Submitted to: Plant Molecular Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2002
Publication Date: 8/1/2002
Citation: HUANG, T., NICODEMUS, J., ZARKA, D., THOMASHOW, M., WISNIEWSKI, M.E., DUMAN, J. EXPRESSION OF AN INSECT (DENDROIDES CANADENSIS) ANTIFREEZE PROTEIN IN ABIDOPSIS THALIANA RESULTS IN A DECREASE IN PLANT FREEZING TEMPERATURE. PLANT MOLECULAR BIOLOGY REPORTER. Vol. 50, pgs. 333-344, August 2002. Interpretive Summary: Freeze damage to fruit crops by late spring frosts results in millions of dollars of lost revenue for producers each year and higher commodity prices for consumers. In particular, blossoms of fruit trees have little or no tolerance to freezing temperatures. Current methods of frost protection can be expensive, inadequate, and in some cases, environmentally unfriendly. Therefore, there is a need to explore new methods of frost protection. The current research examined the effect of expressing an insect, antifreeze protein in Arabidopsis on the freezing response of the plant. Antifreeze proteins have been identified in fish, insects, and plants, and are known to lower the freezing point of solutions within the parent organism, and bind to growing ice crystals, thus restricting their growth so that only small crystals form which are less injurious than large, unchecked crystals. Insect antifreeze proteins are among the most active antifreeze proteins that have been identified so far. In the current research, the insect antifreeze protein was found to be expressed in the transgenic plants. Antifreeze protein extracted from the transgenic plants was functional. Transgenic plants froze at a lower temperature than non-transformed plants, however, the plant did not survive freezing any better than the non-transformed plants. Further research will explore the use of other antifreeze proteins and ways of improving the effectiveness of antifreeze proteins so that they will have a significant impact on frost tolerance.
Technical Abstract: Transgenic Arabidopsis thaliana plants which express genes encoding insect, Dendroides canadensis, antifreeze proteins (AFP) were produced by Agrobacterium-mediated transformation. The antifreeze protein genes, both with and without the signal peptide sequence (for protein secretion), were expressed in transformed plants. Thermal hysteresis activity (indicating the presence of active AFPs) was present in protein extracts from plants expressing both proteins and was also detected in leaf apoplast fluid from plants expressing AFPs with the signal peptide. Transgenic lines did not demonstrate improved ability to survive freezing when compared to wild type. However, when cooled under four different regimes, transgenic lines with AFPs in the apoplast fluid froze at significantly lower temperatures than did wild type, especially in the absence of extrinsic nucleation events.