodal elongation ͉ mutant ͉ phytochrome ͉ photoreceptor

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confidence: 99%

Phytochromes are the sole photoreceptors for perceiving red/far-red light in rice

Takano

Inagaki

Xie

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

125

115

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“…There are a number of known mutants in which linear tetrapyrrole synthesis is disrupted. These include the hy1 and hy2 mutants of Arabidopsis (Koornneef et al, 1980;Davis et al, 1999;Muramoto et al, 1999;Kohchi et al, 2001), the partially-etiolated-in-white-light1 (pew1) and pew2 mutants of tobacco (Nicotiana plumbaginifolia; Kraepiel et al, 1994), the phytochrome chromophore-deficient1 (pcd1) and pcd2 mutants of pea (Pisum sativum; Weller et al, 1996Weller et al, , 1997, the aurea (au) and yellow-green2 (yg-2) mutants of tomato (Lycopersicon esculentum; Koornneef et al, 1985;Terry and Kendrick, 1996), the photoperiodic sensitive5 (se5) mutant of rice (Oryza sativa; Yokoo and Okuno, 1993;Izawa et al, 2000), and the elongated mesocotyl1 (elm1) mutant of maize (Sawers et al, 2002). PFB is synthesized from 5-aminolevulinic acid, a precursor to both heme and chlorophyll (Elich and Lagarias, 1987).…”

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TheElm1(ZmHy2) Gene of Maize Encodes a Phytochromobilin Synthase

et al. 2004

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The light insensitive maize (Zea mays) mutant elongated mesocotyl1 (elm1) has previously been shown to be deficient in the synthesis of the phytochrome chromophore 3E-phytochromobilin (PΦB). To identify the Elm1 gene, a maize homolog of the Arabidopsis PΦB synthase gene AtHY2 was isolated and designated ZmHy2. ZmHy2 encodes a 297-amino acid protein of 34 kD that is 50% identical to AtHY2. ZmHY2 was predicted to be plastid localized and was targeted to chloroplasts following transient expression in tobacco (Nicotiana plumbaginifolia) leaves. Molecular mapping indicated that ZmHy2 is a single copy gene in maize that is genetically linked to the Elm1 locus. Sequence analysis revealed that the ZmHy2 gene of elm1 mutants contains a single G to A transition at the 3′ splice junction of intron III resulting in missplicing and premature translational termination. However, flexibility in the splicing machinery allowed a small pool of in-frame ZmHy2 transcripts to accumulate in elm1 plants. In addition, multiple ZmHy2 transcript forms accumulated in both wild-type and elm1 mutant plants. ZmHy2 splice variants were expressed in Escherichia coli and products examined for activity using a coupled apophytochrome assembly assay. Only full-length ZmHY2 (as defined by homology to AtHY2) was found to exhibit PΦB synthase activity. Thus, the elm1 mutant of maize is deficient in phytochrome response due to a lesion in a gene encoding phytochromobilin synthase that severely compromises the PΦB pool.

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“…Mutations at the au2 locus in tomato give rise to a defective phenotype that fits well what would be expected from a phytochrome-deficient mutant. Chl content, seed germination, anthocyanin accumulation and hypocotyl elongation were altered (11). The au mutant line W616 has been used in several recent studies to ask questions about phytochrome action ( 17,21).…”

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confidence: 99%

“…The abundance of Chl was closely correlated with that of one of its major apoproteins, LHC(II), during greening ofwild type and several Chl-deficient mutants of maize (9). The au mutation in tomato apparently affects the levels of both phytochrome and Chl (11 Koornneef, Wageningen) were obtained from ripe fruits of greenhouse-grown plants, treated with 0.3% hypochlorite for 20 min, and allowed to dry. Seeds were treated with 0.1% hypochlorite for 30 min and then imbibed in deionized water for 4 h. Prior to imbibition, a small hole was made in the coat of each seed.…”

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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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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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Photomorphogenic Responses of Long Hypocotyl Mutants of Tomato

Cited by 133 publications

References 16 publications

Phytochromes are the sole photoreceptors for perceiving red/far-red light in rice

Phytochromes are the sole photoreceptors for perceiving red/far-red light in rice

TheElm1(ZmHy2) Gene of Maize Encodes a Phytochromobilin Synthase

Altered Phytochrome Regulation of Greening in an aurea Mutant of Tomato

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