Phototropism: Some History, Some Puzzles, and a Look Ahead

Briggs, Winslow R.

doi:10.1104/pp.113.230573

Cited by 104 publications

(108 citation statements)

References 117 publications

Supporting

Mentioning

100

Contrasting

Unclassified

Order By: Relevance

“…Even under red light pretreatment, the first positive phototropism was severely impaired in the phyA phyB double mutant, and the onset of second positive phototropism was delayed (Janoudi et al, 1997). Phy signaling appears to be involved in the light adaptation mechanism of phot1 signaling (Briggs, 2014).…”

Section: Introductionmentioning

confidence: 99%

Arabidopsis ROOT PHOTOTROPISM2 Contributes to the Adaptation to High-Intensity Light in Phototropic Responses

et al. 2015

View full text Add to dashboard Cite

Living organisms adapt to changing light environments via mechanisms that enhance photosensitivity under darkness and attenuate photosensitivity under bright light conditions. In hypocotyl phototropism, phototropin1 (phot1) blue light photoreceptors mediate both the pulse light-induced, first positive phototropism and the continuous light-induced, second positive phototropism, suggesting the existence of a mechanism that alters their photosensitivity. Here, we show that light induction of ROOT PHOTOTROPISM2 (RPT2) underlies photosensory adaptation in hypocotyl phototropism of Arabidopsis thaliana. rpt2 loss-offunction mutants exhibited increased photosensitivity to very low fluence blue light but were insensitive to low fluence blue light. Expression of RPT2 prior to phototropic stimulation in etiolated seedlings reduced photosensitivity during first positive phototropism and accelerated second positive phototropism. Our microscopy and biochemical analyses indicated that blue light irradiation causes dephosphorylation of NONPHOTOTROPIC HYPOCOTYL3 (NPH3) proteins and mediates their release from the plasma membrane. These phenomena correlate closely with the desensitization of phot1 signaling during the transition period from first positive phototropism to second positive phototropism. RPT2 modulated the phosphorylation of NPH3 and promoted reconstruction of the phot1-NPH3 complex on the plasma membrane. We conclude that photosensitivity is increased in the absence of RPT2 and that this results in the desensitization of phot1. Light-mediated induction of RPT2 then reduces the photosensitivity of phot1, which is required for second positive phototropism under bright light conditions.

show abstract

Section: Introductionmentioning

confidence: 99%

Arabidopsis ROOT PHOTOTROPISM2 Contributes to the Adaptation to High-Intensity Light in Phototropic Responses

et al. 2015

View full text Add to dashboard Cite

show abstract

“…According to the Cholodny-Went theory, directed growth of plant organs such as phototropic or gravitropic growth is the result of an auxin gradient that is established across the organ (Briggs, 2014). To test if hypoxia alters auxin levels we employed the DII-VENUS reporter line to study auxin activity at the root tip (Fig.…”

Section: Hypoxia Triggers Asymmetric Auxin Distribution At the Root Apexmentioning

confidence: 99%

Root Bending Is Antagonistically Affected by Hypoxia and ERF-Mediated Transcription via Auxin Signaling

Eysholdt-Derzsó

Sauter

2017

Plant Physiol.

