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). 

Where have the fall colours gone?

 All last week I could barely contain my excitement: I was going to visit my parents for the weekend.  Although I love my parents dearly, it was actually fall I was looking forward to seeing.  Fall is best discovered in the country, where its smell and splendour are evident everywhere; while raking the yard, grouse hunting, pumpkin picking, and most of all – gazing at the beautiful coloured leaves.



Dramatic hobblebush leaf

Fall colour-seeking tourists, also called ‘leaf peepers’, travel from all over the country to visit my hometown area during the fall.  The huge assortment of deciduous tree types, combined with the rolling hills, perfectly displays Mother Nature’s artwork.  How lucky am I to have grown up in such an area, where I was able to take in the magic every fall from my front porch.

On the drive up last Saturday morning, I too turned into a ‘leaf peeper’; checking out the usual colour hot spots.  Upon passing R Lake – a small pond backed by a large rolling hill – my heart sunk.  The reds, oranges, and yellows were few and far between; instead browns and bare branches dominated the scenery.

As soon as I got out of the car at my parents’ house, I ran to the front yard to check out their beautiful red maple.  This tree is an attention getter.  It sits right at the corner of my parents’ lot, and could stop the traffic driving by during the fall.  Then, it normally has leaves that are fiery red, spotted with mustard yellow; a perfect backdrop to my family’s annual autumn photo.  Although many leaves were still on the tree, there were more boring browns than striking reds.

Was I just too late?  Did I miss it?  I couldn’t have.  Normally, the most intense colours weren’t on display until Thanksgiving weekend, and I was a week early.  So why were the colours so drab and the leaves shedding so early this year compared to those in the past?