Downy mildew of pea caused by

Answer: Option A

Downy mildew of pea caused by Perenospora pisi.
Downy mildew of peas is caused by the obligate parasite Peronospora pisi, which occurs sporadically throughout temperate pea-growing regions across the world.
To screen pea lines against this biotrophic pathogen, a suitable and reproducible in vitro method using living plant material is required.