Thursday, June 25, 2015

Ug-99, the story that disappeared

Ug-99 (aka, Race TTKSK) is a strain of wheat rust (Puccinia graminis f. sp. tritici) that was first identified in Uganda in 1999.  It demonstrated the ability to overcome the most common sources of genetic resistance to wheat rust that have been bred into modern, high yielding strains of wheat.

The spoors of this disease are spread, primarily, by wind.  It spread rapidly.

Image from FAO, Food and Agriculture Organization of the UN.
Africa is not a huge producer of wheat.  However, Pakistan and India are.  Together, they produce...and eighth of the wheat produced in the world.

Like all commodities, wheat is priced 'at the margin'.  That is, commodities are priced based on the transaction price of  the last unit sold. A shortage of a commodity with no viable substitutes entails impoverishment of the marginal bidder and extinction of all sub-marginal bidders.  That is an oblique way of saying that a war will start.

One must wonder if the arrival of Ug-99 in Iraq and Syria amplified existing geopolitical tensions and energized the ascendancy of radical groups in the region.

Defense in Depth

Military people often discuss a concept called Defense in Depth.  Distance is time.  Time is the ability to respond.  Plant breeders think the same way.

We were lucky, this time.  The disease originated in BF Uganda.  That bought the world 15 years to respond.  Several lines that show economically significant resistance to Ug-99 have been identified.  There has been time to build up seed stocks prior to the arival of Ug-99's arrival in the Indus valley.

This story would have played out differently if the mutation first shown up in the Indus valley, the Ukraine, Argentina, Northern China, France or South Dakota.  We were lucky.  There was time to respond.


Classical music compositions often have a period of relatively peaceful music between more intense scores.  It is often an interlude used by the composer to redirect the theme.

Ug-99 continues to mutate.  It continues to evolve around genetics that were used to buttress primary sources of wheat rust resistance.  It is slowly chewing its way east.  Wheat fields are few and far between.  Mean distance between hosts is not favorable to rapid spread.

We have yet to see how this theme develops.  The Great Composer is not done.

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