The objective of this work was to produce 'Valencia' sweet orange transgenic plants with the cecropin MB39 gene controlled by a phenylalanine ammonia-lyase gene promoter from citrus in order to direct gene expression in xylem vessels. The genetic transformation was mediated by Agrobacterium tumefaciens with the co-culture of epicotyl segments. Eleven transgenic plants were selected by PCR with the amplification of a 189 bp fragment, which were acclimatized to greenhouse. The integration of the transgene was confirmed in three plants by Southern blot analysis.