Newswise — Iowa State University researchers have discovered a way to increase corn's frost resistance by incorporating 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 in times of stress from heat, cold or water loss. Their research showed an improvement of 2 degrees Celsius in the freezing 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 Academy of Sciences.
Originally a tropical crop, corn is naturally frost sensitive. This discovery could help corn survive late-spring and early-fall frosts and allow production of the crop in areas with climates previously considered too cold. Wang says the tobacco 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 cold temperatures," Wang said. "During the acclimation process, many genes that protect the plants from stress are turned on. The tobacco gene we inserted encodes a protein that mimics the acclimation effect and activates corn's natural responses to stress faster than through natural acclimation."
The tobacco gene carrying the activator protein is NPK1. It was inserted into corn through Agrobacterium-mediated transformation, which uses a soil bacterium as the vector of gene transfer. Transgenic corn lines were exposed to subzero 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 of such a gene in corn. While the corn lines we have generated so far are not appropriate for the marketplace, they are important 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 plants to make them more resilient," Wang said. For example, Wang and her associates have already completed tests showing the tobacco 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 to test 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 and Massachusetts General Hospital, Boston; and Huixia (Sylvia) Shou, who wrote her dissertation on the project as a graduate 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 is dedicated to becoming one of the world's leading plant science research institutes. More than 200 faculty from the Colleges of Agriculture, Liberal Arts and Sciences, Family and Consumer Sciences and Engineering conduct research in nine centers of the institute. They seek fundamental knowledge about plant systems to help feed the growing world population, strengthen human health and nutrition, improve crop quality and yield, foster environmental sustainability and expand the uses of plants for biobased products and bioenergy. The institute is supported through public and private funding.
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