01-30-04

TRANSGENIC CORN DEVELOPED AT IOWA STATE HAS GREATER FROST TOLERANCE THANKS TO TOBACCO GENE

AMES, Iowa -- Iowa State University researchers have discovered a way to increase corn's frost resistance byincorporating a tobacco gene that activates corn's natural defense systems against cold temperatures.

Kan Wang, associate professor of agronomy and director of the Center for Plant Transformation led the research team.The tobacco gene they inserted carries protein that activates corn's defense systems to stabilize and protect cells intimes of stress from heat, cold or water loss. Their research showed an improvement of 2 degrees Celsius in thefreezing tolerance of the transgenic corn compared to traditional corn lines.

The research will be published next week in the early online edition of the journal Proceedings of the National Academyof Sciences.

Originally a tropical crop, corn is naturally frost sensitive. This discovery could help corn survive late-spring andearly-fall frosts and allow production of the crop in areas with climates previously considered too cold. Wang says thetobacco gene appears to have no impact on corn plant growth under normal growth conditions.

"Plants naturally acclimate to environmental stresses, for example when they are gradually introduced to coldtemperatures," Wang said. "During the acclimation process, many genes that protect the plants from stress are turnedon. The tobacco gene we inserted encodes a protein that mimics the acclimation effect and activates corn's naturalresponses to stress faster than through natural acclimation."

The tobacco gene carrying the activator protein is NPK1. It was inserted into corn through Agrobacterium-mediatedtransformation, which uses a soil bacterium as the vector of gene transfer. Transgenic corn lines were exposed tosubzero temperatures, either under a graduated freezing condition or a constant freezing condition.

"To our knowledge, our research is the first in which freezing tolerance was achieved through constant expression ofsuch a gene in corn. While the corn lines we have generated so far are not appropriate for the marketplace, they areimportant for further research." Wang said.

"My main interest is to unravel the stress response systems of plants. This project demonstrated one response system,but the more we understand biologically about plants' stress systems, the more we will know about how to enhance plantsto make them more resilient," Wang said. For example, Wang and her associates have already completed tests showing thetobacco gene enhanced drought tolerance in the transgenic corn lines.

The researchers also have generated transgenic soybeans and rice by incorporating the same tobacco gene, and plan totest these plants in several biotic stress conditions, which can be caused by insects, fungus or bacteria.

Wang collaborated on the research with Jen Sheen, associate professor of genetics, Harvard Medical School andMassachusetts General Hospital, Boston; and Huixia (Sylvia) Shou, who wrote her dissertation on the project as agraduate student of Wang's. Shou is currently on the faculty of Zhejiang University in China.

The research was funded by a grant from the National Science Foundation's Plant Genome Research program.

The Center for Plant Transformation is part of the Plant Sciences Institute at Iowa State University. The institute isdedicated to becoming one of the world's leading plant science research institutes. More than 200 faculty from theColleges of Agriculture, Liberal Arts and Sciences, Family and Consumer Sciences and Engineering conduct research innine centers of the institute. They seek fundamental knowledge about plant systems to help feed the growing worldpopulation, strengthen human health and nutrition, improve crop quality and yield, foster environmental sustainabilityand expand the uses of plants for biobased products and bioenergy. The institute is supported through public andprivate funding.

-30-