York researchers identify 'antifreeze' protein in carrots
Posted on 1 October 1998
A team of plant biologists at the University of York have isolated the first plant antifreeze protein. The naturally occurring 'antifreeze' in carrots might lead to improved frozen foods, more efficient freezing of tissue for medical use and better frost tolerance for crops.
The discovery of the antifreeze protein by a team from the Plant Stress Response Group led by Professor Dianna Bowles, is reported in the international journal, Science, this week.
"Antifreeze proteins act in a different way to the antifreeze you put in your car radiator," said Maggie Smallwood the senior scientist involved in the project. "These proteins specifically bind to ice crystals and stop them growing." The stress response team showed that extracts from carrots which had been growing under cold conditions could prevent ice crystal growth. They went on to purify the protein which kept the ice crystals small and identify the gene which encoded the protein. They transferred the gene into a model plant which does not normally express antifreeze activity and showed that extracts from these plants stopped ice crystals growing.
Dawn Worrall, a postdoctoral scientist working on the project, pointed out that much of the damage which plants and other organisms experience when they freeze is due to the growth of ice crystals over time. "Large ice crystals disrupt tissue structure more than small ones and regulation of ice crystal growth may be important to survival of a carrot root in the field over winter," she said.
Professor Dianna Bowles expects the carrot antifreeze protein to have a number of potential applications. "Simple natural extracts from carrots may be useful in enhancing the quality of frozen food products and prolong their life in the domestic freezer," she says. "The pure carrot protein might also prove to be useful in cryoprotection (freezing) of medical tissues. In addition, transfer of the gene into temperate crop species may increase their frost tolerance and widen their season or region of cultivation. Similarly there may be applications for horticultural species that suffer from early frosts."
The antifreeze protein discovered in this study is produced by a carrot plant: it is an example of a commercially important product that can be grown in a 'plant factory'. Plants can be used to produce large quantities of industrial or speciality chemicals in a highly energy-efficient manner. Researchers in the Plant Laboratory at the University of York are exploring the potential of this environmentally friendly technology to manufacture products for a wide range of industries.