ABSTRACT
This chapter aims to quantify ice nucleation activity in winter rye leaves grown at 20°C, at 5°C, and at 5°C followed by a shift to 20°C for 6 days. Ice nucleation activity was determined in intact leaf segments using the test tube assay. Cold-grown rye leaves exhibited higher ice nucleation activity at any temperature warmer than -12°C. The capacity of winter rye leaves to survive an ice nucleation event was determined by allowing leaf samples to freeze spontaneously and then measuring ion leakage from the tissues to estimate injury. The process of forming ice is clearly altered during cold acclimation so that ice nucleation does not limit the frost tolerance of the leaf. Antifreeze proteins isolated from freezing-sensitive fish and insect species inhibit ice crystal formation. In frost-tolerant organisms, extracellular ice formation is controlled by two distinct classes of ice-binding proteins: ice nucleating proteins and antifreeze proteins.
