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Phytophthora infestans Produces Oospores in Fruits and Seeds of Tomato

November 2001 , Volume 91 , Number  11
Pages  1,074 - 1,080

Evgenia Rubin , Alexander Baider , and Yigal Cohen

Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel

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Accepted 23 July 2001.

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. Oospores were also formed on the surface of fruits kept in moisture-saturated atmosphere. 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 oospores, thus making them a threatening source of blight inoculum. Such fruits may also release airborne oosporic inoculum that may introduce recombinant genotypes within a growing season. Although Phytophthora infestans is seedborne in tomato, to our knowledge, this is the first report on the occurrence of oospores in tomato seeds. Whether such tomato seeds produce blighted seedlings remains to be shown.

Additional keywords: airborne oospores , epidemiology , potato , seedborne oospores , sexual recombination , sporulation .

© 2001 The American Phytopathological Society