Kinetic Studies on Pigment Systems Concerned with the Photoperiodic Response in <i>Pharbitis nil</i>

Takimoto, Atsushi; Hamner, K. C.

doi:10.1104/pp.40.5.865

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…Not only do seedlings of Pharhiii.s nil show circadian rhythmicity in the capacity to flower in response to the titnitig of a second red light pulse given after a first satutating exposute to ted (Eig, 1), but there are also parallel changes in the photon irradiance for half maximal response to the second pulse (Figs 2, 3 and Table 1), Evidence suggestive of a rhythmic change in photoresponsiveness for flowering was presented earlier by Hatnner (1965a), andEriend, (1975). Takimoto & Hamner (1965c) also found evidence of a 10-fold reduction in the saturating irradiance over the early hours of darkness following continuous white fluorescent light. We can now add that the exposure for half maxitnal photoconversion of phytochrome also changes when measured spectrophotometrically in the photoperiodically sensitive cotyledons (Fig, 5).…”

Section: Discussionmentioning

confidence: 78%

Photoperiodism and rhythmic response to light

King

Schäfer

Thomas³

et al. 1982

Plant Cell & Environment

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Abstract. Seedlings of Pharhitis nil show a circadian rhythm in the capacity to flower in response to the timing of a second red light pulse given at various times after a first saturating exposure to red when this is given together with a benzyladeninc spray. There are also changes in the photon irradiance required for half maximum response to the second red pulse. The photochemical properties of phytochrome in the photoperiodically sensitive cotyledons were also shown to change rhythmically. Oscillations in both pr→ Pfr and Pfr→ Pr photoconversion characteristics persisted over at least two circadian cycles with a periodicity of about 12 h. There were, however, no significant oscillations in either Pfr peak absorbance or in Δ(ΔA). The changes in sensitivity for the photoconversion of Pr→ Pfr did not parallel the much larger changes in sensitivity of the flowering response to red light. The amplitude of the Pr→ Pfr rhythm was at least as great as that for Pr→ Pfr, but the flowering response to far‐red light was not rhythmic, nor was there any large change in sensitivity. The changes in photoconversion properties may reflect a basic biochemical oscillation which affects both photoreceptor properties and sensitivity to photoreceptor input. There was also a marked rhythm in the Pfr/P ratio that would be established by a saturating pulse of red light and this too may have affected the flowering response to such a pulse. Far‐red light inhibited flowering when given at any time during the inductive night. After 14 h in darkness, Pfr could still be measured in the cotyledons and it was concluded that far‐red light inhibited flowering by removing Pfr As red light also inhibited flowering at this time, there may be two pools of phytochrome with different kinetic properties.

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Section: Discussionmentioning

confidence: 78%

Photoperiodism and rhythmic response to light

King

Schäfer

Thomas³

et al. 1982

Plant Cell & Environment

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“…Although inhibition by far-red light has been attributed to a number of factors, 1 factor in common in most instances is the involvement of a relatively long dark period. Some investigators have explained the inhibition of flowering of short-day plants and the dual response to far-red light as due to the action of far-red light on phytochrome (6,12,16) while others have proposed that a second pigment is also involved (9,13,20). There is instufficient information to decide if either theory is correct.…”

mentioning

confidence: 92%

“…However, far-red light has ibeen shown to inhibit flowering in a number of short-day plants including Xanthiiuni pensylvanictum (1,10), Glycine mttax (3,18), Chenopodiumii rubrumi-(5, 6), Lemiina perpusilla (17), Chrysanthentiuni sp. (4), Kalanchoe blossfeldiana (8,11), and most extensively Pharbitis nil ( 15, 16,19,20).…”

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confidence: 99%

Control of Flowering of Xanthium pensylvanicum by Red and Far-red Light

1967

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Approximately the same energy of red light was required to overcome the inhibitory effect of far-red at the second hour of darkness as was required to produce maximum red light inhibition at the eighth hour. Although far-red light was most inhibitory when given early in a long dark period, approximately the same energy of far-red light was required to saturate the far-red response at the fourth, eighth and sixteenth hours.The results are discussed in relation to other reports of far-red inhibition of flowering in short-day plants.It seems clear that the pigment phytochrome is involved somehow in the photoperiodic response.

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Photomorphogenesis and Flowering

Vince‐Prue¹

1983

Photomorphogenesis

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Kinetic Studies on Pigment Systems Concerned with the Photoperiodic Response in Pharbitis nil

Cited by 7 publications

References 10 publications

Photoperiodism and rhythmic response to light

Photoperiodism and rhythmic response to light

Control of Flowering of Xanthium pensylvanicum by Red and Far-red Light

Photomorphogenesis and Flowering

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