There are four genes, rmlB (dTDP-glucose 4, 6-dehydratase), rmlD (dTDP-4-dehydrorhamnose reductase), rmlA (glucose-1-phosphate thymidylyltransferase), and rmlC (dTDP-4-dehydrorhamnose 3,5-epimerase) that are involved in the biosynthesis of dTDP-L-rhamnose.
Source: wiktionary