AFPs - A bit of ecology, physiology, and biochemistry



My deer watch on a chilly Friday
morning

On Friday morning, I was freezing to death standing on my deer watch.  The sun hadn’t come up yet, and wind was blowing right in my face.  The freshly fallen snow was soaking my boots and pants, and sent extra chills up my spine.  These freezing temperatures, howling wind, and inches of snow surely meant death to all of the once vibrant and colourful herbs.  But beneath the accumulating snow, there were a few green survivors trying to hold on.  How were they not frozen when I – dressed in layers of long underwear, jackets, and gloves – clearly was?



In most herbaceous plants, ice crystals begin to form within the liquid-filled intercellular spaces of cells when winter comes.  These crystals continue to expand, bursting and killing the cell, and eventually the whole herbaceous plant.  However, some plants – along with animals and insects – produce antifreeze proteins (AFPs) in their bodies to adapt to cold environments.  Reduced day length and cold trigger production of AFPs in many plants to make them freeze tolerant (capable of tolerating some cold) or freeze avoidant (avoiding freezing altogether).