A Chlorophyllic Conundrum

Editor’s Note:  Special Thanks to Sree Subha Ramaswamy for the amazing photos!

by Pavan Kaushik – On a summer afternoon, I lazed under the lone Kadamba tree amidst an out-of-place green lawn in my tropical campus. The deciduous canopy shed its leaves. My sleep was punctuated with gusts of wind that left a shower of yellow. But one leaf caught my eye. It was yellow, but with splotches of green all over. On closer inspection, it was green rings. Rings of different sizes and shades. It looked like ink blots and coffee stains but green. As though the tree was putting me through a Rorschach test. I dismissed it off as just one wonky leaf.

IMG_20171022_141737My partner in crime, unassailable that she is, went around scanning the leaf litter. Moments later, she had over a dozen different leaves, each more unlike the previous. What could it be that made so many intricate patterns on the leaves? Is it just a tree with messed up leaves? A microbial infection? Or is it the trees’ way to cut its losses by recuperating as much resources as possible? Contrary to appearances, the tree isn’t absorbing chlorophyll. They are mostly just shutting down chlorophyll synthesis. This is a fundamental side effect of homeostasis(or lack of).

Everything gets messy over time; unless you put in an effort to clean the mess. What makes your home into a wreck; your best gift in school, a cycle go rusty; the green leaf into yellow. Entropy. Similarly, everything in a cell degrades over time albeit at different rates. And if not replenished back, it will just disappear (actually, pile up as cellular waste). And at the end of the day, what remains is a mush of different pigment molecules, all decaying at different rates, their ensemble creating the varieties of hues, vibrant to dull over time. Imagine it like the bicycle that you stopped riding after high school. Initially, the tyres start “losing air”, followed by a flat tyre. The metal parts start to rust. The cycles of heating and cooling warp the metal frame. The UV causes the seat to crack, makes the plastic brittle, and fades the paint. The rust spreads into every cranny. All moving parts cease to move. On the same lines, after the orchestrated disowning of the leaf by the tree, a whole new entropic drama begins, converting all hues and patterns to Grey dust.

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But, this still doesn’t explain the rings! An artifact? Infection? Biophysical drama? I do not know. I have tried to no avail. But if you do have an explanation or a hypothesis, do share it in the comments!

  One thought on “A Chlorophyllic Conundrum

  1. Rudra Banerjee
    May 25, 2018 at 11:26 am

    Hi Pavan. Nice to read an interesting observation from you. I have an explanation for these green patches. I could still remember, when we were in NCBS for the Chemical ecology training, there was a nice presentation at IISc. regarding “green Island and leaf minors”. This is all I could remember. Green Islands are basically small, green patches on the surface of an otherwise senescent leaf. These green islands are created by leaf minors which in return obtain all the nutrients from these green patches. There is an obligatory relationship between the gut endosymbiont Wolbachia sp. and the leaf minors which promotes the formation of these green patches. Removal of the endosymbionts would result in the disappearance of these patches as well as an increase in mortality of the leaf minors.

    You can read more from the following paper-
    http://rspb.royalsocietypublishing.org/content/early/2010/03/24/rspb.2010.0214

    Like

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