Remember how you've been taught in elementary school that red and yellow autumn leaf colors simply appear after the...
Remember how you've been taught in elementary school that red and yellow autumn leaf colors simply appear after the degradation of chlorophyll that masked these pigments, and that they served no function. That ain't quite so.

While for yellow/orange color (Xanthophyll pigments are carotenoids, like beta-carotene) it is indeed true, it has been shown (only in 2003!) that in many plants red/purple color (Anthocyanin are phenols, like Litmus, similar to пурген [1]) is not simply unmasked but rather synthesized de novo by leaves in mid-senescence i.e. once roughly half of chlorophyll has been degraded [2].

This, naturally, leads to the question - what for? You can read the poorly written paper below, full of wild fantasies and speculations [3] why Northern Europe allegedly became dominated by yellow autumn leaves, but North American trees allegedly continued to need the bright red [4].

http://www.dailymail.co.uk/sciencetech/article-2043891/Scientists-solve-riddle-leaves-change-colour--fall-shortly-after.html

"What Do Red and Yellow Autumn Leaves Signal?" Simcha Lev-Yadun, University of Haifa, Israel
http://research.haifa.ac.il/~biology/simcha/Publications/I90.pdf

http://en.wikipedia.org/wiki/Autumn_leaf_color

[1] Anthocyanins temporarily color the edges of some of the very young leaves as they unfold from the buds in early spring. They also give the color to cranberries, red apples, blueberries, cherries, strawberries, and plums, which is part of the reason that if you eat too much тебя проносит (Phenolphthalein=пурген).

[2] The amino acids released from degradation of light harvesting complexes are stored all winter in the tree's roots, branches, stems, and trunk until next spring when they are recycled to re‑leaf the tree.

[3] Or a much better one: "Unravelling the evolution of autumn colours: an interdisciplinary approach" (2011), Archetti et.al.
http://bioserv.fiu.edu/~leed/articles/TREE-Autumn-2009.pdf

[4] Actually, compared to Western Europe, North America provides many more arbor species (more than 800 species and about 70 oaks, compared to 51 and 3 respectively in Western Europe) which adds many more different colors to the spectacle. During ice ages in North America, species were protected in more southern regions along north–south ranging mountains, which was not the case in Europe. Still evolutionary role of red color is not understood and not really studied yet.

#sciencesunday  
http://www.dailymail.co.uk/sciencetech/article-2043891/Scientists-solve-riddle-leaves-change-colour--fall-shortly-after.html

Labels: Oleg Zabluda, sciencesunday

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