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Breaking genetics

Research sponsored by Agriculture and Agri-Food Canada (AAFC) has discovered that a common pathogen of soybeans, soybean root rot (Phytophthora sojae), breaks the genetic trend known as Mendel's Law of Inheritance.

Dr. Mark Gijzen is AAFC Research Scientist and a member of the international team investigating this disease that discovered this unusual discovery. The team ascertained that P. sojae can defeat plant resistance and adapt to survive through a method known as transgenerational gene silencing.

“The genes that determine virulence are actually passed on in a Mendelian way, but the trait that they determine (virulence) is not. This is because the gene expression is changed, and this change is heritable and independent from the gene itself, or from any other genes for that matter,” he said. “So there is some other self-propagating factor, besides the genes, that is determining this trait. We think this other factor could be small RNA molecules.”

This research can provide big implications for how such diseases are studied and how virulence in this pathogen, and others like it, evolved. This could leads to new opportunities for better control and management of diseases that affect important crops, like soybeans in Canada. “An immediate application this discovery enables is that more precise diagnostic methods can now be devised to test for particular strains of the pathogen,” added Gijzen.

The next step is investigating this is continue to study the genetics of the pathogen more closely, since there are still many unanswered questions. More genetic experiments involving crossing different strains of the pathogen must be completed in order to obtain a clearer picture of this unique method of inheritance.

The research paper highlighting this discovery recently appeared in the scientific journal Nature Communications, which can be viewed here. <http://dx.doi.org/10.1038/ncomms2354>.

February 1, 2013  By David Manly