Phytophthora infestans produces oospores in fruits and seeds of tomato

Tomato fruits at the mature green stage coinoculated with A1 + A2 sporangia of Phytophthora infestans, the late blight causal fungus, showed abundant oospores in the vascular tissues, pericarp, columella, and placenta. Oospor es were also! formed on the surface of fruits kept in moisture-saturated at mosphere. Occasionally, oospores were enclosed between the epidermal hairs of the seed coat. In a few seeds, oospores were detected inside the embryo. The data suggest that blighted tomato fruits may carry a large number of o ospores, thus making them a threatening source of blight inoculum. Such fru its may also release airborne oosporic inoculum that may introduce recombin ant genotypes within a growing season. Although Phytophthora infestans is s eedborne in tomato, to our knowledge, this is the first report on the occur rence of oospores in tomato seeds. Whether such tomato seeds produce blight ed seedlings remains to be shown.