Gene Superfamily Responsible for Devastating Plant Diseases

A team of researchers from the Virginia Bioinformatics Institute and Wageningen University in the Netherlands has identified a superfamily of pathogen genes that is involved in infection of plants. More than 370 effector genes, mostly accounted by the Avh (avirulence homolog) gene superfamily, were identified from the plant pathogens Phytophthora sojae and P. ramorum. The proteins produced by these genes work in such a way as to make the plants more prone to pathogen infection.

P. sojae is responsible for an annual loss of $1–2 million in soybean yield in the US alone. P. ramorum on the other hand is the causal organism of the sudden oak death syndrome that devastated thousands of oak trees in California and Oregon. The Irish Potato Famine (the Great Hunger 1845-1852) was also caused by a member of  the genus Phytophthora.

The Avh superfamily is one of the most rapidly evolving parts of Phytophthora’s genome. Protein effectors encoded by members of the Avh gene superfamily have very different amino acid composition. All of them, however, share a common motif at the end of the protein (N-terminal) that facilitates protein entry into plant host cells. The gene family might be the key to the pathogen’s ability to outsmart plant defense systems.

The abstract of the article published by PNAS is available at http://www.pnas.org/cgi/content/abstract/0709303105v1 For more information, visit https://www.vbi.vt.edu/