Mechanical wounding through tapping has long been known to induce laticifer differentiation in Hevea brasiliensis. Recent studies reveal that dehydration, hydrogen peroxide, and jasmonates can similarly play a role in wound-induced laticifer differentiation. The Hevea ethylene response factor gene, HbERF-IXc5, is thought to be an ortholog to ERF1 of Arabidopsis. ERF1 has been suggested as a component of defence responses through the involvement of the ethylene and jasmonic acid signalling pathways. In this study, Agrobacterium tumefaciens-mediated genetic transformation was carried out with this candidate gene. A histological analysis of HbERF-IXc5 lines revealed several changes in anatomy, particularly in terms of the number of laticifer cells. The results suggest that HbERF-IXc5 is a transcription factor driving the expression of some target genes involved in jasmonate-induced laticifer differentiation.