2:19 a.m. September 25, 2013

A New Plant Organelle!

This month, researchers from French National Institute for Agricultural Research (INRA) announced the discovery of a new plant organelle responsible for tannin production. It’s an insanely cool discovery, but one of those bits of science news that seems inherently indigestible, unreadable, and boring. That is ridiculous. This is science news at its finest.

(Additionally, those among us who seek the smug afterglow that stems from unleashing nerdy dinner party trivia would be well advised to commit this piece to memory or make a festive cheat sheet. Breaking science news and wine trivia? My, you look sharp in that sweater vest!)

Now on to the science.

Tannins, of which you may be familiar by way of tea or wine, comprise a large group of compounds that either shrink or bind and precipitate proteins. Stemming from the German word for tree, tanna, their name reflects the wood tannins that are used for treating animal hides. Have a flexible, thin animal hide but wish it was thicker and tougher? Well, you might just want to use a compound that shrinks proteins and binds them together! (Learn This One Weird Trick That Cows Hate That Shrinks Proteins And Binds Them Together So That You Can Wear The Toughened Flesh Of Beasts .)

Tannins are found all over the plant kingdom; many, many different kinds of plants make them in multiple types of tissues, including bark, seeds, leaves, buds, and roots. Plants, who are not gifted with the ability to flee from their enemies, instead use must chemical weapons to stand and deliver. By producing chemicals that, say, keep other plants from rooting near you, or deter animals from munching on you at inopportune times, or keep bugs from ruining your game, plants can effectively fight nature where she stands. Tannins are of this chemical ilk; not only they are bitter and astringent to deter wandering herbivores, they function as plant sunscreen and might also deter pests.

Until this discovery, no one knew exactly where in the cell the tannins were being produced, which is bananas. It’s not like tannin is always some rarified substance; some kinds of plant tissues can be as much as fifty percent tannin by mass! That’s a lot of tannin. Given this, it’s even more insane that not only have we figured out how the cell does its tannin business, we’ve found a brand-spankin’ new organelle that makes them: the tannosome.

Yes indeed, plants make tannin in an organelle that is new to science. Organelles, as one might surmise from their biologically adorable name, are like the organs of a eukaryotic cell. Whereas humans have colons, livers, and hearts, cells have their own version of specialized things that do stuff. For example, mitochondria are the powerplants, ribosomes read genetic blueprints and build the corresponding proteins, the Golgi apparatus packages cellular products prior to their shipping out of the cell, lysosomes are the trash dissolving squad, and smooth endoplasmic reticulum runs the intracellular trucking union, just to name a few.

Like most organelles, tannosomes are sequestered in their very own little space by a lipid bilayer, a fatty balloon to keep their bits away from other bits. This separation is a big deal because, as the aforementioned animals skins well know, tannins are protein precipitators. They like to bind shit, clump it up. On a kids show, tannins would be described as a special magic spoon that, when stirred in soda, could cause all the sugar to clump together and fall - precipitate to the bottom of the glass. Except tannin does this to proteins. So yeah, inside the cell, not everyone wants to play with tannins.

But on an organismic level, humans play with tannins all the time. For instance, when you eat or drink something that is high in tannins, like a shitty young wine or a mugful of plain, black tea, it results in that weird kind of drymouth. (Nuts that you can eat raw, like almonds and walnuts, do this too and are also high in tannins.) The sticky pucker is due to the astringency of the tannins, who gleefully bind proline-rich salivary mucin, precipitating them out of the solution that is your mouth juice. Yes, those wine tannins go straight for your mucus; the presence of the newly clumpy goo increases the friction between the surfaces in your face hole, which your masticating orifice registers as a dry roughness. Very sexy.

If thinking about mucous and wine-mouth doesn’t make you want to splurge on a wine naturally high in tannins, like a puckering tempranillo, fret not: future research that will undoubtedly result from this unexpected finding should be quite interesting. Since scientists now know where to find tannin production, work can proceed to manipulate tannins in exciting ways, which could lead to changes in a wide variety of practical applications, everything from industrial anti-corrosives to less desiccating wines.

As the study’s co-author, Charles Romieu excitedly told Scientific American, “It was the last frontier in plant biology.”

Or was it?

My cell bio classes let me to believe that the organelles of a cell are generally thought to be a pretty well known, established thing. I don’t recall the information being taught with a question mark or the kind of open-ended shoulder shrug that accompanied most of my molecular biology courses. Prior to this study, were I to to draw up a plant cell from memory, I really wouldn’t give much thought to the notion that there could be undiscovered organelles. That my bar napkin doodle would be incomplete.

But that’s just the kind of ignorant complacency for which these wonderful discoveries are the remedy. No one thought there was more than one green organelle in plants - it was chloroplast or get the fuck out. But this discovery of a second green organelle, the long-sought tannin production factory, is a great reminder that nothing chokes curiosity more than the arrogant belief that what you know is true and complete. The announcement of a new plant organelle is science at its most beautiful, a reminder that there is so much more to learn, that we know so little. A wine-soaked wink and a dry-mouthed smile at all the wonders that stare us in the face, every single day.