Influence of plastids on transcription of nuclear
and mitochondrial genes
Börner, T., Churin, Y., Hedtke, B., Hess, W.R.
Institut für Biologie, Humboldt-Universität, Chausseestr. 117, D-10115 Berlin, Germany
The albostrians mutant of barley (Hordeum vulgare) has been investigated to reveal regulatory interactions between the DNA-containing organelles of the plant cell. This mutant produces entirely white and green leaves. Both types of leaves have the same nuclear genotype, but differ from each other with respect to the degree of plastid differentiation: cells of green leaves contain normally developed chloroplasts whereas cells of white leaves possess small plastids lacking ribosomes and thylakoids. Therefore, differences in gene expression between green and white leaves should indicate an influence (possibly by a regulatory signal) of the plastid. We observed a drastically reduced transcription of nuclear genes in photosynthesis, Calvin cycle and glycolate pathway in white compared to green leaves. In contrast, transcripts of nuclear genes involved in the response against certain abiotic and biotic stress factors were found to accumulate to much higher levels in white than in green leaves. Thus, the developmental state of the plastid may control the transcription of a surprisingly large number of nuclear genes. Also the transcription of two genes encoding putative transcription factors of the Lhcb1 gene were observed to differ between green and white leaves. White leaves revealed a distinctly higher transcript level of all studied mitochondrial genes than green leaves. Interestingly, also the amount of mitochondrial DNA (related to total DNA) was higher in white vs. green leaves. Thus, the state of plastid differentiation may have an impact on mitochondrial DNA replication. The enhanced mitochondrial transcript levels in white leaves may be a secondary effect of the increase in the number of gene copies.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Monday, April 6 |
02:00 pm |