Action spectrum for light-induced formation of adventitious shoots in hairy roots of horseradish

Saitou, Tsutomu; Tachikawa, Yoshinobu; Kamada, Hiroshi; Watanabe, Masakatsu; Harada, Hiroshi

doi:10.1007/bf00198224

Cited by 17 publications

(8 citation statements)

References 16 publications

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“…Therefore, phyB and blue light photoreceptors may have some interaction in response to blue light. A similar finding was reported for the phytochrome-mediated induction of adventitious shoot formation in hairy roots of horseradish (24), where the phytochrome photo-excitation response was thought to be modified by blue light photoreceptor photo-excitation.…”

Section: Characteristics Of the Photoperception Properties Of Phya Ansupporting

confidence: 83%

“…Several photoreversible blue light responses have been described in higher plants. Regulation of coleoptile elongation in rice (19), adventitious shoot formation in horseradish (24), and induction of CAB gene expression in Arabidopsis (12) were shown to be blue/FR reversible. They have been thought to be attributed to phytochrome but the phytochrome species responsible for the blue/FR reversibility have not been clearly identified, yet.…”

Section: Discussionmentioning

confidence: 99%

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Phytochrome-Mediated Inhibition of Coleoptile Growth in Rice: Age-dependency and Action Spectra†

Xie¹,

Shinomura²,

Inagaki³

et al. 2007

Photochemistry and Photobiology

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Phytochrome has been shown to be the major photoreceptor involved in the photo-inhibition of coleoptile growth in Japonica-type rice (Oryza sativa L.). We have characterized this typical photomorphogenetic response of rice using mutants deficient in phytochrome A (phyA) and phytochrome B (phyB) and with respect to age-dependency and action spectra. Seedlings were irradiated with a pulse of light 40 h or 80 h after germination (i.e. at an early or late developmental stage) and the final coleoptile length of these seedlings was determined. A saturating pulse of red light (R) had a stronger effect when it was given in the late stage than in the early stage. It was found that the photoinhibition is mediated by both the phyA and the phyB in the late stage but predominantly by phyB in the early stage. Consistent with many other reported responses, the photo-inhibition in the phyA mutant, which was observed in the early and late developmental stages and is thought to be mediated mainly by phyB, occurred in the low-fluence range (10(1)-10(3) micromol m(-2)) of R and was far-red-light (FR)-reversible; the photo-inhibition in the phyB mutant, which was observed in the late developmental stage and is thought to be mediated mainly by phyA, occurred in the very-low-fluence range (10(-2)-10(0) micromol m(-2)) and was FR-irreversible. The action spectra (350-800 nm at 50 nm intervals) obtained at the two developmental stages using phyA and phyB mutants indicated that both the phyB-mediated low-fluence response and the phyA-mediated very-low-fluence response have a major peak at 650 nm and a minor peak at 400 nm.

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Section: Characteristics Of the Photoperception Properties Of Phya Ansupporting

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Phytochrome-Mediated Inhibition of Coleoptile Growth in Rice: Age-dependency and Action Spectra†

Xie¹,

Shinomura²,

Inagaki³

et al. 2007

Photochemistry and Photobiology

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“…It is thought that the photoirreversible responses are mediated by a unique, blue/UV-A receptor (Kaufman, 1993) or PhyA (Shinomura et al, 1996). Blue/farred reversible regulation of coleoptile elongation in rice (Paul and Furuya, 1973) and adventitious shoot formation in horseradish (Saitou et al, 1993) have also been attributed to phytochrome.…”

Section: Blue-light Effects On Lnduction Of Cab Expressionmentioning

confidence: 99%

Fluence and Wavelength Requirements for Arabidopsis CAB Gene Induction by Different Phytochromes

et al. 1997

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Plants sense many aspects of light in their environment, including its wavelength, duration, intensity, and direction. Photoregulations in plants have been classified into two categories known as the induction reaction and the HIR in terms of fluence and timing of irradiations, and the former is further divided into the VLF response and the LF response Furuya and Schafer, 1996). VLF responses can be initiated by fluences as low as 0.1 nmol m-', whereas LF responses require fluences greater than 1 pmol m-'. HIRs are elicited by prolonged or continuous irradiation that require exposure for hours, and fluences in excess of 10 mmol m-'. Plants monitor their light environment using a number of photoreceptors, the best characterized of which are phytochromes.

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“…2006), cytokinin (Smets et al . 2005), ethylene (Saitou et al . 1993), red/far‐red (R/FR) light photoactivation (Saitou et al .…”

Section: Introductionmentioning

confidence: 99%

The shoot regeneration capacity of excised Arabidopsis cotyledons is established during the initial hours after injury and is modulated by a complex genetic network of light signalling

Nameth

Dinka

Chatfield

et al. 2012

Plant Cell & Environment

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Excised plant tissues (explants) can regenerate new shoot apical meristems in vitro, but regeneration rates can be inexplicably variable. Light affects rates of shoot regeneration, but the underlying mechanisms are poorly understood. Here, excised Arabidopsis cotyledons were dark-light shifted to define the timing of explant light sensitivity. Mutants and pharmacological agents were employed to uncover underlying physiological and genetic mechanisms. Unexpectedly, explants were most light sensitive during the initial hours post-excision with respect to shoot regeneration. Only~100 mmol m -2 s -1 of fluorescent light was sufficient to induce reactive oxygen species (ROS) accumulation in new explants. By 48 h post-excision, induction of ROS, or quenching of ROS by xanthophylls, increased or decreased shoot regeneration, respectively. Phytochrome A-mediated signalling suppressed light inhibition of regeneration. Early exposure to blue/UV-A wavelengths inhibited regeneration, involving photoreceptor CRY1. Downstream transcription factor HY5 mediated explant photoprotection, perhaps by promoting anthocyanin accumulation, a pigment also induced by cytokinin. Surprisingly, early light inhibition of shoot regeneration was dependent on polar auxin transport. Early exposure to ethylene stimulated dark-treated explants to regenerate, but inhibited light-treated explants. We propose that variability in longterm shoot regeneration may arise within the initial hours post-excision, from inadvertent, variable exposure of explants to light, modulated by hormones.

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Action spectrum for light-induced formation of adventitious shoots in hairy roots of horseradish

Cited by 17 publications

References 16 publications

Phytochrome-Mediated Inhibition of Coleoptile Growth in Rice: Age-dependency and Action Spectra†

Phytochrome-Mediated Inhibition of Coleoptile Growth in Rice: Age-dependency and Action Spectra†

Fluence and Wavelength Requirements for Arabidopsis CAB Gene Induction by Different Phytochromes

The shoot regeneration capacity of excised Arabidopsis cotyledons is established during the initial hours after injury and is modulated by a complex genetic network of light signalling

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