FarÃas J G
Universidad de La Frontera, Chile
Title: Characterization of antifreeze activity in apoplastic extract of Deschampsia antarctica
Biography
Biography: FarÃas J G
Abstract
Deschampsia antarctica Desv. is a vascular plant species that colonized maritime Antarctica exhibiting extreme freezing
tolerance (-27°C). Th is has been associated with apoplastic antifreeze activity. Antifreeze proteins (AFPs) have the ability
to bind to the growing surface of ice crystals inhibiting their growth; however, this activity has been poorly characterized in
this species. Th erefore, the aim of this work is to characterize the antifreeze activity of apoplastic extracts from D. antarctica.
To understand how this plant can tolerate freezing temperatures year-around, and in order to evaluate the potential antifreeze
activity of apoplastic proteins from D. antarctica as future applications, experiments have been developed in cold-acclimated
and non-aclimated plants. To identify the best apoplastic proteins accumulation aft er plant cold-acclimation, apoplastic
extracts were quantifi ed every four days for 21 days of low temperature exposure. Antifreeze activity was determined by ice
recrystallization inhibition (IRI), thermal hysteresis activity (TH) and ice crystal growth in dilution series of apoplastic extracts.
Th e results indicate that the minimum IRI activity was evident in extracts with a concentration equal to 0.005 μg/μl at coldacclimated
condition, while in non-aclimated plants the IRI activity was lost at 0.05 μg/μl. At concentration equal to 2.5 μg/μl,
ice crystals showed a bipyramid shape and a TH equal to 0.4°C. In conclusion, we observed that cold-acclimation increased
apoplastic antifreeze activity, obtaining higher IRI but low TH in these apoplastic extracts. Th is high IRI is remarkable and
further studies are needed to characterize the apoplastic extract to associate this activity to apoplastic antifreeze proteins which
could be of interest for later studies as a cryoprotectant.