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Chloroplast transcription is required to express the nuclear genes rbcS and cab. Plastid DNA copy number is regulated independently.

Abstract：

:RbcL and rbcS mRNA levels and plastid transcription activity are low in the basal meristematic region of barley primary leaves and increase coordinately during leaf cell development with a similar time course in dark-grown or illuminated seedlings. The capacity of light to cause cab mRNA accumulation shows a similar dependence on leaf cell development. These results indicate that the initial activation of chloroplast gene expression and the expression of some nuclear genes encoding plastid proteins are coupled to leaf cell development. RbcL and rbcS mRNA levels and plastid transcription activity decline in older leaf sections of dark-grown or illuminated barley. The decreases in plastid transcription and rbcS and rbcL mRNA levels in older dark-grown seedlings could be reversed by plant illumination. Therefore, while the initial activation of plastid transcription and accumulation of rbcS mRNA are largely light-independent, these events become light-dependent in older leaves of dark-grown barley. If the initial increase in plastid transcription which occurs early in leaf cell development is prevented by tagetitoxin, a specific inhibitor of the plastid RNA polymerase, rbcS mRNA does not accumulate and cab mRNA accumulation cannot be induced by light. The effect of tagetitoxin is selective because this compound does not inhibit barley leaf growth, or the normal accumulation of nuclear-encoded actin and BN3 transcripts and plastid DNA which occurs during chloroplast development. Furthermore, a barley pigment-deficient mutant, alb-f17, and plants containing photo-oxidized plastids show parallel reductions in plastid transcription activity and levels of rbcS and cab mRNA. This suggests that the activation of plastid transcription during the early stages of chloroplast biogenesis is necessary for the expression of rbcS and cab.

journal_name

Plant Mol Biol

journal_title

Plant molecular biology

authors

Rapp JC,Mullet JE

doi

10.1007/BF00037063

subject

Has Abstract

pub_date

1991-10-01 00:00:00

pages

813-23

issue

eissn

0167-4412

issn

1573-5028

journal_volume

pub_type

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Chloroplast transcription is required to express the nuclear genes rbcS and cab. Plastid DNA copy number is regulated independently.