Researcher Les Szabo on wheat rust, GMOs

Les Szabo
Les Szabo is a research geneticist and acting research leader at the USDA-ARS Cereal Disease Laboratory on the University of Minnesota's St. Paul campus.
MPR Photo/Tom Weber

On The Daily Circuit Monday, we're talking about labeling genetically modified food. Recently, we spoke with Les Szabo, research geneticist and acting research leader at the USDA-ARS Cereal Disease Laboratory on The University of Minnesota St. Paul campus.

At the lab, scientists study rust on cereal plants like wheat, rye and barley. Wheat rust is very common and it's completely manageable because most of the wheat that's planted in the world has resistance against these kinds of rust. There are even documented cases of rust back to the Roman days, Szabo said.

When a type of rust pops up that the wheat's resistance can't handle, that's when you have the chance for an epidemic, he said. The last time that happened on a large scale was back in the '50s and '60s when Minnesotan Norman Borlaug helped breed new wheat varieties that were resistant to that kind of rust that was causing problems back then.

Since that time, Borlaug's wheats have done a good job of managing rust and resisting it. However, Szabo said there's a new problem on the horizon. Back in the late 90s in Uganda, scientists discovered a strain of stem rust that current wheats' resistances are not able to fight. That rust is called Ug99 and Szabo said 80 to 90 percent of the wheat in the world does not have resistance to this version of rust and its descendents.


Les Szabo: And so if we had a big world epidemic, we would lose 80 to 90 percent of the wheat. The odds of that happening are very slim. Rust is a very periodic disease and we do see epidemics, but they tend to be localized and they're periodic. And so, in theory, 80 percent of the wheat crop is susceptible, but in reality the odds of that happening is very slim.

Tom Weber: I've definitely heard statements of 'in a generation or two, this could be a world where no one will be able to eat any food made of wheat. Is that overhyped? Or could that really happen?

Spores of wheat rust
Spores of rust grow on wheat inside a greenhouse at the USDA-ARS Cereal Disease Laboratory on the St. Paul campus of the University of Minnesota.
MPR Photo/Tom Weber

LS: As a scientist, one is always optimist. And I think the track record is very good. If you look at what Norman Borlaug did 60 years ago, he, in a breeding program, was very successful in developing resistant varieties that lasted a long time. And there's really good progress now being made in developing new varieties with resistance to Ug99 and its relatives. And so I'm very optimistic that in a short time, resistant varieties will be developed and this particular race of wheat stem rust pathogen can be controlled, as it has in the past.

TW: Does that just reset the clock? Do we expect this to be cyclical, and we'll deal with this again in 50 years?

LS: Well, I think that's the biggest concern; that we don't learn from history. We get it solved and, like a lot of thing in sciences, whatever is the biggest problem today gets the funding, gets the focus, and over time, stem rust will be forgotten and it will chug along behind - and that will come back to bite us. So I hope we as a scientific community learn our lesson this time and that we continue to work on stem rust and developing new varieties for wheat. The bottom line is one can't get complacent and one must remember one of Norman Borlaug's famous quotes: 'Rust never sleeps.'

I'm totally confident that science will prevail and that this particular problem of Ug99 is solved. What I worry about is the next Ug99.

TW: So as you develop that next generation of wheat to beat this Ug99, to what extent might you use GMOs to develop the next generation of wheat?

LS: If you use a liberal stance and say 'genetic enhancement' is genetic modification, then genetic enhancement has been going on as long as man has selected one kind of variety over another. From that standpoint, man has intervened genetically with crops for centuries.

Now, if GMOs are thought of, general, of using recombinant DNA technology to put in a gene from some very, very different organism - into another organism. That has a much shorter history.

TW: And is that happening in wheat?

LS: Genetic-modified wheat is clearly on the table once again. If you go back 10 years ago, I think most people would have said 'no one is going to look seriously at genetically-modified wheat; there's no market for that.' But I think that's changing and there are clearly groups that are looking at developing genetically-modified wheat that has enhanced resistance. And there are groups around the world, cloning different genes.

TW: If wheat rust has had these cycles, and every cycle we've found a way to solve it - because we still have wheat - then the question becomes 'Do we need to do it this genetically-modified way, if the Norman Borlaug way of more naturally finding genetic combinations to breed worked back then?

LS: I don't know if I have a good answer for that. It's clearly a question of looking at efficiency and a larger, I think, a global perspective, in terms of developing a system one can modify more readily, and reduce the large threshold that it takes to develop new varieties and put in new resistance, which you run into with the classical breeding system. And so I think that's the driving force - is there a way to more efficiently do the same thing, but with a shorter lag time?

TW: Do you have any opinions on whether that's the way to go?

LS: I think I'm going to have to pass on that one. The use of GMOs is clearly a political issue. We have GMO corn and soybeans and cotton, and so it's not a technical, not a scientific issue. It's clearly a political issue."

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