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Arend-Jan Both, Bruce Bugbee, Chieri Kubota, Roberto G. Lopez, Cary Mitchell, Erik S. Runkle, and Claude Wallace

. Example of the proposed product label for a light-emitting diode (LED) lamp specifically designed for plant growth applications. PSS is the phytochrome photostationary state, using values from Sager et al. (1988) , which is a dimensionless ratio indicated

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Diego A. Mata and Javier F. Botto

spectrum by specialized photoreversible receptors called phytochromes. The action of the phytochromes is a function of the relative amounts of the active and the inactive forms (Pfr and Pr, respectively) established in the plant tissues, and it positively

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Michael P. Dzakovich, Celina Gómez, Mario G. Ferruzzi, and Cary A. Mitchell

properties of edible plant tissues. Alterations in metabolic flux in response to light are mediated by a host of proteins including the phytochromes, cryptochromes, phototropins, and UVR8, among others ( Galvão and Fankhauser, 2015 ; Gyula et al., 2003

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William R. Okie and Bryan Blackburn

greenhouses using natural daylight. Erez et al. (1966) suggested that peach leaf budbreak is phytochrome-dependent and thus needs a light stimulus in contrast to flower budbreak, which was inhibited by light during budbreak in their study. Phytochrome is a

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D. Michael Glenn and G.J. Puterka

and Loughrin, 2004 ) through phytochrome-mediated processes. Colored netting, while reducing light, can also increase yield ( Shahak et al., 2004 ). Despite the increased light levels in the canopy from reflective films, increased fruit size is

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Takanori Takeuchi, Miwako Cecile Matsushita, Soichiro Nishiyama, Hisayo Yamane, Kiyoshi Banno, and Ryutaro Tao

, respectively ( Table 4 ). These genes were annotated based on a BLAST search and five genes encoded transcription factors. The annotations indicated that MD09G1146000 , MD09G1009100 , MD14G1126900 , MD16G1140800 , and MD15G1369700 encode PHYTOCHROME

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Kevin R. Cope and Bruce Bugbee

ratio and phytochrome photoequilbria). These results were reviewed by Yorio et al. (1998) . Later, Dougher and Bugbee (2001a) examined the effects of blue light on growth and development of lettuce, soybean, and wheat using high-pressure sodium (HPS

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Gary R. Bachman and Margaret J. McMahon

It is theorized that photomorphogenic reductions in stem elongation are similar to thermomorphogenic plant response, i.e. increased red:far-red light response is similar to –DIF (day temperature < night temperature). The long hypocotyl (hy) mutants of Arabidopsis thaliana Landsberg are phytochrome mutants that are less responsive to light quality than wild type. These include mutants of phytochrome chromophore biosynthesis (hy 1, hy2, hy6), phytochrome B (hy3), blue-light receptor (hy4), and signal transduction (hy5). These mutants were grown in growth chambers with temperatures of 18C day/24C night (–DIF) and 24°C day/18°C night with a 14-h photoperiod. Lighting consisted of both incandescent and fluorescent lamps. Growth measurements of five of the mutants were consistent with reported effects of DIF. The height of these plants were significantly greater in the +DIF regime when compared to –DIF. The hy5 mutant showed little difference in the height measurements of plants grown in either -DIF or +DIF. This mutant has a phytochrome signal transduction deficiency. This result indicates that a functional photoreceptor is required, even in reduced quantities as in the phytochrome chromophore biosynthesis mutants, to signal perception of DIF temperature conditions.

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Sandra L. Barbour, Margaret J. McMahon, John J. Frett, 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.

As a beginning step to determine cytokinin-phytochrome interactions, we developed a strategy utilizing ipt -transgenic tobacco in phytochrome/light treatment investigations. The sour-cc of the ipt gene was Agrobacterium tumefaciens Ti plasmid 15955. This gene encodes for isopentenyl transferase which is an enzyme active in cytokinin biosynthesis.

Ipt -transgenic tobacco cultures (grown on MS medium supplemented with kanamycin but no plant growth regulators) were treated with end-of-day red or far-red light for 15 minutes. After 30 days of treatment, the plant tissue was harvested and either homogenized for SDS-PAGE or fixed for transmission electron microscopic analysis.

Results from immuno-gold labelling using polyclonal antibodies specific to iptase will he used to Indicate the influence of phytochrome on cytokinin activity. Also, structural changes at the ultra-cellular level will be determined.

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E. Mergenthaler, Gy. Bisztray, and D.P. Coyne

As ancestors of higher plants, mosses offer advantages as simple model organisms in studying complex processes. The moss Physcomitrella patens became a powerful model system in the last few years (Cove and Knight, 1993). Adaptation of PEG-mediated DNA uptake procedure has permitted the establishment of efficient molecular genetic approaches. To study possible effects of a Type I phytochrome, the potato phyA gene was introduced into the moss P. patens. Stabile transformants exhibited a range of similar phenotypes (Schaefer et al., 1991). The aim was to differentiate the wild type from the transgenic moss plants with simple, quick measurements providing data suitable for analyzing offspring populations. Ten different morphological and biochemical methods were used to investigate the phenotype in order to choose the best phenotypical category to indicate the presence and the effect of the phytochrome transgene. Two selected strains were used with the most and the least intensive phenotypical features (3*, 29), along with their selfed progenies, as well as progenies from crosses with the nicotinic-acid auxotrophic mutant. The best methods to differentiate between wild type and transgenic plants were the statistical analysis of the number of gametophores, photometric measurement of pigment contents and composition under different light conditions, color evaluation by PC-based vision system, and visual observation of morphogenetic changes. Our investigations support that the potato phytochrome transgene has a pleiotropic effect in the moss P patens. The methods used would be applicable for the characterization of mosses with different transgenes.