The Cause Behind the Great Potato Famine (And Why it's Coming Back)

Saturday, December 26, 2009 by: David Gutierrez, staff writer
Tags: potato famine, crop failure, health news

(NaturalNews) Researchers have sequenced the genome of the fungus responsible for the Great Irish Potato Famine in the 1800s, uncovering the reason that the organism continues to plague potato farmers to this day.

"This pathogen has an exquisite ability to adapt and change, and that's what makes it so dangerous," said lead researcher Chad Nusbaum of the Broad Institute in Cambridge, Mass.

The organism, known as Phytophthora infestans, is a type of water mold that continues to cost potato farmers billions of dollars every year. It prefers cool, wet climates and is capable of destroying entire fields of potatoes and tomatoes within only a few days. In 2003, P. infestans destroyed Papua New Guinea's entire potato crop.

The mold evolves resistance to antifungal sprays with astonishing speed. In just the last few years, potato farmers in the United Kingdom have increased chemical spraying by 30 percent in an attempt to hold the organism at bay, and the ongoing blight in Ireland has been called "the worst in living memory," according to the BBC.

According to information published in the journal Nature, P. infestans' genome is especially large, at least twice as long as the genetic code of its closest relatives. Some regions of the genome are particularly dense, containing many genes in a small area, while others are much less dense. It is these gene-light areas that may hold the key to the organism's adaptability: more than 700 key genes were mapped in these regions, some of them coding for attacks on potatoes' immune systems.

"The regions change rapidly over time, acting as a kind of incubator to enable the rapid birth and death of genes that are key to plant infection," said co-lead author Brian Haas. "As a result, these critical genes may be gained and lost so rapidly that the hosts simply can't keep up."

Modern agriculture has exacerbated the problem, said Paul Birch of the Scottish Crop Research Institute. Widespread application of chemicals encourages pest evolution, while genetic standardization of food crops makes them more vulnerable to infestation.

Sources for this story include: news.bbc.co.uk.