ACTION SPECTRUM FOR ENHANCEMENT OF PHOTOTROPISM BY <i>Arabidopsis thaliana</i> SEEDLINGS

Janoudi, Abdul-kader; Poff, Kenneth L.

doi:10.1111/j.1751-1097.1992.tb02218.x

Cited by 34 publications

(12 citation statements)

References 22 publications

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“…Therefore, it is evident that a form of interaction occurs between these two distinct sensory-response systems. Previous studies have shown that enhancement is maximized when the red-light stimulus precedes the blue-light phototropic stimulus by 2 h (Janoudi and Poff, 1991), and it was suggested that phytochrome affects the phototropic response by modulating a component of the blue-light signal transduction sequence (Janoudi and Poff, 1992). It is also possible that the effect of phytochrome on phototropism is indirect.…”

Section: Dlscusslonmentioning

confidence: 93%

“…F40/CW [General Electric]; 600-700 nm with maximum intensity at 658 nm) given from above 2 h prior to the phototropic stimulus (Janoudi and Poff, 1991). For most experiments, the red-light intensity was saturating for the enhancement response (Janoudi and Poff, 1992). When necessary, the intensity of the red-light treatment was varied by the addition of metal neutral density screens.…”

Section: Phototropism Experimentsmentioning

confidence: 99%

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Phytochrome A Regulates Red-Light Induction of Phototropic Enhancement in Arabidopsis

1996

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Phytochrome A (phyA) and phytochrome B photoreceptors have distinct roles in the regulation of plant growth and development. Studies using specific photomorphogenic mutants and transgenic plants overexpressing phytochrome have supported an evolving picture in which phyA and phytochrome B are responsive to continuous far-red and red light, respectively. Photomorphogenic mutants of Arabidopsis thaliana that had been selected for their inability to respond to continuous irradiance conditions were tested for their ability to carry out red-light-induced enhancement of phototropism, which is an inductive phytochrome response. We conclude that phyA is the primary photoreceptor regulating this response and provide evidence suggesting that a common regulatory domain in the phyA polypeptide functions for both high-irradiance and inductive phytochrome responses.

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Section: Dlscusslonmentioning

confidence: 93%

Section: Phototropism Experimentsmentioning

confidence: 99%

Phytochrome A Regulates Red-Light Induction of Phototropic Enhancement in Arabidopsis

1996

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“…The time threshold for second positive curvature is reduced by exposure to red light before unilateral blue light (62). Even in the absence of a red light pulse, the phyA phyB double mutant requires prolonged exposures to blue light (compared to the wild type) to exhibit second positive curvature (58) (Fig.…”

Section: ϫ2mentioning

confidence: 96%

“…A pulse of red light given 2 h before unilateral blue light is perceived by phytochromes and enhances first positive curvature (62). This enhancement is reduced in the phyA and phyB mutants (63,64) and absent in the phyA phyB double mutant (58).…”

Section: ϫ2mentioning

confidence: 99%

Phytochromes, Cryptochromes, Phototropin: Photoreceptor Interactions in Plants

Casal¹

2007

Photochemistry and Photobiology

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In higher plants, natural radiation simultaneously activates more than one photoreceptor. Five phytochromes (phyA through phyD), two cryptochromes (cry1, cry2) and phototropin have been identified in the model species Arabidopsis thaliana. There is light-dependent epistasis among certain photoreceptor genes because the action of one pigment can be affected by the activity of others. Under red light, phyA and phyB are antagonistic, but under far-red light, followed by brief red light, phyA and phyB are synergistic in the control of seedling morphology and the expression of some genes during de-etiolation. Under short photoperiods of red and blue light, cry1 and phyB are synergistic, but under continuous exposure to the same light field the actions of phyB and cry1 become independent and additive. Phototropic bending of the shoot toward unilateral blue light is mediated by phototropin, but cry1, cry2, phyA and phyB positively regulate the response. Finally, cry2 and phyB are antagonistic in the induction of flowering. At least some of these interactions are likely to result from cross talk of the photoreceptor signaling pathways and uncover new avenues to approach signal transduction. Experiments under natural radiation are beginning to show that the interactions create a phototransduction network with emergent properties. This provides a more robust system for light perception in plants. PLANT PHOTORECEPTORSPlants are able to monitor the light environment and perceive signals that modulate growth and development. Seed germination, seedling de-etiolation (i.e. transition from skotomorphogenesis to photomorphogenesis), vegetative growth, organ orientation and the transition to reproductive development are some of the processes profoundly affected by the light environment via nonphotosynthetic light signals. These signals are perceived by a number of photoreceptors:

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“…In general,, R treatments can greatly enhance the phototropic response in primary shoots (Chon & Briggs 1966;Janoudi & Poff 1992;Liu & lino 1996). In Arabidopsis, phytochrome activation by R has been suggested to result in the production of an unknown substance that functions to amplify the phototropic response (Janoudi & Poff 1991).…”

Section: Phytochrome and Phototropismmentioning

confidence: 99%

Gravity, light and plant form

Hangarter

1997

Plant Cell & Environment

182

124

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Plants have evolved highly sensitive and selective mechanisms that detect and respond to various aspects of their environment. As a plant develops, it integrates the environmental information perceived by all of its sensory systems and adapts its growth to the prevailing environmental conditions. Light is of critical importance because plants depend on it for energy and, thus, survival. The quantity, quality and direction of light are perceived by several different photosensory systems that together regulate nearly all stages of plant development, presumably in order to maintain photosynthetic efficiency. Gravity provides an almost constant stimulus that is the source of critical spatial information about its surroundings and provides important cues for orientating plant growth. Gravity plays a particularly important role during the early stages of seedling growth by stimulating a negative gravitropic response in the primary shoot that orientates it towards the source of light, and a positive gravitropic response in the primary root that causes it to grow down into the soil, providing support and nutrient acquisition. Gravity also influences plant form during later stages of development through its effect on lateral organs and supporting structures. Thus, the final form of a plant depends on the cumulative effects of light, gravity and other environmental sensory inputs on endogenous developmental programs. This article is focused on developmental interactions modulated by light and gravity.

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ACTION SPECTRUM FOR ENHANCEMENT OF PHOTOTROPISM BY Arabidopsis thaliana SEEDLINGS

Cited by 34 publications

References 22 publications

Phytochrome A Regulates Red-Light Induction of Phototropic Enhancement in Arabidopsis

Phytochrome A Regulates Red-Light Induction of Phototropic Enhancement in Arabidopsis

Phytochromes, Cryptochromes, Phototropin: Photoreceptor Interactions in Plants

Gravity, light and plant form

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