Nucleotide depletion and chloroplast division.

We have described the identification of crinkled leaves 8 (cls8) which contains a mutation within the gene encoding the large subunit of ribonucleotide reductase (RNR), the enzyme that catalyses the rate limiting step in the synthesis of deoxyribonucleotide triphosphates (dNTPs) for DNA synthesis and repair. The mutation resulted in plants with altered leaf and flower morphology, reduced root growth, bleached leaf sectors and reduced levels of dNTPs. An interesting consequence of the mutation was its effect on chloroplast division. Mutant plants had fewer, larger chloroplasts and a reduced number of chloroplast genomes compared to wild type plants. The morphological phenotype may be a consequence of altered chloroplast replication.