To develop a suitable method of producing marker-free transgenic banana plants, we used an improved binary expression vector, in which the recombinase gene are, the positive selectable marker gene hpt and the counter selectable marker gene codA were placed between two directly repeated loxP sites. That cre gene was under the control of a heat shock-inducible promoter, so that the markers and cre genes can be excised simultaneously after heat shock treatment of embryos before their regeneration. The use of a heat shock promoter in an inducible cassette has the advantage that the response mechanism is evolutionary conserved, suggest ing a high probability that a heat shock promoter from one species will be properly regulated in most other plant species(Ainley and Key, 1990)