Author: Jeremy Cherfas

We generally adopt the view that diversity is a good thing. But there are cases where it definitely is not. One such is being discussed over at Small Things Considered, “the microbe blog”. In part one, Elio Schaechter answers Five Questions about Oomycetes. Number one: What makes oomycetes important to people? Answer, potato blight, and many other diseases.

Lots of good stuff, but we’re particularly taken with his colleague Merry Youle’s addition on Oomycete mating types and the potato blight. The point is, late blight is now capable of sex outside its home in Mexico, and has been since the late 1970s. Two consequences follow. First, the spores of sexual reproduction are capable of surviving over winter; currently, cold winters destroy the asexual spores giving potato growers a fighting chance of avoiding the blight. Over-wintering spores could be a disaster. Secondly, and perhaps more important in the long term, sexual recombination will allow late blight to do its own gene shuffling, and could come up with new combinations of genetic diversity that could make it even more virulent. Fungicide resistance in over-wintering spores would be quite a threat. Youle concludes:

K. V. Raman, a professor of plant breeding at Cornell University and an authority on potatoes in Mexico and Eastern Europe, observes: The conditions prevalent in today’s Russia are all too reminiscent of those of Ireland in the mid-19th century. That was the time of the Great Famine in Ireland (the subject of our next post). As was the case then in Ireland, Russia today has a population dependent on the potato and an aggressive blight out of control. In this, Russia is not alone. This time, the impacts are expected to be global.

Scary, or what? I’m looking forward to two more posts promised on the subject.