Abstract
Several cold-hardy grasses have been shown to have ice-binding proteins (IBPs) that protect against freeze-thaw injury. Here, we looked for IBP activity in an Alaskan coastal grass that had not previously been examined, Leymus mollis (Pooidae). Rhizome tissue had strong ice-structuring and ice recrystallization inhibiting (IRI) activities, indicating the probable presence of IBPs. The gene sequence of an IBP was obtained. The sequence encoded a 118-amino acid IRI domain that contained eight repeats. A 3D structure of the IRI domain was predicted from the structure of the IRI domain of the perennial ryegrass Lolium perenne. The predicted structure appeared to have the same eight beta-roll coils found in the L. perenne IBP.
Highlights
Within the grass family (Poaceae), the subfamily Pooideae includes many cold-adapted grasses including wheat, barley and forage grasses
We describe a related ice-binding proteins (IBPs) from a pooid grass from Utqiaġvik (Barrow), Alaska, Leymus mollis. This site, at 71.3° N, is the highest latitude at which IBPs have been examined in a grass and is 9° higher in latitude than the site where D. antarctica was sampled in the southern hemisphere
We show that an extract of the grass has strong ice-shaping and recrystallization inhibition properties and predict its structure based on the structure of L. perenne IBP
Summary
Within the grass family (Poaceae), the subfamily Pooideae includes many cold-adapted grasses including wheat, barley and forage grasses. Keywords Leymus mollis, ice-binding protein, Arctic, Alaska, Pooidae, dune grass, Beaufort Sea version 2 (revision) These grasses have developed a large family of ice-binding proteins (IBPs) that protect the plants from freezing damage (Sandve et al, 2008).
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