The chloroplast genome structure of the vascular plant Isoetes is similar to that of the liverwort Marchantia

Restriction site mapping was used to characterize the chloroplast genome of the lycophyte, Isoetes melanopoda. The Isoetes chloroplast genome is appro ximately 139-145 kb in size with an inverted repeat of 12-13 kb. The gene c ontent and consensus gene order are similar to that of Marchantia. A distin ctive feature of the Isoetes genome is an increased size of the small singl e copy (SSC) region possibly due to the insertion of a piece of DNA (3-8 kb ) of unknown composition. The inferred insertion, along with a slightly lar ger inverted repeat, are responsible for the apparent size difference in th e total genome relative to Marchantia. Patterns of restriction fragments we re also consistent with the presence of a small inversion (2-3 kb) in the l arge single copy (LSC) region.