Lettuce: Any of the various plants of the genus Lactuca, especially L. sativa, cultivated for its edible leaves. (From American Heritage Dictionary, 2d ed)Crinivirus: A genus of plant viruses in the family CLOSTEROVIRIDAE. Transmission is by whiteflies. Lettuce infectious yellows virus is the type species.Agricultural Irrigation: The routing of water to open or closed areas where it is used for agricultural purposes.Vaccines, Edible: Vaccines or candidate vaccines derived from edible plants. Transgenic plants (PLANTS, TRANSGENIC) are used as recombinant protein production systems and the edible plant tissue functions as an oral vaccine.