They hope it will remove the need for chemical dyes, which can be harmful to the environment.
Scientists also aim to create a stretchy, wrinkle-free cotton to replace synthetic fabrics.
They contain plant tissue, which within days will grow into cotton plants: not standard, everyday white cotton, but ones with a dazzling array of colours.
Colleen MacMillan leads the team of scientists who have cracked cotton's molecular colour code, adding genes to make the plants produce a colour.
"We've seen some really beautiful bright yellows, sort of golden-orangey colours, through to some really deep purple," fellow scientist Filomena Pettolino said.
Another positive sign is that coloured cotton genes, inserted into green tobacco plants, have shown up as coloured splotches on the leaves.
If the leaves of the biotech (genetically modified) cotton are coloured, the all-important fibre will be as well. »
