Hyaloperonospora arabidopsidis
Hyaloperonospora arabidopsidis is a species from the family Peronosporaceae. It is an obligate parasite and the causal agent of the downy mildew of the plant model organism "Arabidopsis thaliana". While "H. arabidopsidis" has for a long time been subsumed under "Peronospora parasitica" (now "Hyaloperonospora parasitica"), recent studies have shown that "H. parasitica" is restricted to "Capsella bursa-pastoris" as a host plant. Like the other "Hyaloperonospora" species, "H. arabidopsidis" is highly specialized to "Arabidopsis thaliana".