The invention relates to methods and compositions for genetic transformation of both juvenile and mature citrus. In some embodiments, the invention provides methods and compositions for genetic transformation of citrus using Rhizobia-mediated DNA delivery, and also methods of enhancing the frequency of genetic transformation of mature citrus by any DNA transfer method, including Sinorhizobium. Internodal stem sections prepared from epicotyls of citrus seedlings or freshly emerging shoots of mature citrus plants (e.g., first shoots from buds of mature plants following grafting onto rootstock or very young shoots of mature plants) are preconditioned for transformation by inducing callus formation on an artificial medium. All callus and any developing meristematic regions in immediately adjacent tissue are substantially or completely removed and the preconditioned explants are then transformed by Sinorhizobium or other known methods. Whole plants or shoots to be grafted onto rootstocks are subsequently regenerated from the transformed cells.
