Given the task definition and input, reply with output. In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.

Duckweeds are small, floating aquatic plants with a number of useful characteristics, including edibility, fastgrowing, and a clonal proliferation. Duckweed is also fed to animals as a diet complement because of its high nutritional value. Porcine epidemic diarrhea virus (PEDV) is a major causative agent of fatal diarrhea in piglets and is a serious problem in the hog-raising industry. In this study, we assessed the feasibility of producing a protective antigen for the PEDV spike protein 1 using duckweed, Lemna minor. Stably transformed Lemna were obtained by co-cultivation with A. tumefaciens EHA105 harboring the PEDV spike protein gene. Transgene integration and expression of the PEDV spike protein 1 gene were confirmed by genomic PCR and RT-PCR and western blot analysis of transgenic Lemna, respectively. This is the first report of the expression of a vaccine antigen against an animal infectious disease in duckweed. Additional key words: aquatic plant, porcine diarrhea, spike protein, transformation, vaccine Hort. Environ. Biotechnol. 52(5):511-515. 2011.
Expression of the Protective Antigen for PEDV in Transgenic Duckweed, Lemna minor