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Sandra L. Barbour and Dennis R. Decoteau

Similarities exist between the effects of phytochrome and cytokinins on plant growth and development (e.g., chloroplast development. amaranthin synthesis, seed germination, photomorphogenesis). It is unclear. however, if and how these two systems interact.

To determine the effects of phytochrome activity on cytokinin synthesis and ultracellular plant development, we utilized tobacco transformed with the Agrobacterium tumefaciens isopentenyl transferase (ipt) gene. This gene encodes for isopentenyl transferase (iptase) which is an enzyme active in cytokinin biosysthesis.

Ipt-transgenic tobacco cultures were treated with end-of-day red or far-red light for 15 minutes. After 15-30 days of treatment, the plant tissue was harvested and ipt expression was verified by SDS-PAGE and western blot analysis. Polyclonal antibodies specific to iptase were used as a primary antibody. Colloidal gold conjugated to goat. anti-rabbit antiserum served as an electron dense, secondary antibody and a probe to light-influenced iptase synthesis and distribution within the cell.

A Hitachi 600AB transmission electron microscope was used to determine the influence of phytochrome/light treatments on the ultrastructure of ipr-transgenic cells.

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David L. Bubenheim, Bruce Bugbee, and Frank B. Salisbury

Abstract

Radiation in controlled environments was characterized using fluorescent and various high-intensity-discharge (HID) lamps, including metal halide, low-pressure sodium, and high-pressure sodium as the radiation source. The effects of water, glass, or Plexiglas filters on radiation were determined. Photosynthetic photon flux (PPF, 400 to 700 nm), spectra (400 to 1000 nm), shortwave radiation (285 to 2800 nm), and total radiation (300 to 100,000 nm) were measured, and photosynthetically active radiation (PAR, 400 to 700 nm) and longwave radiation (2800 to 100,000 nm) were calculated. Measurement of PPF alone was not an adequate characterization of the radiation environment. Total radiant flux varied among lamp types at equal PPF. HID lamps provided a lower percentage of longwave radiation than fluorescent lamps, but, when HID lamps provided PPF levels greater than that possible with fluorescent lamps, the amount of longwave radiation was high. Water was the most effective longwave radiation filter. Glass and Plexiglas similarly filtered longwave more than shortwave radiation, but transmission of nonphotosynthetic shortwave radiation was less with Plexiglas than glass. The filter materials tested would not be expected to influence photomorphogenesis because radiation in the action spectrum of phytochrome was not altered, but this may not be the only pigment involved.

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Gary W. Stutte

photosynthesis ( McCree, 1972 ) to allow the photosynthetic efficiency of a given wavelength to be evaluated as well. These well-defined parameters allow the spectra to be optimized for both photosynthesis and photomorphogenesis. Table 2. Spectral files of

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Theoharis Ouzounis, Eva Rosenqvist, and Carl-Otto Ottosen

state of cry1 and cry2 reserves blue light-induced responses ( Banerjee et al., 2007 ; Bouly et al., 2007 ; Folta and Maruhnich, 2007 ). All photoreceptors mediate the light-dependent development of plants, a process called photomorphogenesis. The

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Aisu Gu, Wenfang Liu, Chao Ma, Jin Cui, Richard J. Henny, and Jianjun Chen

, M. 2008 Optimization of factors affecting organogenesis and somatic embryogenesis of Anthurium andreanum Lind. ‘Tera’ Propag. Ornam. Plants 8 198 203 Briggs, W.R. Olney, M.A. 2001 Photoreceptors in plant photomorphogenesis to date, five

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Kevin R. Cope and Bruce Bugbee

, R.C. 1992 Evaluation of light-emitting diode characteristics for a space-based plant irradiation source Adv. Space Res. 12 141 149 Britz, S.J. Sager, J.C. 1990 Photomorphogenesis and photoassimilation in soybean and sorghum grown under broad spectrum

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Baniekal Hiremath Gangadhar, Raghvendra Kumar Mishra, Gobinath Pandian, and Se Won Park

., 1995 ). Plant responses to various effects of light occurs in terms of multiple developmental processes such as seed germination, seedling photomorphogenesis, leaf size, leaf anatomy, plant height, flowering and fruit development, and altered primary

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Aneta K. Studzinska, David S. Gardner, James D. Metzger, David Shetlar, Robert Harriman, and T. Karl Danneberger

HortScience 38 113 116 Tegg, R.S. Lane, P.A. 2004 Shade performance of a range of turfgrass species improved by trinexapac-ethyl Aust. J. Exp. Agr. 44 939 945 Wherley, B.G. Gardner, D.S. Metzger, J.D. 2005 Tall fescue photomorphogenesis as influenced by

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Miguel Urrestarazu, Cinthia Nájera, and María del Mar Gea

-intensity light is frequently reported as a factor for photoinhibition ( Long et al., 1994 ). In addition, the effect of low light levels on plant growth and photomorphogenesis is well known; for example, they can lead to increased specific leaf area (SLA) and

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Robert C. Morrow

photomorphogenesis of pepper plants under red light-emitting diodes with supplemental blue or far-red lighting J. Amer. Soc. Hort. Sci. 120 808 813 Bula, R.J. Morrow, R.C. Tibbitts, T.W. Barta, D.J. Ignatius, R