Photosensory mechanisms in the lettuce seedling hypocotyl

Turner, M. R.; Vince, Daphne

doi:10.1007/bf00396429

Cited by 45 publications

(19 citation statements)

References 17 publications

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“…Turner and Vince (22) have recently suggested that in lettuce seedlings two different photoreceptors exert control on anthocyanin synthesis through different photosensitive pigments.…”

Section: Vred Light and Rna Polymerasementioning

confidence: 99%

Deoxyribonucleic Acid-dependent Ribonucleic Acid Polymerase Activity of Nuclei and Plastids from Etiolated Peas and their Response to Red and Far Red Light in Vivo

Bottomley

1970

Plant Physiol.

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Common wealth Scien tific a)1d Inidlustrial ResearchABSTRlACT DNA-depenidenit RINA polymiierase activity has lbeell found in both the iucleci anid etioplasts of (lark-grownvi pea seedIiiigs (Pisurn satirurn). Althliotugh thiese en-izymiies lhad simiiilar over-all clharacteristics witlh respect to silIstrate, pll, anid iinhiibitor responises, tlhey could be distiniguiished by tlhei differenit sensitivities to sonicationi.Brief irradiation of the seedlings witlh red liglht resulted in ani increase in the activity of botli the iutnclear anid plastid enizymiies, btut the timiie couirse of this response shiowedi it to be too slow to be considered aii early-resuilt of phyitocliromiie control of imietabolismii. Far red lighit follow-ving red treatient largely prevenited the inierease in thie activity of tile inuiclear eizym-ltie. The plastid enzymie responded to far red light in a imianniier simiiilar to its responise to red liglht so that no reversal was observ-ed wlheni far redl treatmiienit followed re(l. The emission intensities of the two sources are shown in Figure 1.Isolation of Nuclei and Plastids. During isolation and assay, all solutions contained 10 mm mercaptoethanol and 25 g,g ml chloramphenicol. The chloramphenicol had no detectable effect on the enzyme activity. During isolation all solutions were kept at 0 to 4 C. Approximately 10 g of terminal buds of the etiolated peas were harvested, cooled in ice, and chopped with a razor blade in 20 ml of 0.05 M tris (pH 8.3 at 4 C) containing 10 mm MgCI2 and 0.4 mI sucrose, by the method of Spencer and Wildman (20). After filtration through two layers of Miracloth (Chicopee Mills, Inc.), the sLIspension was centrifuged at 700 g for 10 min. The pellet was resuspended in 5 ml of the 0.4 M sucrose-tris-MgCl. chopping buffer and layered on a discontinuous sucrose gradient consisting of 5 ml each of 1.4 M, 1.1 M, 1.0 M, 0.8 M, and 0.6 M sucrose in 0.05 M tris (pH 8.3 at 4 C) containing 10 mM MgC12. The gradient was centrifuged at 10OOg for 15 min, after which time the intact etioplasts were recovered from the 1.0 M sucrose layer and the nuclei from the pellet at the bottom of the tube. Carotenoid Estimation. A 0.2-ml aliquot of the plastid suspension was diluted with 0.8 ml of acetone, and the solution was shaken, warmed, and centrifuged to clarify it. The absorbance of the supernatant at 473 nm was determined, and the carotenoid content was calculated assuming Ell,c to be 2500 (6).

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“…Turner and Vince (22) have recently suggested that in lettuce seedlings two different photoreceptors exert control on anthocyanin synthesis through different photosensitive pigments.…”

Section: Vred Light and Rna Polymerasementioning

confidence: 99%

Deoxyribonucleic Acid-dependent Ribonucleic Acid Polymerase Activity of Nuclei and Plastids from Etiolated Peas and their Response to Red and Far Red Light in Vivo

Bottomley

1970

Plant Physiol.

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“…Although many studies have shown that phytochrome mediates a significant part of this response to light (17,20,21,28,29), there are several lines of evidence indicating the involvement of a bluelight receptor, distinct from phytochrome, in the control of stem growth (10,14,26,27). Meijer (19) has shown that blue irradiation rapidly inhibits the growth of etiolated cucumber seedlings, whereas, red and far-red irradiations only slowly affect growth after a lag of 60 min.…”

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confidence: 99%

“…In contrast, with continuous and end-of-day irradiation experiments, Wildermann et al (29) found no indication of the involvement of a blue-light photoreceptor in the control of Sinapis hypocotyl growth. Although coarse-resolution measurements suggest that a rapid response to blue light may also occur in other species (14,27), high-resolution measurements have been 'This research was supported by National Science Foundation Grant PCM 78-03244 to Dr. Paul Green.…”

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confidence: 99%

Rapid Suppression of Growth by Blue Light

Cosgrove¹

1981

Plant Physiol.

227

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The inhibition of stem elongation in dark-grown seedlings by blue Light was studied with marking techniques and with a high-resolution, growthmeasuring apparatus. Blue light rapidly suppresses growth in a variety of cultivated species. In some species, the inhibition persists only during the period of irradiation, after which time growth quickly returns to the high dark rate, whereas, in other species, the light response has an additional long-term component which lasts for at least several hours in the dark. The long-term inhibition may be mediated by phytochrome, whereas the rapid, short-term component is specific to a blue-light receptor.The rapid inhibition of growth in cucumber (Cucumis sativus L.) requires high-energy blue irradiation, which is perceived directly by the growing region of the hypocotyl and inhibits all regions below the hook to the same extent. Detailed investigation of the kinetics of the inhibition in cucumber and in sunflower (Heliantiws anus L.) shows that, after a short lag period (20 to 30 seconds in cucumber, 60 to 70 seconds in sunflower), the growth rate declines in an exponential fashion to a lower rate, with a half-time of 15 to 25 seconds in cucumber and 90 to 150 seconds in sunflower. Excision of the hypocotyl greatly reduces the sensitivity of the growth rate to blueUght inhibition. Because of the rapid kinetics, the blue-Ught photoreceptor cannot affect celi enlargement by altering the supply of growth hormone or the sensitivity to hormones but probably operates more directly either on the biochemical process which loosens cell walls or on celi turgor.

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“…2, a and b). Because release of inhibition from both blue and orange light required a similar time period, this indicates the two peaks of the action spectrum represent absorption by a single photoreceptor (15). (Table I).…”

Section: Resultsmentioning

confidence: 92%