In addition, apoplastic fluids from the leaves of non-acclimated and cold-acclimated plants exhibit antifreeze activity (Bravo and Griffith, 2005). antarctica, hexagonal forms of ice crystals (Bravo and Griffith, 2005) characteristic of those growing in the presence of AFPs have been observed ( DeVries, 1986). Many organisms, including insects, fish, bacteria, fungi, and plants, accumulate antifreeze proteins (AFPs), which bind to the faces of ice crystals during freezing in order to inhibit their growth ( Duman and Olsen, 1993 Ewart et al., 1999 Griffith and Yaish, 2004).ĭuring the freezing of apoplastic extracts of D.
In organisms that survive freezing, ice forms outside the cells, and its growth must be minimized to reduce both cellular dehydration and physical damage ( Grifith and Antikainen, 1996). This plant is capable of growing in the summer because it maintains ~30% of its optimum net photosynthesis at 0 ☌ ( Xiong et al., 1999). antarctica is covered by snow for 6–7 months of the year, during the summer it is frequently exposed to constant freeze–thaw cycles, when the average daily temperature is 4 ☌ ( Day et al., 1999 Smith, 2003). Because the maritime Antarctic environment is permanently cold, this perennial must complete its life cycle under constant low-temperature conditions ( Day et al., 1999 Alberdi et al., 2002 Smith, 2003). This vascular plant grows in favourable locations along the west coast of the Antarctic Peninsula ( John et al., 2009). An in silico analysis suggested that the fluctuations presented by the three-dimensional structures of DaIRIPs help to explain the presence of certain DaIRIPs in apoplastic extracts under the cold acclimation conditions evaluated.Īntifreeze proteins, apoplastic extracts, cold acclimation, Deschampsia antarctica, ice recrystallization inhibition, thermal hysteresis Introductionĭeschampsia antarctica is one of the two species of angiosperms that have colonized the maritime Antarctic ( Smith, 2003). antarctica improved the yield of apoplastic proteins, and resulted in an increase in the antifreeze activity of apoplastic extracts. antarctica ice recrystallization inhibition protein 1 (DaIRIP1) and 55% with DaIRIP3. Protein sequencing allowed their identification with >95% probability. The highest content of apoplastic proteins with antifreeze activity was obtained at between 12 and 16 days of acclimation. antarctica plants were subjected to 22 days of cold acclimation at 4 ☌. Antifreeze proteins present in apoplastic extracts were purified by ice affinity purification, and their identity was determined by protein sequencing. antarctica on the accumulation of apoplastic proteins with antifreeze activity. This work focuses on the effect of cold acclimation of D. One of the main factors associated with its tolerance to low temperatures is the presence of apoplastic proteins with antifreeze activity. Deschampsia antarctica has managed to colonize the maritime Antarctic.
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