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Potatoes are subject to attack from a number of pathogens including the Colorado Potato Beetle, mites, the potato tuber moth, and the potato root nematode. The most notorious potato bug is
Phytophthora infestans, also known as late blight. It was the cause of the potato blight famine in Ireland in the 1840s which led to an estimated 1 million people dying of starvation. The potato bug is still a problem for farmers in Europe and the United States.
What makes the pathogen such a tricky customer is its powerful ability to adapt and change, enabling it to evade and survive the control systems that have been designed over the years.
By lying the potato bug's genome bare scientists discovered that most of it consisted of repetitive sequences which were once dismissed as junk DNA. Yet it's these genes which enable the pathogen to gain a foothold and takeover potato physiology. There is a massive gene turnover here, with DNA regions changing rapidly over time, which is probably what allows the pathogen to resist pesticide attack.
However, an understanding of the molecular basis of its destructive power should help scientists to develop better ways of spotting outbreaks and responding to them with more powerful and smarter pesticides.
