Light-induced transcription of chloroplast genes. psbA transcription is differentially enhanced in illuminated barley.

R R Klein,J E Mullet

doi:10.1016/s0021-9258(19)39915-6

Abstract

Transcription and Northern dot blot analyses were used to determine the relationship between light-induced changes in RNA levels and transcription in barley and maize plastids. Overall plastid transcription activity is near maximum and largely light independent in apical sections of 4.5-day-old dark-grown barley seedings. With continued development in the dark, transcription activity in barley plastids declined precipitously, but transcription could be reactivated if plants were illuminated. Illumination of 8-day-old dark-grown barley seedlings increased the transcription of psbA, rbcL, and 16 S rDNA; however, the stimulation of psbA transcription was 2-4-fold more than rbcL or 16 S rDNA. Differential enhancement of psbA transcription occurred when 4.5- or 8-day-old dark-grown seedlings were illuminated, and the influence persisted in plants illuminated for 72 h. Illumination of 8-day-old dark-grown barley caused an increase in psbA and rbcL mRNA levels, but the increase in psbA mRNA was greater than that of rbcL. Similarly, illumination of 9-day-old dark-grown maize increased plastid transcription activity and the levels of psbA and rbcL mRNA. These results indicate that light can modulate overall plastid transcription activity and differentially stimulate the transcription of genes including psbA.

Highlights

Transcription and Northern dot blot analyses were used to determine the relationship between light-induced changes in RNA levels and transcription in barley and maize plastids
Illumination of &day-old dark-grown barley seedlings increased the transcription of psbA, t&L, and 16 S rDNA; the stimulation of psbA transcription was 2-4-fold more than rbcL or 16 S rDNA
Illumination of g-day-old dark-grown maize increased plastid transcription activity and the levels of psbA and rbcL mRNA. These results indicate that light can modulate overall plastid transcription activity and differentially stimulate the transcription of genes including psbA

Summary

Introduction

Transcription and Northern dot blot analyses were used to determine the relationship between light-induced changes in RNA levels and transcription in barley and maize plastids. Overall plastid transcription activity is near maximum and largely light independent in apical sections of 4.5-day-old dark-grown barley seedings. Illumination of &day-old dark-grown barley seedlings increased the transcription of psbA, t&L, and 16 S rDNA; the stimulation of psbA transcription was 2-4-fold more than rbcL or 16 S rDNA. Illumination of g-day-old dark-grown maize increased plastid transcription activity and the levels of psbA and rbcL mRNA. These results indicate that light can modulate overall plastid transcription activity and differentially stimulate the transcription of genes including psbA. The abundance of specific chloroplastencoded transcripts varies upon illumination, indicating control of plastid gene expression at the level of transcription, RNA processing, or transcript stability (Mullet and Klein, 1987; Klein and Mullet, 1987; Gamble et al, 1988). Pea and spinach primary leaf growth is restricted in darkness, and light induces leaf development and increases the levels of plastid DNA, RNA, and protein (Lamppa et al, 1980; Lamppa and Bendich, 1979; Scott and Possingham, 1983; Sasaki et al, 1984, 1985; Bennett et al., 1984; Herrmann et al, 1985; Deng and Gruissem, 1988)

Methods

Results

Conclusion