Planta

, Volume 168, Issue 4, pp 482–492

Expression of nuclear genes as affected by treatments acting on the plastids

  • R. Oelmüller
  • I. Levitan
  • R. Bergfeld
  • V. K. Rajasekhar
  • H. Mohr
Article

DOI: 10.1007/BF00392267

Cite this article as:
Oelmüller, R., Levitan, I., Bergfeld, R. et al. Planta (1986) 168: 482. doi:10.1007/BF00392267

Abstract

In a preceding paper (Oelmüller and Mohr 1986, Planta 167, 106–113) it was shown that in the cotyledons of the mustard (Sinapis alba L.) seedling the integrity of the plastid is a necessary prerequisite for phytochrome-controlled appearance of translatable mRNA for the nuclear-encoded small subunit (SSU) of ribulose-1,5-bisphosphate carboxylase and the light-harvesting chlorophyll a/b-binding protein of photosystem II (LHCP). It was concluded that a signal from the plastid is essential for the expression of nuclear genes involved in plastidogenesis. The present study was undertaken to characterize this postulated signal. Chloramphenicol, an inhibitor of intraplastidic protein synthesis and Norflurazon, an inhibitor of carotenoid synthesis (to bring about photooxidative sensitivity of the plastids) were applied. We obtained the following major results. (i) After a brief period of photooxidative damage a rapid decrease of the above translatable mRNAs was observed. Conclusion: the signal is short-lived and thus required continually. (ii) Once the plastids became damaged by photooxidation, no recovery with regard to nuclear gene expression was observed after a transfer to non-damaging light conditions. Conclusion: even a brief period of damage suffices to prevent production of the signal. (iii) Chloramphenicol inhibited nuclear gene expression (SSU, LHCP) and plastidic development when applied during the early stages of plastidogenesis. Once a certain stage had been reached (between 36–48 h after sowing at 25° C) nuclear gene expression became remarkably insensitive toward inhibition of intraplastidic translation. Conclusion: a certain developmental stage of the plastid must be reached before the signal is released by the plastid. (iv) Under the growth conditions we adopted in our experiments the plastids in the mesophyll cells of mustard cotyledons developed essentially between 36 and 120 (-144) h after sowing. Only during this period could translatable mRNAs for SSU and LHCP be detected. Conclusion: the signal is released by the plastids only during this time span.

Key words

Nuclear gene expressionPhotooxidation of chloroplastPhytochromeSinapis

Abbreviations

CAP

Chloramphenicol (D-threo)

cFR

continuous far-red light

FR

far-red light (3.5 W·m-2)

GPD

glyceraldehyde-3-phosphate dehydrogenase

LHCP

light-harvesting chlorophyll a/b-binding protein of photosystem II

LSU

large subunit of RuBPCase

MDH

malate dehydrogenase

NF

Norflurazon

NIR

nitrite reductase

Pfr

physiologically active form of phytochrome

R

red light (6.8 W·m-2)

RG9-light

long-wavelength far-red light (10 W·m-2)

RuBPCase

ribulose-1,5-bisphosphate carboxylase

SSU

small subunit of RuBPCase

WLs

strong white light (28 W·m-2)

\(\varphi _\lambda = \frac{{[Pfr]\lambda }}{{[Ptot]}}\)

photoequilibrium of phytochrome at wavelength λ

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • R. Oelmüller
    • 1
  • I. Levitan
    • 1
  • R. Bergfeld
    • 1
  • V. K. Rajasekhar
    • 1
  • H. Mohr
    • 1
  1. 1.Biologisches Institut II der UniversitätFreiburgFederal Republic of Germany