In this reporting period, we confirmed that overexpression of the P19and H2A gene or repression of the AGO2 and NRPD1 genes could improve Agrobacterium-mediated transformation / gene expression in juvenile citrus tissues but the increases were no higher than 3-fold. We had been trying to repeat the experiments to determine their effects on the mature citrus tissues but due to limited mature plant tissues in winter months, we have not yet produced any meaningful results. However, we did observe that the use of an antimicrobial and an anti-oxidation compound worked reasonably well to reduce contamination and tissue browning problems. We started in planta regeneration of juvenile tissues under non-sterile conditions. We observed that young shoots could be developed from decapitated hypocotyls at a reasonably high efficiency. The shoots produced were not derived from any preexisting meristem tissues because all meristem cells were completely removed. We also tested and confirmed the effects of several chemical regulators on both transient expression and stable transformation efficiencies.