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The American pokeweed plant (Phytolacca americana) is resistant to several biotic and abiotic stressors. Investigation of the genes involved in defense would be aided by transient or stable over/under expression in pokeweed; however, there are no established protocols for generating transgenic pokeweed plants. Pokeweed is infected by pokeweed mosaic virus (PkMV), a potyvirus with recent genome sequence of some isolates. In this work, the complete coding sequence of the Arkansas isolate was determined and the first infectious clone of PkMV constructed. Agro-infiltration of the clone into pokeweed leaves produced the typical chlorotic mottling and systemic movement through the plant, indicative of infection by PkMV. Viral particles of purified preparations, isolated from plants inoculated with the infectious clone, were morphologically identical to PkMV, and presence of viral RNA and proteins were verified by RT-PCR and immunoblot assay. The clone-generated virus particles were successfully transmitted by aphids to healthy pokeweed plants. Agro-infiltration of the infectious clone encoding the open reading frame of enhanced green fluorescent protein (eGFP) resulted in systemic expression of eGFP and supports the introduction of foreign genes in pokeweed. Construction of an infectious clone of PkMV facilitates creation of a viral vector to manipulate expression of pokeweed genes involved in defense and to better understand how pokeweed resists pathogens and abiotic stress. [ABSTRACT FROM AUTHOR]