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A carrot leucine-rich-repeat protein that inhibits ice recrystallization
D Worrall1, L Elias, D Ashford
1The Plant Laboratory, Biology Department, University of York, Post Office Box 373, York, YO1 5YW, UK.
Abstract:
Many organisms adapted to live at subzero temperatures express antifreeze proteins that improve their tolerance to freezing. Although structurally diverse, all antifreeze proteins interact with ice surfaces, depress the freezing temperature of aqueous solutions, and inhibit ice crystal growth. A protein purified from carrot shares these functional features with antifreeze proteins of fish. Expression of the carrot complementary DNA in tobacco resulted in the accumulation of antifreeze activity in the apoplast of plants grown at greenhouse temperatures. The sequence of carrot antifreeze protein is similar to that of polygalacturonase inhibitor proteins and contains leucine-rich repeats.
Insights
Antifreeze proteins (AFPs) help organisms survive freezing temperatures. A carrot protein functions like fish AFPs, and expressing it in tobacco plants enhances their freezing tolerance.
Area of Science:
- Plant biology
- Biochemistry
- Cryobiology
Background:
- Organisms in subzero environments often produce antifreeze proteins (AFPs) to enhance freezing tolerance.
- AFPs, despite structural diversity, inhibit ice crystal growth by interacting with ice surfaces and lowering the freezing point of solutions.
Purpose of the Study:
- To investigate the antifreeze properties of a protein purified from carrots.
- To determine if the carrot AFP gene can confer freezing tolerance to plants.
Main Methods:
- Purification of a protein from carrot with antifreeze activity.
- Functional characterization of the carrot protein's interaction with ice.
- Expression of the carrot complementary DNA (cDNA) in tobacco plants.
- Analysis of antifreeze activity in transgenic tobacco plants.
Main Results:
- A carrot protein was purified that exhibits functional characteristics of AFPs, including ice-binding and freezing point depression.
- Expression of the carrot AFP cDNA in tobacco plants led to the accumulation of antifreeze activity in the plant apoplast.
- The carrot AFP sequence shows similarity to polygalacturonase inhibitor proteins and features leucine-rich repeats.
Conclusions:
- Carrots possess a functional antifreeze protein similar to those found in fish.
- Genetic engineering of plants with carrot AFP can enhance their freezing tolerance, offering potential applications in agriculture.