Phytochrome and Its Control of Plant Growth and Development

Siegelman, H. W.; Hendricks, S. B.

doi:10.1002/9780470122716.ch1

Cited by 10 publications

(3 citation statements)

References 74 publications

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“…Although some studies have used energy units to measure R and FR fluxes (Salisbury, 1981;Taylorson and Borthwick, 1969), most studies have used photon fluxes because photons were known to be the driving factor for phytochrome responses as far back as 1964 (Butler et al, 1964;Siegelman and Hendricks, 1964). This is also described by the Stark-Einstein Law/photochemical equivalence law (Roth, 2001).…”

Section: Effect Of Wavelength Range On the R:fr Ratiomentioning

confidence: 99%

Far-red Fraction: An Improved Metric for Characterizing Phytochrome Effects on Morphology

Kusuma¹,

Bugbee²

2021

J. Amer. Soc. Hort. Sci.

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Phytochrome, a well-studied photoreceptor in plants, primarily absorbs in the red (R) and far-red (FR) regions and is responsible for the perception of shade and subsequent morphological responses. Experiments performed in controlled environments have widely used the R:FR ratio to simulate the natural environment and used phytochrome photoequilibrium (PPE) to simulate the activity of phytochrome. We review why PPE may be an unreliable metric, including differences in weighting factors, multiple phytochromes, nonphotochemical reversions, intermediates, variations in the total pool of phytochrome, and screening by other pigments. We suggest that environmental signals based on R and FR photon fluxes are a better predictor of plant shape than the more complex PPE model. However, the R:FR ratio is nonintuitive and can approach infinity under electric lights, which makes it difficult to extrapolate from studies in controlled environments to the field. Here we describe an improved metric: the FR fraction (FR/R+FR) with a range from 0 to 1. This is a more intuitive metric both under electric lights and in the field compared with other ratios because it is positively correlated with phytochrome-mediated morphological responses. We demonstrate the reliability of this new metric by reanalyzing previously published data.

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Section: Effect Of Wavelength Range On the R:fr Ratiomentioning

confidence: 99%

Far-red Fraction: An Improved Metric for Characterizing Phytochrome Effects on Morphology

Kusuma¹,

Bugbee²

2021

J. Amer. Soc. Hort. Sci.

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“…Plants have evolved a remarkable capacity to track and respond to fluctuations of light environment. The process of photomorphogenesis is facilitated through several photoreceptors, which include phytochromes (Siegelman & Hendricks 1964;Mullen, Weinig & Hangarter 2006;Rockwell, Su & Lagarias 2006), small families of cryptochromes (Ahmad & Cashmore 1993), phototropins (Briggs et al 2001) and other blue light receptors. The type I phytochromes (Phy) accumulate in etiolated seedlings and are degraded upon light exposure, whereas the type II phytochromes are relatively stable in light.…”

Section: Introductionmentioning

confidence: 99%

Involvement of phytochrome A in suppression of photomorphogenesis in rice seedling grown in red light

Roy

Tripathy

2013

Plant Cell & Environment

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Plants have evolved a remarkable capacity to track and respond to fluctuations of light quality and intensity that influence photomorphogenesis facilitated through several photoreceptors, which include a small family of phytochromes. Rice seedlings grown on germination paper in red light for 48 h having their shoot bottom exposed had suppressed photomorphogenesis and were deficient in chlorophyll. Seedlings grown under identical light regime having their shoot bottom covered were green and accumulated chlorophyll. Further, etiolated seedlings with their shoot bottom exposed, when grown in 4 min red/far-red cycles for 48 h, accumulated chlorophyll demonstrating the reversal of suppression of photomorphogenesis by far-red light. It implicates the involvement of phytochrome. Immunoblot analysis showed the persistence of photolabile phytochrome A protein for 48 h in seedlings grown in red light with their shoot bottom exposed, suggesting its involvement in suppression of photomorphogenesis. This was further corroborated in phyA seedlings that turned green when grown in red light having their shoot bottom exposed. Calmodulin (CaM) antagonist N-(6-aminohexyl)-5-chloro-1-napthalene sulphonamide or trifluoperazine substantially restored photomorphogenesis both in the wild type (WT) and phyA demonstrating the involvement of CaM-dependent kinases in the down-regulation of the greening process. Results demonstrate that red light-induced suppression of photomorphogenesis, perceived in the shoot bottom, is a red high irradiance response of PhyA.

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“…The plant sensory photoreceptor, phytochrome, was first discovered in the 1960s ( Siegelman and Hendricks, 1964 ). Five members of this red/far-red photoreceptor family, phyA-phyE, are encoded by the nuclear genome in Arabidopsis thaliana ( Briggs and Olney, 2001 ).…”

Section: Phytochromesmentioning

confidence: 99%

How and why do root apices sense light under the soil surface?

Yokawa

Wan

et al. 2015

Front. Plant Sci.

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Light can penetrate several centimeters below the soil surface. Growth, development and behavior of plant roots are markedly affected by light despite their underground lifestyle. Early studies provided contrasting information on the spatial and temporal distribution of light-sensing cells in the apical region of root apex and discussed the physiological roles of plant hormones in root responses to light. Recent biological and microscopic advances have improved our understanding of the processes involved in the sensing and transduction of light signals, resulting in subsequent physiological and behavioral responses in growing root apices. Here, we review current knowledge of cellular distributions of photoreceptors and their signal transduction pathways in diverse root tissues and root apex zones. We are discussing also the roles of auxin transporters in roots exposed to light, as well as interactions of light signal perceptions with sensing of other environmental factors relevant to plant roots.

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Phytochrome and Its Control of Plant Growth and Development

Cited by 10 publications

References 74 publications

Far-red Fraction: An Improved Metric for Characterizing Phytochrome Effects on Morphology

Far-red Fraction: An Improved Metric for Characterizing Phytochrome Effects on Morphology

Involvement of phytochrome A in suppression of photomorphogenesis in rice seedling grown in red light

How and why do root apices sense light under the soil surface?

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