View full text Add to dashboard Cite

ORCID ID: 0000-0002-7370-643X (M.S.).When plants encounter soil water logging or flooding, roots are the first organs to be confronted with reduced gas diffusion resulting in limited oxygen supply. Since roots do not generate photosynthetic oxygen, they are rapidly faced with oxygen shortage rendering roots particularly prone to damage. While metabolic adaptations to low oxygen conditions, which ensure basic energy supply, have been well characterized, adaptation of root growth and development have received less attention. In this study, we show that hypoxic conditions cause the primary root to grow sidewise in a low oxygen environment, possibly to escape soil patches with reduced oxygen availability. This growth behavior is reversible in that gravitropic growth resumes when seedlings are returned to normoxic conditions. Hypoxic root bending is inhibited by the group VII ethylene response factor (ERFVII) RAP2.12, as rap2.12-1 seedlings show exaggerated primary root bending. Furthermore, overexpression of the ERFVII member HRE2 inhibits root bending, suggesting that primary root growth direction at hypoxic conditions is antagonistically regulated by hypoxia and hypoxia-activated ERFVIIs. Root bending is preceded by the establishment of an auxin gradient across the root tip as quantified with DII-VENUS and is synergistically enhanced by hypoxia and the auxin transport inhibitor naphthylphthalamic acid. The protein abundance of the auxin efflux carrier PIN2 is reduced at hypoxic conditions, a response that is suppressed by RAP2.12 overexpression, suggesting antagonistic control of auxin flux by hypoxia and ERFVII. Taken together, we show that hypoxia triggers an escape response of the primary root that is controlled by ERFVII activity and mediated by auxin signaling in the root tip.

show abstract

“…Tropisms are important for plants, which as sessile organisms, utilize these movements to respond to external stimuli (Kaufman et al 1987;Whippo and Hangarter 2004). Typically, in ground studies, plants respond to blue-light photostimulation positively (growth towards the light) in shoots, and negatively (growth away from the light source) in roots (Kutschera and Briggs 2012;Briggs 2014;Liscum et al 2014). Recently, a positive red-light-based phototropic response in roots mediated by phytochromes has been observed and characterized Molas and Kiss 2008), in addition to positive hypocotyl phototropic response to red light in the conditions of microgravity (Millar et al 2010).…”

Section: Introductionmentioning

confidence: 99%

A novel blue-light phototropic response is revealed in roots of Arabidopsis thaliana in microgravity

Vandenbrink

Herranz

Medina

et al. 2016

Planta

View full text Add to dashboard Cite

Main conclusion Blue-light positive phototropism in roots is masked by gravity and revealed in conditions of microgravity. In addition, the magnitude of red-light positive phototropic curvature is correlated to the magnitude of gravity.Due to their sessile nature, plants utilize environmental cues to grow and respond to their surroundings. Two of these cues, light and gravity, play a substantial role in plant orientation and directed growth movements (tropisms). However, very little is currently known about the interaction between light-(phototropic) and gravity (gravitropic)-mediated growth responses. Utilizing the European Modular Cultivation System on board the International Space Station, we investigated the interaction between phototropic and gravitropic responses in three Arabidopsis thaliana genotypes, Landsberg wild type, as well as mutants of phytochrome A and phytochrome B. Onboard centrifuges were used to create a fractional gravity gradient ranging from reduced gravity up to 1g. A novel positive blue-light phototropic response of roots was observed during conditions of microgravity, and this response was attenuated at 0.1g. In addition, a red-light pretreatment of plants enhanced the magnitude of positive phototropic curvature of roots in response to blue illumination. In addition, a positive phototropic response of roots was observed when exposed to red light, and a decrease in response was gradual and correlated with the increase in gravity. The positive red-light phototropic curvature of hypocotyls when exposed to red light was also confirmed. Both red-light and blue-light phototropic responses were also shown to be affected by directional light intensity. To our knowledge, this is the first characterization of a positive blue-light phototropic response in Arabidopsis roots, as well as the first description of the relationship between these phototropic responses in fractional or reduced gravities.Correspondence to: John Z. Kiss. Electronic supplementary material The online version of this article

show abstract

Phototropism: Some History, Some Puzzles, and a Look Ahead

Cited by 104 publications

References 117 publications

Arabidopsis ROOT PHOTOTROPISM2 Contributes to the Adaptation to High-Intensity Light in Phototropic Responses

Arabidopsis ROOT PHOTOTROPISM2 Contributes to the Adaptation to High-Intensity Light in Phototropic Responses

Root Bending Is Antagonistically Affected by Hypoxia and ERF-Mediated Transcription via Auxin Signaling

A novel blue-light phototropic response is revealed in roots of Arabidopsis thaliana in microgravity

Contact Info

Product

Resources

About