UNIQUE CHLOROPLAST GENOME IN <i>SPIROGYRA MAXIMA</i> (CHLOROPHYTA) REVEALED BY PHYSICAL AND GENE MAPPING¹

Abstract

ABSTRACT The choroplast genome in Spirogyra maxima (Hassall) Kützing is 130 kb in size and locks large repeat units. The 16S and 23S rRNA genes are separated by approximately 44 kb, which makes co‐transcription of these genes unlikely. Spirogyra maxima is unusual among green algae in that its chloroplast genome apparently does not contain the tuf A gene, the absence of which is characteristic of land plant chloroplast DNAs. Apart from three groups of genes, pas A ‐psa B, psb C ‐psb D, and atp A ‐atp F/H, which are co‐transcribed in land plants and also map together in S. maxima chloroplast DNA, the S. maxima gene order overall is unlike that of any other chloroplast genome.