Phytophthora Sojae

Phytophthora sojae is an oomycete and a soil-borne plant pathogen that causes stem and root rot of soybean. This is a prevalent disease in most soybean growing regions, and a major cause of crop loss. In wet conditions the pathogen produces zoospores that move in water and are attracted to soybean roots. Zoospores can attach to roots, germinate and infect the plant tissues. Diseased roots develop lesions that may spread up the stem and eventually kill the entire plant. Phytophthora sojae also produces oospores that can remain dormant in the soil over the winter, or longer, and germinate when conditions are favourable. Oospores may also be spread by animals or machinery.

Phytophthora sojae is a diploid organism with a genome size of 95 Mbp (Millions of base pairs).

Natural chemical farinomalein (a metabolite from entomopathogenic fungus Paecilomyces farinosus) has shown potent and selective inhibition (0.15-5 μg/disk) against eight isolates of plant pathogenic Phytophthora sojae. These results suggest that farinomalein might be useful as a candidate pesticide for the treatment of Phytophthora stem rot in soybean.

Phytophthora sojae is also very similar to Phytophthora megasperma in many ways that they’re often mistaken for each other. In the early years of research, Phytophthora sojae and Phytophthora medicaginis were respectively known as Phytophthora megasperma f. sp. glycines and Phytophthora megasperma f. sp. medicaginis. Recent discoveries about their molecular structure, however, proved that they were indeed unambiguous species.