The botanical magazine = Shokubutsu-gaku-zasshi

, Volume 91, Issue 4, pp 255–261 | Cite as

Apparent Pfr killer reaction and P* denaturation in segments of etiolated pea epicotyl

  • Yukio Shimazaki
  • Masaki Furuya
Article
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Abstract

When totally etiolated pea epicotyls were cut into segments and incubated with potassium phosphate buffer, pH 6.0, in the dark at 25 C, an instantaneous loss of photoreversible absorbance change, Δ (ΔA) between 660 and 730 nm, was observed after the first irradiation with actinic red light in the spectrophotometric measurement of phytochromein vivo. The shorter the epicotyl segments, and the longer the period of dark incubation, the greater was the loss detected in the measurement.

A remarkable decline of Δ(ΔA) in the far-red region was seen inin vivo difference spectra for phytochrome, after the epicotyl segments were incubated in the dark at 25 C. As the period of dark incubation was prolonged, the ratio of the maximal change of Δ(ΔA) in the far-red region to that in the red region was reduced. It decreased to ca. one third of the initial value after incubation for 8 hr.

The evidence indicates that Pfr killer activity and P* denaturation, both of which have so far been known onlyin vitro, can also occur in segments of etiolated pea epicotyls.

Keywords

Potassium Phosphate Buffer Rapid Loss Dark Incubation Apical Hook Epicotyl Segment 

Abbreviations

Pr

red light absorbing form of phytochrome

Pfr

far-red light absorbing form of phytochrome

P*

denaturation, protein denaturation of phytochrome resulting in decrease of Δ Afr/Δ Ar

F1

the first actinic far-red light

F2

the second actinic far-red light

R1

the first actinic red light

S1

a 4 mm-long stem region cut from 1 mm below the apcial hook of an etiolated pea epicotyl, equivalent to the S1 of Purves and Hillman (1958) except that the latter was 5 mm long

pCMB

p-mercuribezonate

mg fr wt

mg fresh weight

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Copyright information

© The Botanical Society of Japan 1978

Authors and Affiliations

  • Yukio Shimazaki
    • 1
  • Masaki Furuya
    • 1
  1. 1.Department of Botany, Faculty of ScienceUniversity of TokyoTokyo

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