By Carol Flaherty
MSU News Service

10/13/99 - BOZEMAN – Sometimes we get the idea that all a geneticist has to do is put a dollop of this into a drop of that and voila, a new plant variety is born.

But the truth is that behind the scenes, it's a real grind.

Literally.

Researchers, students and lab technicians have spent thousands of hours over the past decade grinding up plants. That's an early step in determining whether a new tree, tomato or potato has desirable characteristics, like being able to resist insects and diseases without the help of pesticides.

But first, there was always the slow grind.

Norm Weeden, head of Montana State University's Plant Sciences Department, decided there had to be a better way to grind than by hand or using a drill press one sample at a time, especially because a researcher may have to check the DNA of a thousand samples at a time.

What Weeden and two other inventors created is called the "matrix mill." It looks a bit like a high-tech waffle iron and is used to grind 96 samples in a minute of plant or animal tissue in preparation for extracting DNA. Comparable work before probably would have taken between 5 and 10 hours. The decreased time translates to decreased cost, and cost has often limited the application of DNA marker technology to more profitable plant varieties like ornamentals and crops.

Weeden recently used the mill to combine 10 different disease-resistance genes for peas into breeding lines that now are used by breeders around the world.

"Marker selection allowed the assembly of a whole constellation of genes," said Weeden.

Weeden expects the matrix mill to become a common tool in breeding better home garden and landscape plants as well as crops, because it minimizes the hassle that otherwise accompanies genetic screening. Marker-assisted selection of plants, or even livestock, is a technique Weeden considers a better way to work once you get past "the grind."

DNA markers are short recognizable fragments of DNA that are inherited with a commercially important genetic trait. When scientists see such a marker in a new breeding line they are testing, they can assume they've succeeded in getting a characteristic into a plant.

The first biochemical marker was developed about 1974, and it let breeders determine whether new types of tomatoes could resist a root-boring worm. Before then, it was necessary to actually grow the worms, grow the tomatoes, put the two together for a season, then analyze the root to see how the plants did.

"Use of the marker in tomato breeding quickly spread to all the commercial labs breeding tomatoes," says Weeden.

Though scientists don't have detailed DNA maps of all living organisms, they have many markers of importance, from those of giant redwoods and cold-tolerant roses to livestock. In general, the matrix mill wouldn't be used for studying human genetics, because that is usually done one-at-a-time with blood samples. But plant breeders may have a field full of potential varieties, all in need of testing at the same time. In that situation, the matrix mill will be a time and money-saver.

Weeden did most of the work on the matrix mill while still at Cornell University and the New York State Agricultural Experiment Station before he began at MSU in the fall of 1999. Now, after several years of tweaking with his two machinist co-inventors, Joe Celeste and Dale Loomis, the matrix mill has been tested in other labs and is now available commercially.