'Pyramiding' genes leads to better wheats and TAMU Regents Award

03/02/05



Dr. Lloyd Nelson (right) and his assistant, Jimmy Crowder, transplant selected turf-type ryegrass plants in a greenhouse at the Texas A&M University System Research and Extension Center at Overton. Nelson, small grains plant breeder with the Texas Agricultural Experiment Station, recently was named a Regents Fellow with Texas A&M. (Texas Cooperative Extension photo by Robert Burns)

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OVERTON – The Texas A&M University Board of Regents has named Dr. Lloyd Nelson as the recipient of the Regents Fellow Service Award. Nelson is an Overton-based researcher and plant breeder with the Texas Agricultural Experiment Station.

Nelson is known for his work in developing 27 wheat, oat, barley and rye and ryegrass cultivars. One of the ryegrasses, TAM 90, is one of the most widely grown in the United States. Two of his more recent releases, Axcella and Panterra, both dwarf annual ryegrasses, show promise as winter turfs for sports fields and overseeding of home lawns.

The success of TAM 90 and other releases were due in part to their improved resistance to plant diseases. Nelson's research was been cited by the awards committee as an example on how to "pyramid" genes for disease resistance.



Dr. Lloyd Nelson transplants selected turf-type ryegrass plants in a greenhouse at the Texas A&M University System Research and Extension Center at Overton. Nelson, small grains plant breeder with the Texas Agricultural Experiment Station, recently was named a Regents Fellow with Texas A&M. (Texas Cooperative Extension photo by Robert Burns)

Full size image available here

"Pyramiding genes" is just what it sounds like. For any trait, multiple genes are usually at play. For example, when developing septoria-resistant wheats, Nelson identified plants that showed tolerance during seedling stage. Wheat seedlings were inoculated with septoria in the greenhouse. Plants showing resistance during the latent period – the length of time from inoculation to the first symptoms – were selected.

Other plants were selected that showed a longer time of first symptoms to when the septoria fungus produces fruiting bodies. The disease spreads within the field by when rain splashes the fruiting bodies from plant to plant.

"What we were doing – simplified – was lengthening the time for the disease to cycle," Nelson said. "By cycling, we mean that time between inoculation to development of fruiting bodies."

A few days' difference in this disease cycling time could make a huge difference in the disease's effect upon wheat yield and quality, he said.

He then crossed these various selections, stacking or "pyramiding" the different genes. The Regents Fellow Service Award is based on achievements spanning a career. Only two experiment station scientists receive the award in a given year.

Among other achievements by Nelson cited in the Regents Fellow award was his becoming recognized worldwide for his work in breeding for wheat disease resistance. Nelson organized the first International Septoria Conference in 1976 and has served as a consultant for wheat breeding programs in Brazil, Argentina, Paraguay, Uruguay, Chile and Bolivia. In 2004, he was invited to speak at an international conference in China on the development of disease resistance in a super wheat.

He has also been chosen as a Fellow in the American Society of Agronomy and the Crop Science Society of America.

Nelson and Nancy, his wife of 36 years, have lived in the Overton area for 29 years.

They have three adult children, Lora, Adam and Sara.

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