The structure of chloroplast DNA molecules and the effects of light on the amount of chloroplast DNA during development in Medicago truncatula.

We used pulsed-field gel electrophoresis and restriction fragment mapping to analyze the structure of Medicago truncatula chloroplast DNA (cpDNA). We find most cpDNA in genome-sized linear molecules, head-to-tail genomic concatemers, and complex branched forms with ends at defined sites rather than at random sites as expected from broken circles. Our data suggest that cpDNA replication is initiated predominantly on linear DNA molecules with one of five possible ends serving as putative origins of replication.

Changes in chloroplast DNA during development in tobacco, Medicago truncatula, pea, and maize.

We examined the DNA from chloroplasts obtained from young and fully expanded leaves of tobacco (Nicotiana tabacum L.), Medicago truncatula, pea (Pisum sativum L.), and maize (Zea mays L.