Elicitins, holoproteins which act as inducers of hypersensitivity
tobacco, were considered as a characteristic of Phytophthora.
are also produced, along with glycosylated isoforms, by three species
belonging to the related genus Pythium, Py. vexans, Py.
oedochilum and Py. marsipium, while other Pythium
do not possess such proteins. Various elicitin-like sequences were
determined, bringing novel features to the elicitin family, such as an
histidine residue and C-terminal extensions on the deduced
peptide sequences. As the unique elicitin content of these species supports
distinct location among Pythiaceae, we suggest the
separation of vexans, Py. oedochilum and Py. marsipium
from Pythium and consider them as linking species between
Phytophthora and Pythium.