Smelly plant: What are they feeding you?

While flowers are typically associated with pleasant fragrances, every few years a certain part of the rainforests of Sumatra is filled with the pungent odor of rotting flesh. This smell emanates from the inflorescence of the titan arum, or corpse plant, which heats up during flowering in a process known as thermogenesis. Thermogenesis is rare in plants, but is thought to help produce the unpleasant scent that attracts the plant’s necro- or saprophagous pollinators (those that eat dead or decaying tissues). Zulfiqar and colleagues made use of different blooming events of a single titan arum specimen and its clonal plantlet to gain more insights into this rare phenomenon. RNA sequencing of different tissues of the spadix at peak thermogenesis was performed to understand the molecular basis of thermogenesis and volatile organic compound (VOC) production. Expression of genes related to sugar transport and starch breakdown showed significant but tissue-specific changes. This supports the idea that thermogenesis is linked to the mobilization of starch reserves from the tuber towards the appendix, which contains the flowers, where it is broken down. There it can then serve as the respiratory substrate for alternative oxidases, which are essential for thermogenesis. Additionally, genes involved in sulfur metabolism were elevated in the appendix as well, confirming their role in VOC production. Interestingly, the authors also detected, for the first time, elevated levels of putrescine in the spathe margin, which surrounds the appendix and has a supporting function. In conclusion, the authors provide new insights into the genetic and metabolic basis of thermogenesis in this unique plant. (Summary by Thomas Depaepe, Bluesky: @thdpaepe.bsky.social and X: @thdpaepe) PNAS Nexus 10.1093/pnasnexus/pgae492