A plasmid or circular genome

You have a plasmid, or another sequence with no ends, and its annotation as GFF3, as an annotation tool such as Bakta or Prokka writes it.

karyon pEX1 --circular pEX1.gff3 -o plasmid.svg

The place is the sequence, by its name, and --circular draws it round: position zero at twelve o'clock, running clockwise, inside a ruler. A circle closes where its sequence ends, which the annotation's ##sequence-region line says here; a FASTA of the sequence among the files says it too. Each gene is an arc ending in a point at its 3' end, on the outer half of the ring for the forward strand and the inner half for the reverse, so the divergent pair tetR and tetA point away from each other. What the annotation calls something other than a gene, here the origins of replication and of transfer, is an arc with no point in a muted ink, keyed by what the annotation calls it. The ring is named for what it holds, and the key under the circle says what each colour means.

Change it

To	Write
Add the sequence's GC skew as a second ring, which turns over at the origin of replication	pEX1.fa after pEX1.gff3
One colour for every gene	pEX1.gff3 --color '#6a3d9a'
Name the ring yourself	pEX1.gff3 --label annotation
Leave the names off	pEX1.gff3 --no-names
Leave out the key	--no-legend
Another title in the middle	--title 'pEX1, a plasmid'
Draw it along a line, the genes as arrows	leave out --circular
Draw one stretch of it along a line	pEX1:3,000-5,500 pEX1.gff3, with no --circular

Calls and depth over the plasmid are rings of their own in the same way, in the order written, the first outermost; a whole sequence draws a chromosome round with both.

The example files: pEX1.gff3 and pEX1.fa. Every option: karyon help features, or the command line reference.