Ho, H.H., C.X. Hong & D.C. Erwin. Phytophthora inundata isolated from diseased alfalfa roots in Southern California. Mycotaxon 97: 349-358. 2006.

ABSTRACT: Phytophthora inundata was isolated from diseased alfalfa roots in Imperial County (Imperial Valley) of California. It is characterized by non-papillate, non-deciduous, internally proliferating ovoid to obpyriform sporangia, relatively large oogonia (av. 43 m) with thick-walled, aplerotic oospores, predominantly or entirely amphigynous antheridia, spherical hyphal swellings with radiating hyphae and cardinal temperatures of 5, 27-28, and 36oC. The similarity in morphology and cultural characteristics between the alfalfa isolate and P. inundata was confirmed by single-strand conformation polymorphism (SSCP) and DNA sequence analyses. This is the second world record of P. inundata found outside UK and Europe and although it is the first report of its association with diseased alfalfa roots, it was weakly pathogenic to alfalfa seedlings. The significance of this new discovery is discussed.

KEYWORDS: Oomycetes, Medicago sativa, Pythiaceous fungi, Stramenopile, root rot