The Tea Lover's Organelle: Tannosome

A team of French and Hungarian scientists identified an organelle responsible for producing the chemical that gives tea, wine, and unripe fruit a bitter flavor according to Scientific American's blogger Jennifer Frazer.

The tannosome produces tannins, the bitter chemicals that enhances flavor but deter many herbivores. Tannin denatures proteins in the herbivore, making it difficult for the animal to process its food and produce energy at a regular rate. For more information on tannins specifically, see this explanation of the biotoxins from Cornell.

Previously, scientists assumed that the rough endoplasmic reticulum produced the tannins, which were then stored in the vacuoles. Instead, the team found that they are produced within the chloroplasts, and stored in special vesicles  called tonoplasts that prevent the chemicals from disintegrating their own cell's proteins.

Photo credit: Jean-Marc Brillouet, et al. (from the original research paper in the Annals of Botany).
The new process, proposed by the researchers, suggests that tannosomes are found within the inner membrane of the vascular plants' chloroplasts. The tannosomes make the tannins, which are then shuttled by a vesicle into the vacuole where they are stored inside a tonoplast, which separates them from the other contents of the vacuole.

Since organelles are useful in separating biological processes, it is not entirely surprising that tannins require their own production centers. It is worth noting that even the collection of organelles may still increase as scientists turn their attention to new processes and chemicals.